Prescription Drugs

CLINICAL PHARMACOLOGY Mechanism of Action In cell cultures the inhibitory activity of ribavirin for respiratory syncytial virus (RSV) is selective. The mechanism of action is unknown. Reversal of the in vitroantiviral activity by guanosine or xanthosine suggests ribavirin may act as an analogue of these cellular metabolites. Microbiology Rfvavirin has demonstrated antiviral activity against RSV in vitro and in experimentally infected cotton rats.2 Several clinical isolates of RSV were evaluated for ribavirin susceptibility by plaque reduction in tissue culture. Plaques were reduced 85-98% by 16 µg/mL; however, results may vary with the test system. The development of resistance has not been evaluated in vitro or in clinical trials. In addition to the above, ribavirin has been shown to have in vitro activity against influenza A and B viruses and herpes simplex virus, but the clinical significance of these data is unknown. Immunologic Effects Neutralizing antibody responses to RSV were decreased in aerosolized VIRAZOLE (ribavirin) treated infants compared to placebo treated infants.3 One study also showed that RSV-specific IgE antibody in bronchial secretions was decreased in patients treated with aerosolized VIRAZOLE. In rats, ribavirin administration resulted in lymphoid atrophy of the thymus, spleen and lymph nodes. Humoral immunity was reduced in guinea pigs and ferrets. Cellular immunity was also mildly depressed in animal studies. The clinical significance of these observations is unknown. Pharmacokinetics Assay for VIRAZOLE (ribavirin) in human materials is by a radio immunoassay which detects ribavirin and at least one metabolite. VIRAZOLE brand of ribavirin, when administered by aerosol, is absorbed systemically. Four pediatric patients inhaling VIRAZOLE (ribavirin) aerosol administered by face mask for 2.5 hours each day for 3 days had plasma concentrations ranging from 0.44 to 1.55 fJM, with a mean concentration of 0.76 µM. The plasma half-life was reported to be 9.5 hours. Three pediatric patients inhaling aerosolized VIRAZOLE (ribavirin) administered by face mask or mist tent for 20 hours each day for 5 days had plasma concentrations ranging from 1.5 to 14.3 µM, with a mean concentration of 6.8 µM. The bioavailability of aerosolized VIRAZOLE (ribavirin) is unknown and may depend on the mode of aerosol delivery. After aerosol treatment, peak plasma concentrations of ribavirin are 85% to 98% less than the concentration that reduced RSV plaque formation in tissue culture. After aerosol treatment, respiratory tract secretions are likely to contain ribavirin in concentrations many fold higher than those required to reduce plaque formation. However, RSV is an intracellular virus and it is unknown whether plasma concentrations or respiratory secretion concentrations of the drug better reflect intracellular concentrations in the respiratory tract. In man, rats, and rhesus monkeys, accumulation of ribavirin and/or metabolites in the red blood cells has been noted, plateauing in red cells in man in about 4 days and gradually declining with an apparent half-life of 40 days (the half-life of erythrocytes). The extent of accumulation of ribavirin following inhalation therapy is not well defined. Animal Toxicology Ribavirin, when administered orally or as an aerosol, produced cardiac lesions in mice, rats, and monkeys, when given at doses of 30,36 and f 20 mg/kg or greater for 4 weeks or more (estimated human equivalent doses of 4.8,12.3 and 111.4 mg/kg for a 5 kg child, or 2.5,5.1 and 40 mg/kg for a 60 kg adult, based on body surface area adjustment). Aerosolized ribavirin administered to developing ferrets at 60 mg/kg for 10 or 30 days resulted in inflammatory and possibly emphysematous changes in the lungs. Proliferative changes were seen in the lungs following exposure at 131 mg/kg for 30 days. The significance of these findings to human administration is unknown. Description of Studies Non-Mechanlcally-Ventllated Infants: In two placebo controlled trials in infants hospitalized with RSV lower respiratory tract infection, aerosolized VIRAZOLE (ribavirin) treatment had a therapeutic effect, as judged by the reduction in severity of clinical manifestations of disease by treatment day 3.3, < Treatment was most effective when instituted within the first 3 days of clinical illness. Virus titers in respiratory secretions were also significantly reduced with VIRAZOLE (ribavirin) in one of these original studies.4 Additional controlled studies conducted since these initial trials of aerosolized VIRAZOLE (ribavirin) in the treatment of RSV infection have supported these data. Mechanically-Ventilated Infants: A randomized, double-blind, placebo controlled evaluation of aerosolized VIRAZOLE (ribavirin) at the recommended dose was conducted in 28 infants requiring mechanical ventilation for respiratory failure caused by documented RSV infection.8 Mean age was 1.4 months (SD, 1.7 months). Seven patients had underlying diseases predisposing them to severe infection and 21 were previously normal. Aerosolized VIRAZOLE (ribavirin) treatment significantly decreased the duration of mechanical ventilation required (4.9 vs. 9.9 days, p=0.01) and duration of required supplemental oxygen (8.7 vs. 13.5 days, p=0.01). Intensive patient management and monitoring techniques were employed in this study. These included endotracheal tube suctioning every 1 to 2 hours; recording of proximal airway pressure, ventilatory rate, and F102 every hour; and arterial blood gas monitoring every 2 to 6 hours. To reduce the risk of VIRAZOLE (ribavirin) precipitation and ventilator malfunction, heated wire tubing, two bacterial filters connected in series in the expiratory limb of the ventilator (with filter changes every 4 hours), and water column pressure release valves to monitor internal ventilator pressures were used in connecting ventilator circuits to the SPAG-2. Employing these techniques, no technical difficulties with VIRAZOLE (ribavirin) administration were encountered during the study. Adverse events consisted of bacterial pneumonia in one case, staphyloma bacteremia in one case and two cases of post-extubation stridor. None were felt to be related to VIRAZOLE (ribavirin) administration. REFERENCES 1. Hruska JF, Bernstein JM, Douglas Jr., RG, and Hall CB. Effects of Virazole (ribavirin) on respiratory syncytial virus in vitro. Antimicrob Agents Chemother 17:770-775,1 1980. 2. Hruska JF, Morrow PE, Suffin SC, and Douglas Jr., RG. In vivo inhibition of respiratory syncytial virus by Virazole (ribavirin) . Antimicrob Agents Chemother 21:125-130,1982. 3. Taber LH, Knight V, Gilbert BE, McClung HW et al. Virazole (ribavirin) aerosol treatment of bronchiolitis associated with respiratory tract infection in infants. Pediatrics 72:613-618,1983.

CLINICAL PHARMACOLOGY Mechanism Of Action Ribavirin is an antiviral agent [see Microbiology]. Pharmacokinetics Single- and multiple-dose pharmacokinetic properties in adults are summarized in Table 11. Ribavirin was rapidly and extensively absorbed following oral administration. However, due to first-pass metabolism, the absolute bioavailability averaged 64% (44%). There was a linear relationship between dose and AUCtf (AUC from time zero to last measurable concentration) following single doses of 200 to 1200 mg ribavirin. The relationship between dose and Cmax was curvilinear, tending to asymptote above single doses of 400 to 600 mg. Upon multiple oral dosing, based on AUC12hr, a 6-fold accumulation of ribavirin was observed in plasma. Following oral dosing with 600 mg twice daily, steady-state was reached by approximately 4 weeks, with mean steady-state plasma concentrations of 2200 ng/mL (37%). Upon discontinuation of dosing, the mean half-life was 298 (30%) hours, which probably reflects slow elimination from nonplasma compartments. Effect of Antacid on Absorption of Ribavirin Coadministration of REBETOL capsules with an antacid containing magnesium, aluminum, and simethicone resulted in a 14% decrease in mean ribavirin AUCtf. The clinical relevance of results from this single-dose study is unknown. Table 11: Mean (% CV) Pharmacokinetic Parameters for REBETOL When Administered Individually to Adults Parameter REBETOL Single-Dose 600 mg Oral Solution (N=14) Single-Dose 600 mg Capsules (N=12) Multiple-Dose 600 mg Capsules twice daily (N=12) Tmax (hr) 1.00 (34) 1.7 (46)* 3 (60) Cmax (ng/mL) 872 (42) 782 (37) 3680 (85) AUCtf (ng•hr/mL) 14,098 (38) 13,400 (48) 228,000 (25) T½ (hr) 43.6 (47) 298 (30) Apparent Volume of Distribution (L) 2825 (9)1 Apparent Clearance (L/hr) 38.2 (40) Absolute Bioavailability 64% (44)* * N=11. † Data obtained from a single-dose pharmacokinetic study using 14C labeled ribavirin; N=5. † N=6. Tissue Distribution Ribavirin transport into nonplasma compartments has been most extensively studied in red blood cells, and has been identified to be primarily via an es-type equilibrative nucleoside transporter. This type of transporter is present on virtually all cell types and may account for the extensive volume of distribution. Ribavirin does not bind to plasma proteins. Metabolism and Excretion Ribavirin has two pathways of metabolism: (i) a reversible phosphorylation pathway in nucleated cells; and (ii) a degradative pathway involving deribosylation and amide hydrolysis to yield a triazole carboxylic acid metabolite. Ribavirin and its triazole carboxamide and triazole carboxylic acid metabolites are excreted renally. After oral administration of 600 mg of 14C-ribavirin, approximately 61% and 12% of the radioactivity was eliminated in the urine and feces, respectively, in 336 hours. Unchanged ribavirin accounted for 17% of the administered dose. Special Populations Renal Dysfunction The pharmacokinetics of ribavirin were assessed after administration of a single oral dose (400 mg) of ribavirin to non HCV-infected subjects with varying degrees of renal dysfunction. The mean AUCtf value was threefold greater in subjects with creatinine clearance values between 10 to 30 mL/min when compared to control subjects (creatinine clearance greater than 90 mL/min). In subjects with creatinine clearance values between 30 to 60 mL/min, AUCtf was twofold greater when compared to control subjects. The increased AUCtf appears to be due to reduction of renal and nonrenal clearance in these subjects. Phase 3 efficacy trials included subjects with creatinine clearance values greater than 50 mL/min. The multiple-dose pharmacokinetics of ribavirin cannot be accurately predicted in patients with renal dysfunction. Ribavirin is not effectively removed by hemodialysis. Patients with creatinine clearance less than 50 mL/min should not be treated with REBETOL [see CONTRAINDICATIONS]. Hepatic Dysfunction The effect of hepatic dysfunction was assessed after a single oral dose of ribavirin (600 mg). The mean AUCtf values were not significantly different in subjects with mild, moderate, or severe hepatic dysfunction (Child-Pugh Classification A, B, or C) when compared to control subjects. However, the mean Cmax values increased with severity of hepatic dysfunction and was twofold greater in subjects with severe hepatic dysfunction when compared to control subjects. Elderly Patients Pharmacokinetic evaluations in elderly subjects have not been performed. Gender There were no clinically significant pharmacokinetic differences noted in a single-dose trial of 18 male and 18 female subjects. Pediatric Patients Multiple-dose pharmacokinetic properties for REBETOL capsules and INTRON A in pediatric subjects with chronic hepatitis C between 5 and 16 years of age are summarized in Table 12. The pharmacokinetics of REBETOL and INTRON A (dose-normalized) are similar in adults and pediatric subjects. Complete pharmacokinetic characteristics of REBETOL oral solution have not been determined in pediatric subjects. Ribavirin Cmin values were similar following administration of REBETOL oral solution or REBETOL capsules during 48 weeks of therapy in pediatric subjects (3 to 16 years of age). Table 12: Mean (% CV) Multiple-dose Pharmacokinetic Parameters for INTRON A and REBETOL Capsules When Administered to Pediatric Subjects with Chronic Hepatitis C Parameter REBETOL 15 mg/kg/day as 2 divided doses (N=17) INTRON A 3 MIU/m² three times weekly (N=54) Tmax (hr) 1.9 (83) 5.9 (36) Cmax (ng/mL) 3275 (25) 51 (48) AUC* 29,774 (26) 622 (48) Apparent Clearance L/hr/kg 0.27 (27) ND† * AUC12 (ng·hr/mL) for REBETOL; AUC0-24 (IU·hr/mL) for INTRON A. † ND=not done. Note: numbers in parenthesis indicate % coefficient of variation. A clinical trial in pediatric subjects with chronic hepatitis C between 3 and 17 years of age was conducted in which pharmacokinetics for PegIntron and REBETOL (capsules and oral solution) were evaluated. In pediatric subjects receiving body surface area-adjusted dosing of PegIntron at 60 mcg/m²/week, the log transformed ratio estimate of exposure during the dosing interval was predicted to be 58% [90% CI: 141%, 177%] higher than observed in adults receiving 1.5 mcg/kg/week. The pharmacokinetics of REBETOL (dose-normalized) in this trial were similar to those reported in a prior study of REBETOL in combination with INTRON A in pediatric subjects and in adults. Effect of Food on Absorption of Ribavirin Both AUCtf and Cmax increased by 70% when REBETOL capsules were administered with a high-fat meal (841 kcal, 53.8 g fat, 31.6 g protein, and 57.4 g carbohydrate) in a single-dose pharmacokinetic study [see DOSAGE AND ADMINISTRATION]. Microbiology Mechanism of Action The mechanism by which ribavirin contributes to its antiviral efficacy in the clinic is not fully understood. Ribavirin has direct antiviral activity in tissue culture against many RNA viruses. Ribavirin increases the mutation frequency in the genomes of several viruses and ribavirin triphosphate inhibits HCV polymerase in a biochemical reaction. Antiviral Activity in Cell Culture The antiviral activity of ribavirin in the HCV-replicon is not well understood and has not been defined because of the cellular toxicity of ribavirin. Direct antiviral activity has been observed in tissue culture of other RNA viruses. The anti-HCV activity of interferon was demonstrated in cell containing self-replicating HCV-RNS (HCV replicon cells) or HCV infection. Resistance HCV genotypes show wide variability in their response to pegylated recombinant human interferon/ribavirin therapy. Genetic changes associated with the variable response have not been identified. Cross-resistance There is no reported cross-resistance between pegylated/non-pegylated interferons and ribavirin. Animal Toxicology And Pharmacology Long-term studies in the mouse and rat [18 to 24 months; doses of 20 to 75 and 10 to 40 mg/kg/day, respectively (estimated human equivalent doses of 1.67 to 6.25 and 1.43 to 5.71 mg/kg/day, respectively, based on body surface area adjustment for a 60 kg adult; approximately 0.1 to 0.4 times the maximum human 24-hour dose of ribavirin)] have demonstrated a relationship between chronic ribavirin exposure and increased incidences of vascular lesions (microscopic hemorrhages) in mice. In rats, retinal degeneration occurred in controls, but the incidence was increased in ribavirintreated rats. In a study in which rat pups were dosed postnatally with ribavirin at doses of 10, 25, and 50 mg/kg/day, drug-related deaths occurred at 50 mg/kg (at rat pup plasma concentrations below human plasma concentrations at the human therapeutic dose) between study Days 13 and 48. Rat pups dosed from postnatal Days 7 through 63 demonstrated a minor, dose-related decrease in overall growth at all doses, which was subsequently manifested as slight decreases in body weight, crown-rump length, and bone length. These effects showed evidence of reversibility, and no histopathological effects on bone were observed. No ribavirin effects were observed regarding neurobehavioral or reproductive development. Clinical Studies Clinical Study 1 evaluated PegIntron monotherapy. See PegIntron labeling for information about this trial. REBETOL/PegIntron Combination Therapy Adult Subjects Study 2 A randomized trial compared treatment with two PegIntron/REBETOL regimens [PegIntron 1.5 mcg/kg subcutaneously once weekly/REBETOL 800 mg orally daily (in divided doses); PegIntron 1.5 mcg/kg subcutaneously once weekly for 4 weeks then 0.5 mcg/kg subcutaneously once weekly for 44 weeks/REBETOL 1000 or 1200 mg orally daily (in divided doses)] with INTRON A [3 MIU subcutaneously three times weekly/REBETOL 1000 or 1200 mg orally daily (in divided doses)] in 1530 adults with chronic hepatitis C. Interferon-naïve subjects were treated for 48 weeks and followed for 24 weeks post-treatment. Eligible subjects had compensated liver disease, detectable HCV-RNA, elevated ALT, and liver histopathology consistent with chronic hepatitis. Response to treatment was defined as undetectable HCV-RNA at 24 weeks post-treatment (see Table 13). The response rate to the PegIntron 1.5 mcg/kg and ribavirin 800 mg dose was higher than the response rate to INTRON A/REBETOL (see Table 13).The response rate to PegIntron 1.5→0.5 mcg/kg/REBETOL was essentially the same as the response to INTRON A/REBETOL (data not shown). Table 13: Rates of Response to Combination Treatment – Study 2 PegIntron 1.5 mcg/kg once weekly REBETOL 800 mg once daily INTRON A 3 MIU three times weekly REBETOL 1000/1200 mg once daily Overall response*† 52% (264/511) 46% (231/505) Genotype 1 41% (141/348) 33% (112/343) Genotype 2-6 75% (123/163) 73% (119/162) * Serum HCV-RNA was measured with a research-based quantitative polymerase chain reaction assay by a central laboratory. † Difference in overall treatment response (PegIntron/REBETOL vs. INTRON A/REBETOL) is 6% with 95% confidence interval of (0.18, 11.63) adjusted for viral genotype and presence of cirrhosis at baseline. Response to treatment was defined as undetectable HCV-RNA at 24 weeks post-treatment. Subjects with viral genotype 1, regardless of viral load, had a lower response rate to PegIntron (1.5 mcg/kg)/REBETOL (800 mg) compared to subjects with other viral genotypes. Subjects with both poor prognostic factors (genotype 1 and high viral load) had a response rate of 30% (78/256) compared to a response rate of 29% (71/247) with INTRON A/REBETOL combination therapy. Subjects with lower body weight tended to have higher adverse-reaction rates [see ADVERSE REACTIONS] and higher response rates than subjects with higher body weights. Differences in response rates between treatment arms did not substantially vary with body weight. Treatment response rates with PegIntron/REBETOL combination therapy were 49% in men and 56% in women. Response rates were lower in African American and Hispanic subjects and higher in Asians compared to Caucasians. Although African Americans had a higher proportion of poor prognostic factors compared to Caucasians, the number of non-Caucasians studied (11% of the total) was insufficient to allow meaningful conclusions about differences in response rates after adjusting for prognostic factors in this trial. Liver biopsies were obtained before and after treatment in 68% of subjects. Compared to baseline, approximately two-thirds of subjects in all treatment groups were observed to have a modest reduction in inflammation. Study 3 In a large United States community-based trial, 4913 subjects with chronic hepatitis C were randomized to receive PegIntron 1.5 mcg/kg subcutaneously once weekly in combination with a REBETOL dose of 800 to 1400 mg (weight-based dosing [WBD]) or 800 mg (flat) orally daily (in divided doses) for 24 or 48 weeks based on genotype. Response to treatment was defined as undetectable HCV-RNA (based on an assay with a lower limit of detection of 125 IU/mL) at 24 weeks post-treatment. Treatment with PegIntron 1.5 mcg/kg and REBETOL 800 to 1400 mg resulted in a higher sustained virologic response compared to PegIntron in combination with a flat 800 mg daily dose of REBETOL. Subjects weighing greater than 105 kg obtained the greatest benefit with WBD, although a modest benefit was also observed in subjects weighing greater than 85 to 105 kg (see Table 14). The benefit of WBD in subjects weighing greater than 85 kg was observed with HCV genotypes 1-3. Insufficient data were available to reach conclusions regarding other genotypes. Use of WBD resulted in an increased incidence of anemia [see ADVERSE REACTIONS]. Table 14: SVR Rate by Treatment and Baseline Weight - Study 3 Treatment Group Subject Baseline Weight < 65 kg ( < 143 lb) 65-85 kg (143-188 lb) > 85-105 kg ( > 188-231 lb) > 105 kg ( > 231 lb) WBD* 50% (173/348) 45% (449/994) 42% (351/835) 47% (138/292) Flat 51% (173/342) 44% (443/1011) 39% (318/819) 33% (91/272) * P=0.01, primary efficacy comparison (based on data from subjects weighing 65 kg or higher at baseline and utilizing a logistic regression analysis that includes treatment [WBD or Flat], genotype and presence/absence of advanced fibrosis, in the model). A total of 1552 subjects weighing greater than 65 kg in Study 3 had genotype 2 or 3 and were randomized to 24 or 48 weeks of therapy. No additional benefit was observed with the longer treatment duration. Study 4 A large randomized trial compared the safety and efficacy of treatment for 48 weeks with two PegIntron/REBETOL regimens [PegIntron 1.5 mcg/kg and 1 mcg/kg subcutaneously once weekly both in combination with REBETOL 800 to 1400 mg PO daily (in two divided doses)] and Pegasys 180 mcg subcutaneously once weekly in combination with Copegus 1000 to 1200 mg PO daily (in two divided doses) in 3070 treatment-naïve adults with chronic hepatitis C genotype 1. In this trial, lack of early virologic response (undetectable HCV-RNA or greater than or equal to 2 log10 reduction from baseline) by treatment Week 12 was the criterion for discontinuation of treatment. SVR was defined as undetectable HCV-RNA (Roche COBAS TaqMan assay, a lower limit of quantitation of 27 IU/mL) at 24 weeks post-treatment (see Table 15). Table 15: SVR Rate by Treatment – Study 4 % (number) of Subjects PegIntron 1.5 mcg/kg/REBETOL PegIntron 1 mcg/kg/REBETOL Pegasys 180 mcg/Copegus 40 (406/1019) 38 (386/1016) 41 (423/1035) Overall SVR rates were similar among the three treatment groups. Regardless of treatment group, SVR rates were lower in subjects with poor prognostic factors. Subjects with poor prognostic factors randomized to PegIntron (1.5 mcg/kg)/REBETOL or Pegasys/Copegus, however, achieved higher SVR rates compared to similar subjects randomized to PegIntron 1 mcg/kg/REBETOL. For the PegIntron 1.5 mcg/kg and REBETOL dose, SVR rates for subjects with and without the following prognostic factors were as follows: cirrhosis (10% vs. 42%), normal ALT levels (32% vs. 42%), baseline viral load greater than 600,000 IU/mL (35% vs. 61%), 40 years of age and older (38% vs. 50%), and African American race (23% vs. 44%). In subjects with undetectable HCV-RNA at treatment Week 12 who received PegIntron (1.5 mcg/kg)/REBETOL, the SVR rate was 81% (328/407). Study 5 - REBETOL/PegIntron Combination Therapy in Prior Treatment Failures In a noncomparative trial, 2293 subjects with moderate to severe fibrosis who failed previous treatment with combination alpha interferon/ribavirin were re-treated with PegIntron, 1.5 mcg/kg subcutaneously, once weekly, in combination with weight adjusted ribavirin. Eligible subjects included prior nonresponders (subjects who were HCV-RNA positive at the end of a minimum 12 weeks of treatment) and prior relapsers (subjects who were HCVRNA negative at the end of a minimum 12 weeks of treatment and subsequently relapsed after post-treatment follow-up). Subjects who were negative at Week 12 were treated for 48 weeks and followed for 24 weeks post-treatment. Response to treatment was defined as undetectable HCV-RNA at 24 weeks post-treatment (measured using a research-based test, limit of detection 125 IU/mL). The overall response rate was 22% (497/2293) (99% CI: 19.5, 23.9). Subjects with the following characteristics were less likely to benefit from re-treatment: previous nonresponse, previous pegylated interferon treatment, significant bridging fibrosis or cirrhosis, and genotype 1 infection. The re-treatment sustained virologic response rates by baseline characteristics are summarized in Table 16. Table 16: SVR Rates by Baseline Characteristics of Prior Treatment Failures - Study 5 HCV Genotype/ Metavir Fibrosis Score Overall SVR by Previous Response and Treatment Nonresponder Relapser interferon alfa/ribavirin % (number of subjects) peginterferon (2a and 2b combined)/ribavirin % (number of subjects) interferon alfa/ribavirin % (number of subjects) peginterferon (2a and 2b combined)/ribavirin % (number of subjects) Overall 18 (158/903) 6 (30/476) 43 (130/300) 35 (113/344) HCV 1 13 (98/761) 4 (19/431) 32 (67/208) 23 (56/243) F2 18 (36/202) 6 (7/117) 42 (33/79) 32 (23/72) F3 16 (38/233) 4 (4/112) 28 (16/58) 21 (14/67) F4 7 (24/325) 4 (8/202) 26 (18/70) 18 (19/104) HCV 2/3 49 (53/109) 36 (10/28) 67 (54/81) 57 (52/92) F2 68 (23/34) 56 (5/9) 76 (19/25) 61 (11/18) F3 39 (11/28) 38 (3/8) 67 (18/27) 62 (18/29) F4 40 (19/47) 18 (2/11) 59 (17/29) 51 (23/45) HCV 4 17 (5/29) 7 (1/15) 88 (7/8) 50 (4/8) Achievement of an undetectable HCV-RNA at treatment Week 12 was a strong predictor of SVR. In this trial, 1470 (64%) subjects did not achieve an undetectable HCV-RNA at treatment Week 12, and were offered enrollment into long-term treatment trials, due to an inadequate treatment response. Of the 823 (36%) subjects who were HCV-RNA undetectable at treatment Week 12, those infected with genotype 1 had an SVR of 48% (245/507), with a range of responses by fibrosis scores (F4-F2) of 39-55%. Subjects infected with genotype 2/3 who were HCV-RNA undetectable at treatment Week 12 had an overall SVR of 70% (196/281), with a range of responses by fibrosis scores (F4-F2) of 60-83%. For all genotypes, higher fibrosis scores were associated with a decreased likelihood of achieving SVR. Pediatric Subjects Previously untreated pediatric subjects 3 to 17 years of age with compensated chronic hepatitis C and detectable HCV-RNA were treated with REBETOL 15 mg/kg per day and PegIntron 60 mcg/m² once weekly for 24 or 48 weeks based on HCV genotype and baseline viral load. All subjects were to be followed for 24 weeks post-treatment. A total of 107 subjects received treatment, of which 52% were female, 89% were Caucasian, and 67% were infected with HCV Genotype 1. Subjects infected with Genotypes 1, 4 or Genotype 3 with HCV-RNA greater than or equal to 600,000 IU/mL received 48 weeks of therapy while those infected with Genotype 2 or Genotype 3 with HCV-RNA less than 600,000 IU/mL received 24 weeks of therapy. The trial results are summarized in Table 17. Table 17: Sustained Virologic Response Rates by Genotype and Assigned Treatment Duration – Pediatric Trial Genotype All Subjects N=107 24 Weeks 48 Weeks Virologic Response N*† (%) Virologic Response N*† (%) All 26/27 (96.3) 44/80 (55.0) 1 - 38/72 (52.8) 2 14/15 (93.3) - 3‡ 12/12 (100) 2/3 (66.7) 4 - 4/5 (80.0) * Response to treatment was defined as undetectable HCV-RNA at 24 weeks post-treatment. † N=number of responders/number of subjects with given genotype, and assigned treatment duration. ‡ Subjects with genotype 3 low viral load (less than 600,000 IU/mL) were to receive 24 weeks of treatment while those with genotype 3 and high viral load were to receive 48 weeks of treatment REBETOL/INTRON A Combination Therapy Adult Subjects Previously Untreated Subjects Adults with compensated chronic hepatitis C and detectable HCV-RNA (assessed by a central laboratory using a research-based RT-PCR assay) who were previously untreated with alpha interferon therapy were enrolled into two multicenter, double-blind trials (US and international) and randomized to receive REBETOL capsules 1200 mg/day (1000 mg/day for subjects weighing less than or equal to 75 kg) and INTRON A 3 MIU three times weekly or INTRON A and placebo for 24 or 48 weeks followed by 24 weeks of off-therapy follow-up. The international trial did not contain a 24-week INTRON A and placebo treatment arm. The US trial enrolled 912 subjects who, at baseline, were 67% male, 89% Caucasian with a mean Knodell HAI score (I+II+III) of 7.5, and 72% genotype 1. The international trial, conducted in Europe, Israel, Canada, and Australia, enrolled 799 subjects (65% male, 95% Caucasian, mean Knodell score 6.8, and 58% genotype 1). Trial results are summarized in Table 18. Table 18: Virologic and Histologic Responses: Previously Untreated Subjects* US Trial International Trial 24 weeks of treatment 48 weeks of treatment 24 weeks of treatment 48 weeks of treatment INTRON A/ REBETOL (N=228) INTRON A/ Placebo (N=231) INTRON A/ REBETOL (N=228) INTRON A/ Placebo (N=225) INTRON A/ REBETOL (N=265) INTRON A/ REBETOL (N=268) INTRON A/ Placebo (N=266) Virologic Response Responder† 65 (29) 13 (6) 85 (37) 27 (12) 86 (32) 113 (42) 46 (17) Nonresponder 147 (64) 194 (84) 110 (48) 168 (75) 158 (60) 120 (45) 196 (74) Missing Data 16 (7) 24 (10) 33 (14) 30 (13) 21 (8) 35 (13) 24 (9) Histologic Response Improvement‡ 102 (45) 77 (33) 96 (42) 65 (29) 103 (39) 102 (38) 69 (26) No improvement 77 (34) 99 (43) 61 (27) 93 (41) 85 (32) 58 (22) 111 (41) Missing Data 49 (21) 55 (24) 71 (31) 67 (30) 77 (29) 108 (40) 86 (32) * Number (%) of subjects. † Defined as HCV-RNA below limit of detection using a research-based RT-PCR assay at end of treatment and during follow-up period. ‡ Defined as post-treatment (end of follow-up) minus pretreatment liver biopsy Knodell HAI score (I+II+III) improvement of greater than or equal to 2 points. Of subjects who had not achieved HCV-RNA below the limit of detection of the research-based assay by Week 24 of REBETOL/INTRON A treatment, less than 5% responded to an additional 24 weeks of combination treatment. Among subjects with HCV Genotype 1 treated with REBETOL/INTRON A therapy who achieved HCV-RNA below the detection limit of the research-based assay by 24 weeks, those randomized to 48 weeks of treatment had higher virologic responses compared to those in the 24-week treatment group. There was no observed increase in response rates for subjects with HCV non-genotype 1 randomized to REBETOL/INTRON A therapy for 48 weeks compared to 24 weeks. Relapse Subjects Subjects with compensated chronic hepatitis C and detectable HCV-RNA (assessed by a central laboratory using a research-based RT-PCR assay) who had relapsed following one or two courses of interferon therapy (defined as abnormal serum ALT levels) were enrolled into two multicenter, double-blind trials (US and international) and randomized to receive REBETOL 1200 mg/day (1000 mg/day for subjects weighing ≤ 75 kg) and INTRON A 3 MIU three times weekly or INTRON A and placebo for 24 weeks followed by 24 weeks of off-therapy follow-up. The US trial enrolled 153 subjects who, at baseline, were 67% male, 92% Caucasian with a mean Knodell HAI score (I+II+III) of 6.8, and 58% genotype 1. The international trial, conducted in Europe, Israel, Canada, and Australia, enrolled 192 subjects (64% male, 95% Caucasian, mean Knodell score 6.6, and 56% genotype 1).  Trial results are summarized in Table 19. Table 19: Virologic and Histologic Responses: Relapse Subjects* US Trial International Trial INTRON A/ REBETOL (N=77) INTRON A/ Placebo (N=76) INTRON A/ REBETOL (N=96) INTRON A/ Placebo (N=96) Virologic Response Responder† 33 (43) 3 (4) 46 (48) 5 (5) Nonresponder 36 (47) 66 (87) 45 (47) 91 (95) Missing Data 8 (10) 7 (9) 5 (5) 0 (0) Histologic Response Improvement‡ 38 (49) 27 (36) 49 (51) 30 (31) No improvement 23 (30) 37 (49) 29 (30) 44 (46) Missing Data 16 (21) 12 (16) 18 (19) 22 (23) * Number (%) of subjects. † Defined as HCV-RNA below limit of detection using a research-based RT-PCR assay at end of treatment and during follow-up period. ‡ Defined as post-treatment (end of follow-up) minus pretreatment liver biopsy Knodell HAI score (I+II+III) improvement of greater than or equal to 2 points. Virologic and histologic responses were similar among male and female subjects in both the previously untreated and relapse trials. Pediatric Subjects Pediatric subjects 3 to 16 years of age with compensated chronic hepatitis C and detectable HCV-RNA (assessed by a central laboratory using a research-based RT-PCR assay) were treated with REBETOL 15 mg/kg per day and INTRON A 3 MIU/m² three times weekly for 48 weeks followed by 24 weeks of off-therapy follow-up. A total of 118 subjects received treatment, of which 57% were male, 80% Caucasian, and 78% genotype 1. Subjects less than 5 years of age received REBETOL oral solution and those 5 years of age or older received either REBETOL oral solution or capsules. Trial results are summarized in Table 20. Table 20: Virologic Response: Previously Untreated Pediatric Subjects* INTRON A 3 MIU/m² three times weekly/ REBETOL 15 mg/kg/day Overall Response† (N=118) 54 (46) Genotype 1 (N=92) 33 (36) Genotype non-1 (N=26) 21 (81) * Number (%) of subjects. † Defined as HCV-RNA below limit of detection using a research-based RTPCR assay at end of treatment and during follow-up period. Subjects with viral genotype 1, regardless of viral load, had a lower response rate to INTRON A/REBETOL combination therapy compared to subjects with genotype non-1, 36% vs. 81%. Subjects with both poor prognostic factors (genotype 1 and high viral load) had a response rate of 26% (13/50).

CLINICAL PHARMACOLOGY Mechanism Of Action Ribavirin is an antiviral drug [see Microbiology]. Pharmacokinetics Multiple dose ribavirin pharmacokinetic data are available for HCV patients who received ribavirin in combination with peginterferon alfa-2a. Following administration of 1200 mg/day with food for 12 weeks mean±SD (n=39; body weight greater than 75 kg) AUC0-12hr was 25,361±7110 ng·hr/mL and Cmax was 2748±818 ng/mL. The average time to reach Cmax was 2 hours. Trough ribavirin plasma concentrations following 12 weeks of dosing with food were 1662±545 ng/mL in HCV infected patients who received 800 mg/day (n=89), and 2112±810 ng/mL in patients who received 1200 mg/day (n=75; body weight greater than 75 kg). The terminal half-life of ribavirin following administration of a single oral dose of COPEGUS is about 120 to 170 hours. The total apparent clearance following administration of a single oral dose of COPEGUS is about 26 L/h. There is extensive accumulation of ribavirin after multiple dosing (twice daily) such that the Cmax at steady state was four-fold higher than that of a single dose. Effect of Food on Absorption of Ribavirin Bioavailability of a single oral dose of ribavirin was increased by co-administration with a high-fat meal. The absorption was slowed (Tmax was doubled) and the AUC0-192h and Cmax increased by 42% and 66%, respectively, when COPEGUS was taken with a high-fat meal compared with fasting conditions [see DOSAGE AND ADMINISTRATION and PATIENT INFORMATION]. Elimination and Metabolism The contribution of renal and hepatic pathways to ribavirin elimination after administration of COPEGUS is not known. In vitro studies indicate that ribavirin is not a substrate of CYP450 enzymes. Renal Impairment A clinical trial evaluated 50 CHC subjects with either moderate (creatinine clearance 30 to 50 mL/min) or severe (creatinine clearance less than 30 mL/min) renal impairment or end stage renal disease (ESRD) requiring chronic hemodialysis (HD). The apparent clearance of ribavirin was reduced in subjects with creatinine clearance less than or equal to 50 mL/min, including subjects with ESRD on HD, exhibiting approximately 30% of the value found in subjects with normal renal function. Pharmacokinetic modeling and simulation indicates that a dose of 200 mg daily in patients with severe renal impairment and a dose of 200 mg daily alternating with 400 mg the following day in patients with moderate renal impairment will provide plasma ribavirin exposures similar to that observed in patients with normal renal function receiving the standard 1000/1200 mg COPEGUS daily dose. These doses have not been studied in patients. In 18 subjects with ESRD receiving chronic HD, COPEGUS was administered at a dose of 200 mg daily. Ribavirin plasma exposures in these subjects were approximately 20% lower compared to subjects with normal renal function receiving the standard 1000/1200 mg COPEGUS daily dose [see DOSAGE AND ADMINISTRATION, Use In Specific Populations]. Plasma ribavirin is removed by hemodialysis with an extraction ratio of approximately 50%; however, due to the large volume of distribution of ribavirin, plasma exposure is not expected to change with hemodialysis. Microbiology Mechanism of Action The mechanism by which ribavirin contributes to its antiviral efficacy in the clinic is not fully understood. Ribavirin has direct antiviral activity in tissue culture against many RNA viruses. Ribavirin increases the mutation frequency in the genomes of several RNA viruses and ribavirin triphosphate inhibits HCV polymerase in a biochemical reaction. Antiviral Activity in Cell Culture In the stable HCV cell culture model system (HCV replicon), ribavirin inhibited autonomous HCV RNA replication with a 50% effective concentration (EC50) value of 11-21 mcM. In the same model, PEG-IFN α-2a also inhibited HCV RNA replication, with an EC50 value of 0.1-3 ng/mL. The combination of PEG-IFN α-2a and ribavirin was more effective at inhibiting HCV RNA replication than either agent alone. Resistance Different HCV genotypes display considerable clinical variability in their response to PEG-IFN-α and ribavirin therapy. Viral genetic determinants associated with the variable response have not been definitively identified. Cross-resistance Cross-resistance between IFN α and ribavirin has not been observed. Animal Toxicology In a study in rats, it was concluded that dominant lethality was not induced by ribavirin at doses up to 200 mg/kg for 5 days (up to 1.7 times the maximum recommended human dose of ribavirin). Long-term studies in the mouse and rat (18 to 24 months; dose 20 to 75, and 10 to 40 mg/kg/day, respectively, approximately 0.1 to 0.4 times the maximum daily human dose of ribavirin) have demonstrated a relationship between chronic ribavirin exposure and an increased incidence of vascular lesions (microscopic hemorrhages) in mice. In rats, retinal degeneration occurred in controls, but the incidence was increased in ribavirin-treated rats. Clinical Studies Chronic Hepatitis C Patients Adult Patients The safety and effectiveness of PEGASYS in combination with COPEGUS for the treatment of hepatitis C virus infection were assessed in two randomized controlled clinical trials. All patients were adults, had compensated liver disease, detectable hepatitis C virus, liver biopsy diagnosis of chronic hepatitis, and were previously untreated with interferon. Approximately 20% of patients in both studies had compensated cirrhosis (Child-Pugh class A). Patients coinfected with HIV were excluded from these studies. In Study NV15801, patients were randomized to receive either PEGASYS 180 mcg subcutaneous once weekly with an oral placebo, PEGASYS 180 mcg once weekly with COPEGUS 1000 mg by mouth (body weight less than 75 kg) or 1200 mg by mouth (body weight greater than or equal to 75 kg) or interferon alfa-2b 3 MIU subcutaneous three times a week plus ribavirin 1000 mg or 1200 mg by mouth. All patients received 48 weeks of therapy followed by 24 weeks of treatment-free follow-up. COPEGUS or placebo treatment assignment was blinded. Sustained virological response was defined as undetectable (less than 50 IU/mL) HCV RNA on or after study week 68. PEGASYS in combination with COPEGUS resulted in a higher SVR compared to PEGASYS alone or interferon alfa-2b and ribavirin (Table 9). In all treatment arms, patients with viral genotype 1, regardless of viral load, had a lower response rate to PEGASYS in combination with COPEGUS compared to patients with other viral genotypes. Table 9 : Sustained Virologic Response (SVR) to Combination Therapy (Study NV15801) Interferon alfa-2b + Ribavirin 1000 mg or 1200 mg PEGASYS + placebo PEGASYS + COPEGUS 1000 mg or 1200 mg All patients 197/444 (44%) 65/224 (29%) 241/453 (53%) Genotype 1 103/285 (36%) 29/145 (20%) 132/298 (44%) Genotypes 2-6 94/159 (59%) 36/79 (46%) 109/155 (70%) Difference in overall treatment response (PEGASYS/COPEGUS – Interferon alfa-2b/ribavirin) was 9% (95% CI 2.3, 15.3). In Study NV15942, all patients received PEGASYS 180 mcg subcutaneous once weekly and were randomized to treatment for either 24 or 48 weeks and to a COPEGUS dose of either 800 mg or 1000 mg/1200 mg (for body weight less than 75 kg/greater than or equal to 75 kg). Assignment to the four treatment arms was stratified by viral genotype and baseline HCV viral titer. Patients with genotype 1 and high viral titer (defined as greater than 2 x 106 HCV RNA copies/mL serum) were preferentially assigned to treatment for 48 weeks. Sustained Virologic Response (SVR) and HCV Genotype HCV 1 and 4 — Irrespective of baseline viral titer, treatment for 48 weeks with PEGASYS and 1000 mg or 1200 mg of COPEGUS resulted in higher SVR (defined as undetectable HCV RNA at the end of the 24-week treatment-free follow-up period) compared to shorter treatment (24 weeks) and/or 800 mg COPEGUS. HCV 2 and 3 — Irrespective of baseline viral titer, treatment for 24 weeks with PEGASYS and 800 mg of COPEGUS resulted in a similar SVR compared to longer treatment (48 weeks) and/or 1000 mg or 1200 mg of COPEGUS (see Table 10). The numbers of patients with genotype 5 and 6 were too few to allow for meaningful assessment. Table 10 : Sustained Virologic Response as a Function of Genotype (Study NV15942) 24 Weeks Treatment 48 Weeks Treatment PEGASYS + COPEGUS 800 mg (N=207) PEGASYS + COPEGUS 1000 mg or 1200 mg* (N=280) PEGASYS + COPEGUS 800 mg (N=361) PEGASYS + COPEGUS 1000 mg or 1200 mg* (N=436) Genotype 1 29/101 (29%) 48/118 (41%) 99/250 (40%) 138/271 (51%) Genotypes 2, 3 79/96 (82%) 116/144 (81%) 75/99 (76%) 117/153 (76%) Genotype 4 0/5 (0%) 7/12 (58%) 5/8 (63%) 9/11 (82%) *1000 mg for body weight less than 75 kg; 1200 mg for body weight greater than or equal to 75 kg. Pediatric Patients Previously untreated pediatric subjects 5 through 17 years of age (55% less than 12 years old) with chronic hepatitis C, compensated liver disease and detectable HCV RNA were treated with COPEGUS approximately 15 mg/kg/day plus PEGASYS 180 mcg/1.73 m² x body surface area once weekly for 48 weeks. All subjects were followed for 24 weeks post-treatment. Sustained virological response (SVR) was defined as undetectable (less than 50 IU/mL) HCV RNA on or after study week 68. A total of 114 subjects were randomized to receive either combination treatment of COPEGUS plus PEGASYS or PEGASYS monotherapy; subjects failing PEGASYS monotherapy at 24 weeks or later could receive open-label COPEGUS plus PEGASYS. The initial randomized arms were balanced for demographic factors; 55 subjects received initial combination treatment of COPEGUS plus PEGASYS and 59 received PEGASYS plus placebo; in the overall intent-to-treat population, 45% were female, 80% were Caucasian, and 81% were infected with HCV genotype 1. The SVR results are summarized in Table 11. Table 11 : Sustained Virologic Response (Study NV17424) PEGASYS 180 mcg/1.73 m² x BSA + COPEGUS 15 mg/kg* (N=55) PEGASYS 180 mcg/1.73 m² x BSA + Placebo* (N=59) All HCV genotypes** 29 (53%) 12 (20%) HCV genotype 1 21/45 (47%) 8/47 (17%) HCV non-genotype 1*** 8/10 (80%) 4/12 (33%) *Results indicate undetectable HCV RNA defined as HCV RNA less than 50 IU/mL at 24 weeks post-treatment using the AMPLICOR HCV test v2 **Scheduled treatment duration was 48 weeks regardless of the genotype ***Includes HCV genotypes 2,3 and others Other Treatment Response Predictors Treatment response rates are lower in patients with poor prognostic factors receiving pegylated interferon alpha therapy. In studies NV15801 and NV15942, treatment response rates were lower in patients older than 40 years (50% vs. 66%), in patients with cirrhosis (47% vs. 59%), in patients weighing over 85 kg (49% vs. 60%), and in patients with genotype 1 with high vs. low viral load (43% vs. 56%). African-American patients had lower response rates compared to Caucasians. In studies NV15801 and NV15942, lack of early virologic response by 12 weeks (defined as HCV RNA undetectable or greater than 2 log10 lower than baseline) was grounds for discontinuation of treatment. Of patients who lacked an early viral response by 12 weeks and completed a recommended course of therapy despite a protocol-defined option to discontinue therapy, 5/39 (13%) achieved an SVR. Of patients who lacked an early viral response by 24 weeks, 19 completed a full course of therapy and none achieved an SVR. Chronic Hepatitis C/HIV Coinfected Patients In Study NR15961, patients with CHC/HIV were randomized to receive either PEGASYS 180 mcg subcutaneous once weekly plus an oral placebo, PEGASYS 180 mcg once weekly plus COPEGUS 800 mg by mouth daily or interferon alfa-2a, 3 MIU subcutaneous three times a week plus COPEGUS 800 mg by mouth daily. All patients received 48 weeks of therapy and sustained virologic response (SVR) was assessed at 24 weeks of treatment-free follow-up. COPEGUS or placebo treatment assignment was blinded in the PEGASYS treatment arms. All patients were adults, had compensated liver disease, detectable hepatitis C virus, liver biopsy diagnosis of chronic hepatitis C, and were previously untreated with interferon. Patients also had CD4+ cell count greater than or equal to 200 cells/mm³ or CD4+ cell count greater than or equal to 100 cells/mm³ but less than 200 cells/mm³ and HIV-1 RNA less than 5000 copies/mL, and stable status of HIV. Approximately 15% of patients in the study had cirrhosis. Results are shown in Table 12. Table 12 : Sustained Virologic Response in Patients with Chronic Hepatitis C Coinfected With HIV (Study NR15961) Interferon alfa-2a + COPEGUS 800 mg (N=289) PEGASYS + Placebo (N=289) PEGASYS + COPEGUS 800 mg (N=290) All patients 33 (11%) 58 (20%) 116 (40%) Genotype 1 12/171 (7%) 24/175 (14%) 51/176 (29%) Genotypes 2, 3 18/89 (20%) 32/90 (36%) 59/95 (62%) Treatment response rates were lower in CHC/HIV patients with poor prognostic factors (including HCV genotype 1, HCV RNA greater than 800,000 IU/mL, and cirrhosis) receiving pegylated interferon alpha therapy. Of the patients who did not demonstrate either undetectable HCV RNA or at least a 2 log10 reduction from baseline in HCV RNA titer by 12 weeks of PEGASYS and COPEGUS combination therapy, 2% (2/85) achieved an SVR. In CHC patients with HIV coinfection who received 48 weeks of PEGASYS alone or in combination with COPEGUS treatment, mean and median HIV RNA titers did not increase above baseline during treatment or 24 weeks post-treatment.

Find Lowest Prices on VIRAZOLE® (ribavirin) for Inhalation Solution, USP WARNINGS USE OF AEROSOLIZED VIRAZOLE (ribavirin) IN PATIENTS REQUIRING MECHANICAL VENTILATOR ASSISTANCE SHOULD BE UNDERTAKEN ONLY BY PHYSICIANS AND SUPPORT STAFF FAMILIAR WITH THE SPECIFIC VENTILATOR BEING USED AND THIS MODE OF ADMINISTRATION OF THE DRUG. STRICT ATTENTION MUST BE PAID TO PROCEDURES THAT HAVE BEEN SHOWN TO MINIMIZE THE ACCUMULATION OF DRUG PRECIPITATE, WHICH CAN RESULT IN MECHANICAL VENTILATOR DYSFUNCTION AND ASSOCIATED INCREASED PULMONARY PRESSURES (SEE WARNINGS). SUDDEN DETERIORATION OF RESPIRATORY FUNCTION HAS BEEN ASSOCIATED WITH INITIATION OF AEROSOLIZED VIRAZOLE (ribavirin) USE IN INFANTS. RESPIRATORY FUNCTION SHOULD BE CAREFULLY MONITORED DURING TREATMENT. IF INITIATION OF AEROSOLIZED VIRAZOLE (ribavirin) TREATMENT APPEARS TO PRODUCE SUDDEN DETERIORATION OF RESPIRATORY FUNCTION, TREATMENT SHOULD BE STOPPED AND REINSTITUTED ONLY WITH EXTREME CAUTION, CONTINUOUS MONITORING AND CONSIDERATION OF CONCOMITANT ADMINISTRATION OF BRONCHODILATORS (SEE WARNINGS). VIRAZOLE (ribavirin) IS NOT INDICATED FOR USE IN ADULTS. PHYSICIANS AND PATIENTS SHOULD BE AWARE THAT RIBAVIRIN HAS BEEN SHOWN TO PRODUCE TESTICULAR LESIONS IN RODENTS AND TO BE TERATOGENIC IN ALL ANIMAL SPECIES IN WHICH ADEQUATE STUDIES HAVE BEEN CONDUCTED (RODENTS AND RABBITS); (SEE CONTRAINDICATIONS). DESCRIPTION VIRAZOLE is a brand name for ribavirin, a synthetic nucleoside with antiviral activity. VIRAZOLE (ribavirin) for inhalation solution is a sterile, lyophilized powder to be reconstituted for aerosol administration. Each 100 mL glass vial contains 6 grams of ribavirin, and when reconstituted to the recommended volume of 300 mL with sterile water for injection or sterile water for inhalation (no preservatives added), will contain 20 mg of ribavirin per mL, pH approximately 5.5. Aerosolization is to be carried out in a Small Particle Aerosol Generator (SPAG-2) nebulizer only. Ribavirin is 1-beta-D-ribofuranosyl-1H-1,2,4-triazole-3-cart)oxamide: with the following structural formula: Ribavirin is a stable, white crystalline compound with a maximum solubility in water of 142 mg/mLat25°C and with only a slight solubility in ethanol. The empirical formula is C8Hl2N405 and the molecular weight is 244.21.

Find Lowest Prices on REBETOL® (ribavirin USP) WARNING RISK OF SERIOUS DISORDERS AND RIBAVIRIN-ASSOCIATED EFFECTS REBETOL monotherapy is not effective for the treatment of chronic hepatitis C virus infection and should not be used alone for this indication [see WARNINGS AND PRECAUTIONS]. The primary toxicity of ribavirin is hemolytic anemia. The anemia associated with REBETOL therapy may result in worsening of cardiac disease that has led to fatal and nonfatal myocardial infarctions. Patients with a history of significant or unstable cardiac disease should not be treated with REBETOL [see DOSAGE AND ADMINISTRATION, WARNINGS AND PRECAUTIONS, and ADVERSE REACTIONS]. Significant teratogenic and embryocidal effects have been demonstrated in all animal species exposed to ribavirin. In addition, ribavirin has a multiple-dose half-life of 12 days, and so it may persist in nonplasma compartments for as long as 6 months. Therefore, REBETOL therapy is contraindicated in women who are pregnant and in the male partners of women who are pregnant. Extreme care must be taken to avoid pregnancy during therapy and for 6 months after completion of treatment in both female patients and in female partners of male patients who are taking REBETOL therapy. At least two reliable forms of effective contraception must be utilized during treatment and during the 6-month post-treatment follow-up period [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS, Use in Specific Populations, Nonclinical Toxicology, and PATIENT INFORMATION]. DESCRIPTION REBETOL (ribavirin), is a synthetic nucleoside analogue (purine analogue). The chemical name of ribavirin is 1-β-D-ribofuranosyl-1H-1,2,4-triazole-3-carboxamide and has the following structural formula (see Figure 1). Figure 1: Structural Formula Ribavirin is a white, crystalline powder. It is freely soluble in water and slightly soluble in anhydrous alcohol. The empirical formula is C8H12N4O5 and the molecular weight is 244.21. REBETOL capsules consist of a white powder in a white, opaque, gelatin capsule. Each capsule contains 200 mg ribavirin and the inactive ingredients microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, and magnesium stearate. The capsule shell consists of gelatin, sodium lauryl sulfate, silicon dioxide, and titanium dioxide. The capsule is printed with edible blue pharmaceutical ink which is made of shellac, anhydrous ethyl alcohol, isopropyl alcohol, n-butyl alcohol, propylene glycol, ammonium hydroxide, and FD&C Blue #2 aluminum lake. REBETOL oral solution is a clear, colorless to pale or light yellow bubble gum-flavored liquid. Each milliliter of the solution contains 40 mg of ribavirin and the inactive ingredients sucrose, glycerin, sorbitol, propylene glycol, sodium citrate, citric acid, sodium benzoate, natural and artificial flavor for bubble gum #15864, and water.

Find Lowest Prices on COPEGUS® (ribavirin) Tablets WARNING RISK OF SERIOUS DISORDERS AND RIBAVIRIN-ASSOCIATED EFFECTS COPEGUS (ribavirin) monotherapy is not effective for the treatment of chronic hepatitis C virus infection and should not be used alone for this indication. The primary clinical toxicity of ribavirin is hemolytic anemia. The anemia associated with ribavirin therapy may result in worsening of cardiac disease and lead to fatal and nonfatal myocardial infarctions. Patients with a history of significant or unstable cardiac disease should not be treated with COPEGUS [see WARNINGS AND PRECAUTIONS, ADVERSE REACTIONS, and DOSAGE AND ADMINISTRATION]. Significant teratogenic and/or embryocidal effects have been demonstrated in all animal species exposed to ribavirin. In addition, ribavirin has a multiple dose half-life of 12 days, and it may persist in non-plasma compartments for as long as 6 months. Therefore, ribavirin, including COPEGUS, is contraindicated in women who are pregnant and in the male partners of women who are pregnant. Extreme care must be taken to avoid pregnancy during therapy and for 6 months after completion of therapy in both female patients and in female partners of male patients who are taking ribavirin therapy. At least two reliable forms of effective contraception must be utilized during treatment and during the 6-month post treatment follow-up period [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS, and Use in Specific Populations]. DESCRIPTION COPEGUS, ribavirin, is a nucleoside analogue with antiviral activity. The chemical name of ribavirin is 1-β-Dribofuranosyl-1H-1,2,4-triazole-3-carboxamide and has the following structural formula: The empirical formula of ribavirin is C8H12N4O5 and the molecular weight is 244.2. Ribavirin is a white to off-white powder. It is freely soluble in water and slightly soluble in anhydrous alcohol. COPEGUS (ribavirin) is available as a light pink to pink colored, flat, oval-shaped, film-coated tablet for oral administration. Each tablet contains 200 mg of ribavirin and the following inactive ingredients: pregelatinized starch, microcrystalline cellulose, sodium starch glycolate, cornstarch, and magnesium stearate. The coating of the tablet contains Chromatone-P or Opadry Pink (made by using hydroxypropyl methyl cellulose, talc, titanium dioxide, synthetic yellow iron oxide, and synthetic red iron oxide), ethyl cellulose (ECD-30), and triacetin.

INDICATIONS VIRAZOLE (ribavirin) is indicated for the treatment of hospitalized infants and young children with severe lower respiratory tract infections due to respiratory syncytial virus. Treatment early in the course of severe lower respiratory tract infection may be necessary to achieve efficacy. Only severe RSV lower respiratory tract infection should be treated with VIRAZOLE (ribavirin) . The vast majority of infants and children with RSV infection have disease that is mild, self-limited, and does not require hospitalization or antiviral treatment. Many children with mild lower respiratory tract involvement will require shorter hospitalization than would be required for a full course of VIRAZOLE (ribavirin) aerosol (3 to 7 days) and should not be treated with the drug. Thus the decision to treat with VIRAZOLE (ribavirin) should be based on the severity of the RSV infection. The presence of an underlying condition such as prematurity, immunosuppression or cardiopulmonary disease may increase the severity of clinical manifestations and complications of RSV infection. Use of aerosolized VIRAZOLE (ribavirin) in patients requiring mechanical ventilator assistance should be undertaken only by physicians and support staff familiar with this mode of administration and the specific ventilator being used (see WARNINGS, and DOSAGE AND ADMINISTRATION). Diagnosis RSV infection should be documented by a rapid diagnostic method such as demonstration of viral antigen in respiratory tract secretions by immunofluorescence3 or ELISA5 before or during the first 24 hours of treatment. Treatment may be initiated while awaiting rapid diagnostic test results. However, treatment should not be continued without documentation of RSV infection. Non-culture antigen detection techniques may have false positive or false negative results. Assessment of the clinical situation, the time of year and other parameters may warrant reevaluation of the laboratory diagnosis. DOSAGE AND ADMINISTRATION BEFORE USE, READ THOROUGHLY THE VALEANT SMALL PARTICLE AEROSOL GENERATOR SPAG-2 OPERATOR'S MANUAL FOR SMALL PARTICLE AEROSOL GENERATOR OPERATING INSTRUCTIONS. AEROSOLIZED VIRAZOLE (ribavirin) SHOULD NOT BE ADMINISTERED WITH ANY OTHER AEROSOL GENERATING DEVICE. The recommended treatment regimen is 20 mg/mL VIRAZOLE (ribavirin) as the starting solution in the drug reservoir of the SPAG-2 unit, with continuous aerosol administration for 12-18 hours per day for 3 to 7 days. Using the recommended drug concentration of 20 mg/mL the average aerosol concentration for a 12 hour delivery period would be 190 micrograms/liter of air. Aerosolized VIRAZOLE (ribavirin) should not be administered in a mixture for combined aerosolization or simultaneously with other aerosolized medications. Non-mechanically ventilated infants VIRAZOLE (ribavirin) should be delivered to an infant oxygen hood from the SPAG-2 aerosol generator. Administration by face mask or oxygen tent may be necessary If a hood cannot be employed (see SPAG-2 manual). However, the volume and condensation area are larger in a tent and this may alter delivery dynamics of the drug. Mechanically Ventilated Infants The recommended dose and administration schedule for infants who require mechanical ventilation is the same as for those who do not. Either a pressure or volume cycle ventilator may be used in conjunction with the SPAG-2. In either case, patients should have their endotracheal tubes suctioned every 1-2 hours, and their pulmonary pressures monitored frequently (every 2-4 hours). For both pressure and volume ventilators, heated wire connective tubing and bacteria filters in series in the expiratory limb of the system (which must be changed frequently, i.e., every 4 hours) must be used to minimize the risk of VIRAZOLE (ribavirin) precipitation in the system and the subsequent risk of ventilator dysfunction. Water column pressure release valves should be used in the ventilator circuit for pressure cycled ventilators, and may be utilized with volume cycled ventilators (SEE SPAG-2 MANUAL FOR DETAILED INSTRUCTIONS). Method of Preparation VIRAZOLE brand of ribavirin is supplied as 6 grams of lyophilized powder per 100 mL vial for aerosol administration only. By sterile technique, reconstitute drug with a minimum of 75 mL of sterile USP water for Infection or Inhalation in the original 100 mL glass vial. Shake well. Transfer to the clean, sterilized 500 mL SPAG-2 reservoir and further dilute to a final volume of 300 mL with Sterile Water for Injection, USP, or Inhalation. The final concentration should be 20 mg/mL. Important: This water should NOT have had any anti microbial agent or other substance added. The solution should be inspected visually for particulate matter and discoloration prior to administration. Solutions that have been placed in the SPAG-2 unit should be discarded at least every 24 hours and when the liquid level is low before adding newly reconstituted solution. HOW SUPPLIED VIRAZOLE (Ribavirin for Inhalation Solution, USP) is supplied in four packs containing 100 mL glass vials with 6 grams of Sterile, lyophilized drug (NDC 0187-0007-14) which is to be reconstituted with 300 mL Sterile Water for Injection or Sterile Water for Inhalation (no preservatives added) and administered only by a small particle aerosol generator (SPAG-2). Vials containing the lyophilized drug powder should be stored in a dry place at 25°C (77° F); excursions permitted to 15°C-30°C (59°F-86° F). Reconstituted solutions may be stored, under sterile conditions, at room temperature (20-30°C, 68-86°F) for 24 hours. Solutions which have been placed in the SPAG-2 unit should be discarded at least every 24 hours. REFERENCES 3. Taber LH, Knight V, Gilbert BE, McClung HW et al. Virazole (ribavirin) aerosol treatment of bronchiolitis associated with respiratory tract infection in infants. Pediatrics 72:613-618,1983. 5. Hendry RM, Mcintosh K, Fahnestock ML, and Pierik LT. Enzyme-linked immunosorbent assay for detection of respiratory syncytial virus infection J Clin Microbiol 16:329-33,1982. Copies of the Report may be purchased from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161; Ask for Publication PB 93119-345 Manufactured for: Valeant Pharmaceuticals North America 3300 Hyland Ave. Costa Mesa, CA 92626 U.S.A. Rev. 05-06. FDA rev date: 2/28/2000

INDICATIONS Chronic Hepatitis C (CHC) REBETOL® (ribavirin) in combination with interferon alfa-2b (pegylated and nonpegylated) is indicated for the treatment of Chronic Hepatitis C (CHC) in patients 3 years of age and older with compensated liver disease [see WARNINGS AND PRECAUTIONS, and Use in Specific Populations]. The following points should be considered when initiating REBETOL combination therapy with PegIntron® or INTRON A® : These indications are based on achieving undetectable HCV-RNA after treatment for 24 or 48 weeks and maintaining a Sustained Virologic Response (SVR) 24 weeks after the last dose. Combination therapy with REBETOL/PegIntron is preferred over REBETOL/INTRON A as this combination provides substantially better response rates [see Clinical Studies]. Patients with the following characteristics are less likely to benefit from re-treatment after failing a course of therapy: previous nonresponse, previous pegylated interferon treatment, significant bridging fibrosis or cirrhosis, and genotype 1 infection [see Clinical Studies]. No safety and efficacy data are available for treatment of longer than one year. DOSAGE AND ADMINISTRATION Under no circumstances should REBETOL capsules be opened, crushed, or broken. REBETOL should be taken with food [see CLINICAL PHARMACOLOGY]. REBETOL should not be used in patients with creatinine clearance less than 50 mL/min. REBETOL/PegIntron Combination Therapy Adult Patients The recommended dose of PegIntron is 1.5 mcg/kg/week subcutaneously in combination with 800 to 1400 mg REBETOL capsules orally based on patient body weight (see Table 1). The volume of PegIntron to be injected depends on the strength of PegIntron and patient's body weight, refer to labeling for PegIntron for additional dosing information. Duration of Treatment – Interferon Alpha-naïve Patients The treatment duration for patients with genotype 1 is 48 weeks. Discontinuation of therapy should be considered in patients who do not achieve at least a 2 log10 drop or loss of HCV-RNA at 12 weeks, or if HCV-RNA remains detectable after 24 weeks of therapy. Patients with genotype 2 and 3 should be treated for 24 weeks. Duration of Treatment – Re-treatment with PegIntron/REBETOL of Prior Treatment Failures The treatment duration for patients who previously failed therapy is 48 weeks, regardless of HCV genotype. Re-treated patients who fail to achieve undetectable HCV-RNA at Week 12 of therapy, or whose HCV-RNA remains detectable after 24 weeks of therapy, are highly unlikely to achieve SVR and discontinuation of therapy should be considered [see Clinical Studies]. Table 1: Recommended Dosing for REBETOL in Combination Therapy with PegIntron (Adults) Body Weight kg (lbs) REBETOL Daily Dose REBETOL Number of Capsules < 66 ( < 144) 800 mg/day 2 x 200-mg capsules A.M. 2 x 200-mg capsules P.M. 66-80 (145-177) 1000 mg/day 2 x 200-mg capsules A.M. 3 x 200-mg capsules P.M. 81-105 (178-231) 1200 mg/day 3 x 200-mg capsules A.M. 3 x 200-mg capsules P.M. > 105 (231) 1400 mg/day 3 x 200-mg capsules A.M. 4 x 200-mg capsules P.M. Pediatric Patients Dosing for pediatric patients is determined by body surface area for PegIntron and by body weight for REBETOL. The recommended dose of PegIntron is 60 mcg/m²/week subcutaneously in combination with 15 mg/kg/day of REBETOL orally in two divided doses (see Table 2) for pediatric patients ages 3-17 years. Patients who reach their 18th birthday while receiving PegIntron/REBETOL should remain on the pediatric dosing regimen. The treatment duration for patients with genotype 1 is 48 weeks. Patients with genotype 2 and 3 should be treated for 24 weeks. Table 2: Recommended REBETOL* Dosing in Combination Therapy (Pediatrics) Body Weight kg (lbs) REBETOL Daily Dose REBETOL Number of Capsules < 47 ( < 103) 15 mg/kg/day Use REBETOL Oral Solution† 47-59 (103-131) 800 mg/day 2 x 200-mg capsules A.M. 2 x 200-mg capsules P.M. 60-73 (132-162) 1000 mg/day 2 x 200-mg capsules A.M. 3 x 200-mg capsules P.M. > 73 ( > 162) 1200 mg/day 3 x 200-mg capsules A.M. 3 x 200-mg capsules P.M. * REBETOL to be used in combination with PegIntron 60 mcg/m² weekly. † REBETOL Oral Solution may be used for any patient regardless of body weight. REBETOL/INTRON A Combination Therapy Adults Duration of Treatment – Interferon Alpha-naïve Patients The recommended dose of INTRON A is 3 million IU three times weekly subcutaneously. The recommended dose of REBETOL capsules depends on the patient's body weight (refer to Table 3). The recommended duration of treatment for patients previously untreated with interferon is 24 to 48 weeks. The duration of treatment should be individualized to the patient depending on baseline disease characteristics, response to therapy, and tolerability of the regimen [see INDICATIONS AND USAGE, ADVERSE REACTIONS, and Clinical Studies]. After 24 weeks of treatment, virologic response should be assessed. Treatment discontinuation should be considered in any patient who has not achieved an HCV-RNA below the limit of detection of the assay by 24 weeks. There are no safety and efficacy data on treatment for longer than 48 weeks in the previously untreated patient population. Duration of Treatment – Re-treatment with INTRON A/REBETOL in Relapse Patients In patients who relapse following nonpegylated interferon monotherapy, the recommended duration of treatment is 24 weeks. Table 3: Recommended Dosing Body Weight REBETOL Capsules ≤ 75 kg 2 x 200-mg capsules AM 3 x 200-mg capsules PM daily orally > 75 kg 3 x 200-mg capsules AM 3 x 200-mg capsules PM daily orally Pediatrics The recommended dose of REBETOL is 15 mg/kg per day orally (divided dose AM and PM). Refer to Table 2 for Pediatric Dosing of REBETOL in combination with INTRON A. INTRON A for Injection by body weight of 25 kg to 61 kg is 3 million IU/m² three times weekly subcutaneously. Refer to adult dosing table for greater than 61 kg body weight. The recommended duration of treatment is 48 weeks for pediatric patients with genotype 1. After 24 weeks of treatment, virologic response should be assessed. Treatment discontinuation should be considered in any patient who has not achieved an HCV-RNA below the limit of detection of the assay by this time. The recommended duration of treatment for pediatric patients with genotype 2/3 is 24 weeks. Laboratory Tests The following laboratory tests are recommended for all patients treated with REBETOL, prior to beginning treatment and then periodically thereafter. Standard hematologic tests - including hemoglobin (pretreatment, Week 2 and Week 4 of therapy, and as clinically appropriate [see WARNINGS AND PRECAUTIONS], complete and differential white blood cell counts, and platelet count. Blood chemistries - liver function tests and TSH. Pregnancy - including monthly monitoring for women of childbearing potential. ECG [see WARNINGS AND PRECAUTIONS]. Dose Modifications If severe adverse reactions or laboratory abnormalities develop during combination REBETOL/INTRON A therapy or REBETOL/PegIntron therapy, modify, or discontinue the dose until the adverse reaction abates or decreases in severity [see WARNINGS AND PRECAUTIONS]. If intolerance persists after dose adjustment, combination therapy should be discontinued. Dose reduction of PegIntron in adult patients on REBETOL/PegIntron combination therapy is accomplished in a two-step process from the original starting dose of 1.5 mcg/kg/week, to 1 mcg/kg/week, then to 0.5 mcg/kg/week, if needed. Refer to labeling for PegIntron for additional information regarding dose reduction of PegIntron. In the adult combination therapy Study 2, dose reductions occurred in 42% of subjects receiving PegIntron 1.5 mcg/kg and REBETOL 800 mg daily, including 57% of those subjects weighing 60 kg or less. In Study 4, 16% of subjects had a dose reduction of PegIntron to 1 mcg/kg in combination with REBETOL, with an additional 4% requiring the second dose reduction of PegIntron to 0.5 mcg/kg due to adverse events [see ADVERSE REACTIONS]. Dose reduction in pediatric patients is accomplished by modifying the recommended PegIntron dose in a two-step process from the original starting dose of 60 mcg/m²/week, to 40 mcg/m²/week, then to 20 mcg/m²/week, if needed (see Table 4). In the pediatric combination therapy trial, dose reductions occurred in 25% of subjects receiving PegIntron 60 mcg/m² weekly and REBETOL 15 mg/kg daily. Dose reduction in pediatric patients is accomplished by modifying the recommended REBETOL dose from the original starting dose of 15 mg/kg daily in a two-step process to 12 mg/kg/day, then to 8 mg/kg/day, if needed (see Table 4). REBETOL should not be used in patients with creatinine clearance less than 50 mL/min. Patients with impaired renal function and those over the age of 50 should be carefully monitored with respect to development of anemia [see WARNINGS AND PRECAUTIONS, Use In Specific Populations, and CLINICAL PHARMACOLOGY]. REBETOL should be administered with caution to patients with pre-existing cardiac disease. Patients should be assessed before commencement of therapy and should be appropriately monitored during therapy. If there is any deterioration of cardiovascular status, therapy should be stopped [see WARNINGS AND PRECAUTIONS]. For patients with a history of stable cardiovascular disease, a permanent dose reduction is required if the hemoglobin decreases by greater than or equal to 2 g/dL during any 4-week period. In addition, for these cardiac history patients, if the hemoglobin remains less than 12 g/dL after 4 weeks on a reduced dose, the patient should discontinue combination therapy. It is recommended that a patient whose hemoglobin level falls below 10 g/dL have his/her REBETOL dose modified or discontinued per Table 4 [see WARNINGS AND PRECAUTIONS]. Table 4: Guidelines for Dose Modification and Discontinuation of REBETOL in combination with PegIntron or INTRON A Based on Laboratory Parameters in Adults and Pediatrics Laboratory Parameters Reduce REBETOL Daily Dose (see note 1) if: Reduce PegIntron or INTRON A Dose (see note 2) if: Discontinue Therapy if: WBC N/A 1.0 to < 1.5 x 109/L < 1.0 x 109/L Neutrophils N/A 0.5 to < 0.75 x 109/L < 0.5 x 109/L Platelets N/A 25 to < 50 x 109/L (adults) < 25 x 109/L (adults) N/A 50 to < 70 x 109/L (pediatrics) < 50 x 109/L (pediatrics) Creatinine N/A N/A > 2 mg/dL (pediatrics) Hemoglobin in patients without history of cardiac disease 8.5 to < 10 g/dL N/A < 8.5 g/dL Reduce REBETOL Dose by 200 mg/day and PegIntron or INTRON A Dose by Half if: Hemoglobin in patients with history of stable cardiac disease*† > 2 g/dL decrease in hemoglobin during any four week period during treatment < 8.5 g/dL or < 12 g/dL after four weeks of dose reduction Note 1: Adult patients: 1st dose reduction of ribavirin is by 200 mg/day (except in patients receiving the 1,400 mg, dose reduction should be by 400 mg/day). If needed, 2nd dose reduction of ribavirin is by an additional 200 mg/day. Patients whose dose of ribavirin is reduced to 600 mg daily receive one 200 mg capsule in the morning and two 200 mg capsules in the evening. Pediatric patients: 1st dose reduction of ribavirin is to 12 mg/kg/day, 2nd dose reduction of ribavirin is to 8 mg/kg/day. Note 2: Adult patients treated with REBETOL and PegIntron: 1st dose reduction of PegIntron is to 1 mcg/kg/week. If needed, 2nd dose reduction of PegIntron is to 0.5 mcg/kg/week. Pediatric patients treated with REBETOL and PegIntron: 1st dose reduction of PegIntron is to 40 mcg/m²/week, 2nd dose reduction of PegIntron is to 20 mcg/m²/week. For patients on REBETOL/INTRON A combination therapy: reduce INTRON A dose by 50%. * Pediatric patients who have pre-existing cardiac conditions and experience a hemoglobin decrease greater than or equal to 2 g/dL during any 4-week period during treatment should have weekly evaluations and hematology testing. † These guidelines are for patients with stable cardiac disease. Patients with a history of significant or unstable cardiac disease should not be treated with PegIntron /REBETOL combination therapy [see WARNINGS AND PRECAUTIONS]. Refer to labeling for INTRON A or PegIntron for additional information about how to reduce an INTRON A or PegIntron dose. Discontinuation Of Dosing Adults In HCV genotype 1, interferon-alfa-naïve patients receiving PegIntron in combination with ribavirin, discontinuation of therapy is recommended if there is not at least a 2 log10 drop or loss of HCV-RNA at 12 weeks of therapy, or if HCV-RNA levels remain detectable after 24 weeks of therapy. Regardless of genotype, previously treated patients who have detectable HCV-RNA at Week 12 or 24 are highly unlikely to achieve SVR and discontinuation of therapy should be considered. Pediatrics (3-17 Years of Age) It is recommended that patients receiving PegIntron/REBETOL combination (excluding HCV Genotype 2 and 3) be discontinued from therapy at 12 weeks if their treatment Week 12 HCV-RNA dropped less than 2 log10 compared to a pretreatment or at 24 weeks if they have detectable HCV-RNA at treatment Week 24. HOW SUPPLIED Dosage Forms And Strengths REBETOL Capsules 200 mg REBETOL Oral Solution 40 mg per mL Storage And Handling REBETOL 200 mg Capsules are white, opaque capsules with REBETOL, 200 mg, and the Schering Corporation logo imprinted on the capsule shell; the capsules are packaged in a bottle containing 56 capsules (NDC 0085-1351-05), 70 capsules (NDC 0085-1385-07), and 84 capsules (NDC 0085-1194-03). REBETOL Oral Solution 40 mg per mL is a clear, colorless to pale or light yellow bubble gum-flavored liquid and it is packaged in 4-oz amber glass bottles (100 mL/bottle) with child-resistant closures (NDC 0085-1318-01). The bottle of REBETOL Capsules should be stored at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature]. REBETOL Oral Solution should be stored between 2-8°C (36-46°F) or at 25°C (77°F); excursions permitted to 15-30°C (59-86°F) [see USP Controlled Room Temperature]. REBETOL Oral Solution manufactured for: Merck Sharp & Dohme Corp., a subsidiary of Whitehouse Station, NJ 08889, USA. Manufactured by: Schering-Plough Canada, Inc.,  Pointe Claire, Quebec, Canada REBETOL Capsules manufactured by: Merck Sharp & Dohme Corp., a subsidiary of Whitehouse Station, NJ 08889, USA. Revised: Dec 2014.

INDICATIONS COPEGUS in combination with PEGASYS (peginterferon alfa-2a) is indicated for the treatment of patients 5 years of age and older with chronic hepatitis C (CHC) virus infection who have compensated liver disease and have not been previously treated with interferon alpha. The following points should be considered when initiating COPEGUS combination therapy with PEGASYS: This indication is based on clinical trials of combination therapy in patients with CHC and compensated liver disease, some of whom had histological evidence of cirrhosis (Child-Pugh class A), and in adult patients with clinically stable HIV disease and CD4 count greater than 100 cells/mm³ . This indication is based on achieving undetectable HCV RNA after treatment for 24 or 48 weeks, based on HCV genotype, and maintaining a Sustained Virologic Response (SVR) 24 weeks after the last dose. Safety and efficacy data are not available for treatment longer than 48 weeks. The safety and efficacy of COPEGUS and PEGASYS therapy have not been established in liver or other organ transplant recipients, patients with decompensated liver disease, or previous non-responders to interferon therapy. The safety and efficacy of COPEGUS therapy for the treatment of adenovirus, RSV, parainfluenza or influenza infections have not been established. COPEGUS should not be used for these indications. Ribavirin for inhalation has a separate package insert, which should be consulted if ribavirin inhalation therapy is being considered. DOSAGE AND ADMINISTRATION COPEGUS should be taken with food. COPEGUS should be given in combination with PEGASYS; it is important to note that COPEGUS should never be given as monotherapy. See PEGASYS Package Insert for all instructions regarding PEGASYS dosing and administration. Chronic Hepatitis C Monoinfection Adult Patients The recommended dose of COPEGUS tablets is provided in Table 1. The recommended duration of treatment for patients previously untreated with ribavirin and interferon is 24 to 48 weeks. The daily dose of COPEGUS is 800 mg to 1200 mg administered orally in two divided doses. The dose should be individualized to the patient depending on baseline disease characteristics (e.g., genotype), response to therapy, and tolerability of the regimen (see Table 1). Table 1 : PEGASYS and COPEGUS Dosing Recommendations Hepatitis C Virus (HCV) Genotype PEGASYS Dose* (once weekly) COPEGUS Dose (daily) Duration Genotypes 1, 4 180 mcg < 75 kg = 1000 mg ≥ 75 kg = 1200 mg 48 weeks 48 weeks Genotypes 2, 3 180 mcg 800 mg 24 weeks Genotypes 2 and 3 showed no increased response to treatment beyond 24 weeks (see Table 10). Data on genotypes 5 and 6 are insufficient for dosing recommendations. *See PEGASYS Package Insert for further details on PEGASYS dosing and administration, including dose modification in patients with renal impairment. Pediatric Patients PEGASYS is administered as 180 mcg/1.73m² x BSA once weekly subcutaneously, to a maximum dose of 180 mcg, and should be given in combination with ribavirin. The recommended treatment duration for patients with genotype 2 or 3 is 24 weeks and for other genotypes is 48 weeks. COPEGUS should be given in combination with PEGASYS. COPEGUS is available only as a 200 mg tablet and therefore the healthcare provider should determine if this sized tablet can be swallowed by the pediatric patient. The recommended doses for COPEGUS are provided in Table 2. Patients who initiate treatment prior to their 18th birthday should maintain pediatric dosing through the completion of therapy. Table 2 : COPEGUS Dosing Recommendations for Pediatric Patients Body Weight in kilograms (kg) COPEGUS Daily Dose* COPEGUS Number of Tablets 23 - 33 400 mg/day 1 x 200 mg tablet A.M. 1 x 200 mg tablet P.M. 34 - 46 600 mg/day 1 x 200 mg tablet A.M. 2 x 200 mg tablets P.M. 47 - 59 800 mg/day 2 x 200 mg tablets A.M. 2 x 200 mg tablets P.M. 60 - 74 1000 mg/day 2 x 200 mg tablets A.M. 3 x 200 mg tablets P.M. ≥ 75 1200 mg/day 3 x 200 mg tablets A.M. 3 x 200 mg tablets P.M. *approximately 15 mg/kg/day Chronic Hepatitis C With HIV Coinfection Adult Patients The recommended dose for treatment of chronic hepatitis C in patients coinfected with HIV is PEGASYS 180 mcg subcutaneous once weekly and COPEGUS 800 mg by mouth daily for a total duration of 48 weeks, regardless of HCV genotype. Dose Modifications Adult and Pediatric Patients If severe adverse reactions or laboratory abnormalities develop during combination COPEGUS/PEGASYS therapy, the dose should be modified or discontinued, if appropriate, until the adverse reactions abate or decrease in severity. If intolerance persists after dose adjustment, COPEGUS/PEGASYS therapy should be discontinued. Table 3 provides guidelines for dose modifications and discontinuation based on the patient's hemoglobin concentration and cardiac status. COPEGUS should be administered with caution to patients with pre-existing cardiac disease. Patients should be assessed before commencement of therapy and should be appropriately monitored during therapy. If there is any deterioration of cardiovascular status, therapy should be stopped [see WARNINGS AND PRECAUTIONS]. Table 3 : COPEGUS Dose Modification Guidelines in Adults and Pediatrics Body weight in kilograms (kg) Laboratory Values Hemoglobin < 10 g/dL in patients with no cardiac disease, or Decrease in hemoglobin of ≥ 2 g/dL during any 4 week period in patients with history of stable cardiac disease Hemoglobin < 8.5 g/dL in patients with no cardiac disease, or Hemoglobin < 12 g/dL despite 4 weeks at reduced dose in patients with history of stable cardiac disease Adult Patients older than 18 years of age Any weight 1 x 200 mg tablet A.M. 2 x 200 mg tablets P.M. Discontinue COPEGUS Pediatric Patients 5 to 18 years of age 23 - 33 kg 1 x 200 mg tablet A.M. Discontinue COPEGUS 34 - 46 kg 1 x 200 mg tablet A.M. 1 x 200 mg tablet P.M. 47 - 59 kg 1 x 200 mg tablet A.M. 1 x 200 mg tablet P.M. 60 - 74 kg 1 x 200 mg tablet A.M. 2 x 200 mg tablets P.M. ≥ 75 kg 1 x 200 mg tablet A.M. 2 x 200 mg tablets P.M. The guidelines for COPEGUS dose modifications outlined in this table also apply to laboratory abnormalities or adverse reactions other than decreases in hemoglobin values. Adult Patients Once COPEGUS has been withheld due to either a laboratory abnormality or clinical adverse reaction, an attempt may be made to restart COPEGUS at 600 mg daily and further increase the dose to 800 mg daily. However, it is not recommended that COPEGUS be increased to the original assigned dose (1000 mg to 1200 mg). Pediatric Patients Upon resolution of a laboratory abnormality or clinical adverse reaction, an increase in COPEGUS dose to the original dose may be attempted depending upon the physician's judgment. If COPEGUS has been withheld due to a laboratory abnormality or clinical adverse reaction, an attempt may be made to restart COPEGUS at one-half the full dose. Renal Impairment The total daily dose of COPEGUS should be reduced for patients with creatinine clearance less than or equal to 50 mL/min; and the weekly dose of PEGASYS should be reduced for creatinine clearance less than 30 mL/min as follows in Table 4 [see Use In Specific Populations, Pharmacokinetics, and PEGASYS Package Insert]. Table 4 : Dosage Modification for Renal Impairment Creatinine Clearance PEGASYS Dose (once weekly) COPEGUS Dose (daily) 30 to 50 mL/min 180 mcg Alternating doses, 200 mg and 400 mg every other day Less than 30 mL/min 135 mcg 200 mg daily Hemodialysis 135 mcg 200 mg daily The dose of COPEGUS should not be further modified in patients with renal impairment. If severe adverse reactions or laboratory abnormalities develop, COPEGUS should be discontinued, if appropriate, until the adverse reactions abate or decrease in severity. If intolerance persists after restarting COPEGUS, COPEGUS/PEGASYS therapy should be discontinued. No data are available for pediatric subjects with renal impairment. Discontinuation Of Dosing Discontinuation of PEGASYS/COPEGUS therapy should be considered if the patient has failed to demonstrate at least a 2 log10 reduction from baseline in HCV RNA by 12 weeks of therapy, or undetectable HCV RNA levels after 24 weeks of therapy. PEGASYS/COPEGUS therapy should be discontinued in patients who develop hepatic decompensation during treatment [see WARNINGS AND PRECAUTIONS]. HOW SUPPLIED Dosage Forms And Strengths COPEGUS (ribavirin) is available as a light pink to pink colored, flat, oval-shaped, film-coated tablet for oral administration. Each tablet contains 200 mg of ribavirin. COPEGUS® (ribavirin) is available as tablets for oral administration. Each tablet contains 200 mg of ribavirin and is light pink to pink colored, flat, oval-shaped, film-coated, and engraved with RIB 200 on one side and ROCHE on the other side. They are packaged as bottle of 168 tablets (NDC 0004-0086-94). Storage And Handling Store the COPEGUS®Tablets bottle at 25°C (77°F); excursions are permitted between 15°C and 30°C (59°F and 86°F) [see USP Controlled Room Temperature]. Keep bottle tightly closed. Manufactured by: Hoffmann-La Roche, Inc. c/o Genentech, Inc. A Member of the Roche Group, 1 DNA Way, South San Francisco, CA 94080-4990. Revised: Aug 2015

PATIENT INFORMATION No information provided. Please refer to the WARNINGS and PRECAUTIONS sections.

PATIENT INFORMATION No information provided. Please refer to the WARNINGS AND PRECAUTIONS section.

PATIENT INFORMATION COPEGUS® (Co-PEG-UHS) (ribavirin) Tablets Read this Medication Guide carefully before you start taking COPEGUS and read the Medication Guide each time you get more COPEGUS. There may be new information. This information does not take the place of talking to your healthcare provider about your medical condition or your treatment. Also read the Medication Guide for PEGASYS (peginterferon alfa-2a). What is the most important information I should know about COPEGUS? You should not take COPEGUS alone to treat chronic hepatitis C infection. COPEGUS should be used with PEGASYS to treat chronic hepatitis C infection. COPEGUS may cause you to have a blood problem (hemolytic anemia) that can worsen any heart problems you have, and cause you to have a heart attack or die. Tell your healthcare provider if you have ever had any heart problems. COPEGUS may not be right for you. If you have chest pain while you take COPEGUS, get emergency medical attention right away. COPEGUS may cause birth defects or death of your unborn baby. If you are pregnant or your sexual partner is pregnant, do not take COPEGUS. You or your sexual partner should not become pregnant while you take COPEGUS and for 6 months after treatment is over. You must use two forms of birth control when you take COPEGUS and for the 6 months after treatment. Females must have a pregnancy test before starting COPEGUS, every month while treated with COPEGUS, and every month for the 6 months after treatment with COPEGUS. If you or your female sexual partner becomes pregnant while taking COPEGUS or within 6 months after you stop taking COPEGUS, tell your healthcare provider right away. You or your healthcare provider should contact the Ribavirin Pregnancy Registry by calling 1-800-593-2214. The Ribavirin Pregnancy Registry collects information about what happens to mothers and their babies if the mother takes COPEGUS while she is pregnant. What is COPEGUS? COPEGUS is a prescription medicine used with another medicine called PEGASYS (peginterferon alfa-2a) to treat chronic (lasting a long time) hepatitis C infection in people 5 years and older whose liver still works normally, and who have not been treated before with a medicine called an interferon alpha. It is not known if COPEGUS is safe and will work in children under 5 years of age. Who should not take COPEGUS? See “What is the most important information I should know about COPEGUS?” Do not take COPEGUS if you: have certain types of hepatitis caused by your immune system attacking your liver (autoimmune hepatitis) have certain blood disorders, such as thalassemia major or sickle-cell anemia (hemoglobinopathies) take didanosine (Videx or Videx EC) Talk to your healthcare provider before starting treatment with COPEGUS if you have any of these medical conditions. What should I tell my healthcare provider before taking COPEGUS? Before you take COPEGUS, tell your healthcare provider if you have or have had: treatment for hepatitis C that did not work for you serious allergic reactions to COPEGUS or to any of the ingredients in COPEGUS. See the end of this Medication Guide for a list of ingredients. breathing problems. COPEGUS may cause or worsen your breathing problems you already have. vision problems. COPEGUS may cause eye problems or worsen eye problems you already have. You should have an eye exam before you start treatment with COPEGUS. certain blood disorders such as anemia high blood pressure, heart problems or have had a heart attack. Your healthcare provider should test your blood and heart before you start treatment with COPEGUS. thyroid problems diabetes. COPEGUS and PEGASYS combination therapy may make your diabetes worse or harder to treat. liver problems other than hepatitis C virus infection human immunodeficiency virus (HIV) or other immunity problems mental health problems, including depression or thoughts of suicide kidney problems an organ transplant drug addiction or abuse infection with hepatitis B virus any other medical condition are breast feeding. It is not known if COPEGUS passes into your breast milk. You and your healthcare provider should decide if you will take COPEGUS or breast-feed. Tell your healthcare provider about all the medicines you take, including prescription and non-prescription medicines, vitamins and herbal supplements. Some medicines can cause serious side effects if taken while you also take COPEGUS. Some medicines may affect how COPEGUS works or COPEGUS may affect how your other medicines work. Especially tell your healthcare provider if you take any medicines to treat HIV, including didanosine (Videx or Videx EC), or if you take azathioprine (Imuran or Azasan). Know the medicines you take. Keep a list of them to show your healthcare provider or pharmacist when you get a new medicine. How should I take COPEGUS? Take COPEGUS exactly as your healthcare provider tells you. Your healthcare provider will tell you how much COPEGUS to take and when to take it. For children 5 years of age and older your healthcare provider will prescribe the dose of COPEGUS based on weight. Take COPEGUS with food. If you miss a dose of COPEGUS, take the missed dose as soon as possible during the same day. Do not double the next dose. If you have questions about what to do, call your healthcare provider. If you take too much COPEGUS, call your healthcare provider or local Poison Control Center right away, or go the nearest hospital emergency room right away. Your healthcare provider should do blood tests before you start treatment with COPEGUS, at weeks 2 and 4 of treatment, and then as needed to see how well you are tolerating treatment and to check for side effects. Your healthcare provider may change your dose of COPEGUS based on blood test results or side effects you may have. If you have heart problems, your healthcare provider should check your heart by doing an electrocardiogram before you start treatment with COPEGUS, and if needed during treatment. What should I avoid while taking COPEGUS? COPEGUS can make you feel tired, dizzy, or confused. You should not drive or operate machinery if you have any of these symptoms. Do not drink alcohol, including beer, wine, and liquor. This may make your liver disease worse. What are the possible side effects of COPEGUS? COPEGUS may cause serious side effects including: See “What is the most important information I should know about COPEGUS?” Swelling and irritation of your pancreas (pancreatitis). You may have stomach pain, nausea, vomiting or diarrhea. Severe allergic reactions. Symptoms may include hives, wheezing, trouble breathing, chest pain, swelling of your mouth, tongue, or lips, or severe rash. Serious breathing problems. Difficulty breathing may be a sign of a serious lung infection (pneumonia) that can lead to death. Serious eye problems that may lead to vision loss or blindness. Liver problems. Some people may get worsening of liver function. Tell your healthcare provider right away if you have any of these symptoms: stomach bloating, confusion, brown urine, and yellow eyes. Severe depression Suicidal thoughts and attempts Effect on growth in children. Children can experience a delay in weight gain and height increase while being treated with PEGASYS and COPEGUS. Catch-up in growth happens after treatment stops, but some children may not reach the height that they were expected to have before treatment. Talk to your healthcare provider if you are concerned about your child's growth during treatment with PEGASYS and COPEGUS. Call your healthcare provider or get medical help right away if you have any of the symptoms listed above. These may be signs of a serious side effect of COPEGUS treatment. Common side effects of COPEGUS taken with PEGASYS include: flu-like symptoms-feeling tired, headache, shaking along with high temperature (fever), and muscle or joint aches mood changes, feeling irritable, anxiety, and difficulty sleeping loss of appetite, nausea, vomiting, and diarrhea hair loss itching Tell your healthcare provider about any side effect that bothers you or that does not go away. These are not all the possible side effects of COPEGUS treatment. For more information, ask your healthcare provider or pharmacist. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may also report side effects to Genentech at 1-888-835-2555. How should I store COPEGUS? Store COPEGUS tablets between 59°F and 86°F (15°C and 30°C). Keep the bottle tightly closed. Keep COPEGUS and all medicines out of the reach of children. General information about the safe and effective use of COPEGUS It is not known if treatment with COPEGUS in combination with PEGASYS will prevent an infected person from spreading the hepatitis C virus to another person while on treatment. Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. Do not use COPEGUS for a condition for which it was not prescribed. Do not give COPEGUS to other people, even if they have the same symptoms that you have. It may harm them. This Medication Guide summarizes the most important information about COPEGUS. If you would like more information, talk with your healthcare provider. You can ask your healthcare provider or pharmacist for information about COPEGUS that is written for healthcare professionals. What are the ingredients in COPEGUS? Active Ingredient: ribavirin Inactive Ingredients: The core of the tablet contains pregelatinized starch, microcrystalline cellulose, sodium starch glycolate, cornstarch, and magnesium stearate. The coating of the tablet contains Chromatone-P or Opadry Pink (made by using hydroxypropyl methyl cellulose, talc, titanium dioxide, synthetic yellow iron oxide, and synthetic red iron oxide), ethyl cellulose (ECD-30), and triacetin. This Medication Guide has been approved by the U.S. Food and Drug Administration.

OVERDOSE No overdosage with VIRAZOLE (ribavirin) by aerosol administration has been reported in humans. The LDM in mice is 2 g orally and is associated with hypoactivity and gastrointestinal symptoms (estimated human equivalent dose of 0.17 g/kg, based on body surface area conversion). The mean plasma half-life after administration of aerosolized VIRAZOLE (ribavirin) for pediatric patients is 9.5 hours. VIRAZOLE (ribavirin) is concentrated and persists in red blood cells for the life of the erythrocyte (see Pharmacokinetics). CONTRAINDICATIONS VIRAZOLE (ribavirin) is contraindicated in individuals who have shown Hypersensitivity to the drug or its components, and in women who are or may become pregnant during exposure to the drug. Ribavirin has demonstrated significant teratogenic and/or embryocidal potential in all animal species in which adequate studies have been conducted (rodents and rabbits). Therefore, although clinical studies have not been performed, it should be assumed that VIRAZOLE (ribavirin) may cause fetal harm in humans. Studies in which the drug has been administered systemically demonstrate that ribavirin is concentrated in the red blood cells and persists for the life of the erythrocyte.

SIDE EFFECTS The description of adverse reactions is based on events from clinical studies (approximately 200 patients) conducted prior to 1986, and the controlled trial of aerosolized VIRAZOLE (ribavirin) conducted in 1989-1990. Additional data from spontaneous post-marketing reports of adverse events in individual patients have been available since 1986. Deaths Deaths during or shortly after treatment with aerosolized VIRAZOLE (ribavirin) have been reported in 20 cases of patients treated with VIRAZOLE (ribavirin) (12 of these patients were being treated for RSV infections). Several cases have been characterized as "possibly related" to VIRAZOLE (ribavirin) by the treating physician; these were in infants who experienced worsening respiratory status related to bronchospasm while being treated with the drug. Several other cases have been attributed to mechanical ventilator malfunction in which VIRAZOLE (ribavirin) precipitation within the ventilator apparatus led to excessively high pulmonary pressures and diminished oxygenation. In these cases the monitoring procedures described in the current package insert were not employed (see Description of Studies, WARNINGS, and DOSAGE AND ADMINISTRATION). Pulmonary and Cardiovascular Pulmonary function significantly deteriorated during aerosolized VIRAZOLE (ribavirin) treatment in six of six adults with chronic obstructive lung disease and in four of six asthmatic adults. Dyspnea and chest soreness were also reported in the latter group. Minor abnormalities in pulmonary function were also seen in healthy adult volunteers. In the original study population of approximately 200 infants who received aerosolized VIRAZOLE (ribavirin) , several serious adverse events occurred in severely ill infants with life-threatening underlying diseases, many of whom required assisted ventilation. The role of VIRAZOLE (ribavirin) in these events is indeterminate. Since the drug's approval in 1986, additional reports of similar serious, though non-fatal, events have been filed infrequently. Events associated with aerosolized VIRAZOLE (ribavirin) use have included the following: Pulmonary: Worsening of respiratory status, bronchospasm, pulmonary edema, hypoventilation, cyanosis, dyspnea, bacterial pneumonia, pneumothorax, apnea, atelectasis and ventilator dependence. Cardiovascular: Cardiac arrest, hypotension, bradycardia and digitalis toxicity. Bigeminy, bradycardia and tachycardia have been described in patients with underlying congenital heart disease. Some subjects requiring assisted ventilation experienced serious difficulties, due to inadequate ventilation and gas exchange. Precipitation of drug within the ventilatory apparatus, including the endotracheal tube, has resulted in increased positive end expiratory pressure and increased positive inspiratory pressure. Accumulation of fluid in tubing ("rain out") has also been noted. Measures to avoid these complications should be followed carefully (see DOSAGE AND ADMINISTRATION). Hematologic Although anemia was not reported with use of aerosolized VIRAZOLE (ribavirin) in controlled clinical trials, most infants treated with the aerosol have not been evaluated 1 to 2 weeks post-treatment when anemia is likely to occur. Anemia has been shown to occur frequently with experimental oral and intravenous VIRAZOLE (ribavirin) in humans. Also, cases of anemia (type unspecified), reticulocytosis and hemolytic anemia associated with aerosolized VIRAZOLE (ribavirin) use have been reported through post-marketing reporting systems. All have been reversible with discontinuation of the drug. Other Rash and conjunctivitis have been associated with the use of aerosolized VIRAZOLE (ribavirin) . These usually resolve within hours of discontinuing therapy. Seizures and asthenia associated with experimental intravenous VIRAZOLE (ribavirin) therapy have also been reported. Adverse Events in Health Care Workers Studies of environmental exposure to aerosolized VIRAZOLE (ribavirin) in health care workers administering care to patients receiving the drug have not detected adverse signs or symptoms related to exposure. However, 152 health care workers have reported experiencing adverse events through post-marketing surveillance. Nearly all were in individuals providing direct care to infants receiving aerosolized VIRAZOLE (ribavirin) . Of 358 events from these 152 individual health care worker reports, the most common signs and symptoms were headache (51% of reports), conjunctivitis (32%), and rhinitis, nausea, rash, dizziness, pharyngitis, or lacrimation (10-20% each). Several cases of bronchospasm and/or chest pain were also reported, usually in individuals with known underlying reactive airway disease. Several case reports of damage to contact lenses after prolonged close exposure to aerosolized VIRAZOLE (ribavirin) have also been reported. Most signs and symptoms reported as having occurred in exposed health care workers resolved within minutes to hours of discontinuing close exposure to aerosolized VIRAZOLE (ribavirin) (also see Information for Health Care Personnel). The symptoms of RSV in adults can include headache, conjunctivitis, sore throat and/or cough, fever, hoarseness, nasal congestion and wheezing, although RSV infections in adults are typically mild and transient. Such infections represent a potential hazaid to uninfected hospital patients. It is unknown whether certain symptoms cited in reports from health care workers were due to exposure to the drug or infection with RSV. Hospitals should implement appropriate infection control procedures. DRUG INTERACTIONS Clinical studies of interactions of VIRAZOLE (ribavirin) with other drugs commonly used to treat infants with RSV infections, such as digoxin, bronchodilators, other antiviral agents, antibiotics or anti-metabolites, have not been conducted. Interference by VIRAZOLE (ribavirin) with laboratory tests has not been evaluated.

SIDE EFFECTS Clinical trials with REBETOL in combination with PegIntron or INTRON A have been conducted in over 7800 subjects from 3 to 76 years of age. The primary toxicity of ribavirin is hemolytic anemia. Reductions in hemoglobin levels occurred within the first 1 to 2 weeks of oral therapy. Cardiac and pulmonary reactions associated with anemia occurred in approximately 10% of patients [see WARNINGS AND PRECAUTIONS]. Greater than 96% of all subjects in clinical trials experienced one or more adverse reactions. The most commonly reported adverse reactions in adult subjects receiving PegIntron or INTRON A in combination with REBETOL were injection site inflammation/reaction, fatigue/asthenia, headache, rigors, fevers, nausea, myalgia and anxiety/emotional lability/irritability. The most common adverse reactions in pediatric subjects, ages 3 and older, receiving REBETOL in combination with PegIntron or INTRON A were pyrexia, headache, neutropenia, fatigue, anorexia, injection site erythema, and vomiting. The Adverse Reactions section references the following clinical trials: REBETOL/PegIntron Combination therapy trials: Clinical Study 1 – evaluated PegIntron monotherapy (not further described in this label; see labeling for PegIntron for information about this trial). Study 2 – evaluated REBETOL 800 mg/day flat dose in combination with 1.5 mcg/kg/week PegIntron or with INTRON A. Study 3 – evaluated PegIntron/weight-based REBETOL in combination with PegIntron/flat dose REBETOL regimen. Study 4 – compared two PegIntron (1.5 mcg/kg/week and 1 mcg/kg/week) doses in combination with REBETOL and a third treatment group receiving Pegasys® (180 mcg/week)/Copegus® (1000-1200 mg/day). Study 5 – evaluated PegIntron (1.5 mcg/kg/week) in combination with weight-based REBETOL in prior treatment failure subjects. PegIntron/REBETOL Combination Therapy in Pediatric Patients REBETOL/INTRON A Combination Therapy trials for adults and pediatrics Serious adverse reactions have occurred in approximately 12% of subjects in clinical trials with PegIntron with or without REBETOL [see BOXED WARNING, WARNINGS AND PRECAUTIONS]. The most common serious events occurring in subjects treated with PegIntron and REBETOL were depression and suicidal ideation [see WARNINGS AND PRECAUTIONS], each occurring at a frequency of less than 1%. Suicidal ideation or attempts occurred more frequently among pediatric patients, primarily adolescents, compared to adult patients (2.4% versus 1%) during treatment and off-therapy follow-up [see WARNINGS AND PRECAUTIONS]. The most common fatal reaction occurring in subjects treated with PegIntron and REBETOL was cardiac arrest, suicide ideation, and suicide attempt [see WARNINGS AND PRECAUTIONS], all occurring in less than 1% of subjects. Because clinical trials are conducted under widely varying conditions, adverse reactions rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Clinical Trials Experience – REBETOL/PegIntron Combination Therapy Adult Subjects Adverse reactions that occurred in the clinical trial at greater than 5% incidence are provided by treatment group from the REBETOL/PegIntron Combination Therapy (Study 2) in Table 5. Table 5: Adverse Reactions Occurring in Greater Than 5% of Adult Subjects Adverse Reactions Percentage of Subjects Reporting Adverse Reactions* Adverse Reactions Percentage of Subjects Reporting Adverse Reactions* PegIntron 1.5 mcg/kg/ REBETOL (N=511) INTRON A/ REBETOL (N=505) PegIntron 1.5 mcg/kg/ REBETOL (N=511) INTRON A/ REBETOL (N=505) Application Site Musculoskeletal Injection Site Inflammation 25 18 Myalgia 56 50 Injection Site Reaction 58 36 Arthralgia 34 28 Autonomic Nervous System Musculoskeletal Pain 21 19 Dry Mouth 12 8 Psychiatric Increased Sweating 11 7 Insomnia 40 41 Flushing 4 3 Depression 31 34 Body as a Whole Anxiety/Emotional 47 47 Lability/Irritability Fatigue/Asthenia 66 63 Concentration Impaired 17 21 Headache 62 58 Agitation 8 5 Rigors 48 41 Nervousness 6 6 Fever 46 33 Reproductive, Female Weight Loss 29 20 Menstrual Disorder 7 6 Right Upper Quadrant Pain 12 6 Resistance Mechanism Chest Pain 8 7 Viral Infection 12 12 Malaise 4 6 Fungal Infection 6 1 Central/Peripheral Nervous System Respiratory System Dizziness 21 17 Dyspnea 26 24 Endocrine Coughing 23 16 Hypothyroidism 5 4 Pharyngitis 12 13 Gastrointestinal Rhinitis 8 6 Nausea 43 33 Sinusitis 6 5 Anorexia 32 27 Skin and Appendages Diarrhea 22 17 Alopecia 36 32 Vomiting 14 12 Pruritus 29 28 Abdominal Pain 13 13 Rash 24 23 Dyspepsia 9 8 Skin Dry 24 23 Constipation 5 5 Special Senses, Other Hematologic Disorders Taste Perversion 9 4 Neutropenia 26 14 Vision Disorders Anemia 12 17 Vision Blurred 5 6 Leukopenia 6 5 Conjunctivitis 4 5 Thrombocytopenia 5 2 Liver and Biliary System Hepatomegaly 4 4 * A subject may have reported more than one adverse reaction within a body system/organ class category. Table 6 summarizes the treatment-related adverse reactions in Study 4 that occurred at a greater than or equal to 10% incidence. Table 6: Treatment-Related Adverse Reactions (Greater Than or Equal to 10% Incidence) By Descending Frequency Adverse Reactions Study 4 Percentage of Subjects Reporting Treatment-Related Adverse Reactions PegIntron 1.5 mcg/kg with REBETOL (N=1019) PegIntron 1 mcg/kg with REBETOL (N=1016) Pegasys 180 mcg with Copegus (N=1035) Fatigue 67 68 64 Headache 50 47 41 Nausea 40 35 34 Chills 39 36 23 Insomnia 38 37 41 Anemia 35 30 34 Pyrexia 35 32 21 Injection Site Reactions 34 35 23 Anorexia 29 25 21 Rash 29 25 34 Myalgia 27 26 22 Neutropenia 26 19 31 Irritability 25 25 25 Depression 25 19 20 Alopecia 23 20 17 Dyspnea 21 20 22 Arthralgia 21 22 22 Pruritus 18 15 19 Influenza-like Illness 16 15 15 Dizziness 16 14 13 Diarrhea 15 16 14 Cough 15 16 17 Weight Decreased 13 10 10 Vomiting 12 10 9 Unspecified Pain 12 13 9 Dry Skin 11 11 12 Anxiety 11 11 10 Abdominal Pain 10 10 10 Leukopenia 9 7 10 The incidence of serious adverse reactions was comparable in all trials. In Study 3, there was a similar incidence of serious adverse reactions reported for the weight-based REBETOL group (12%) and for the flat-dose REBETOL regimen. In Study 2, the incidence of serious adverse reactions was 17% in the PegIntron/REBETOL groups compared to 14% in the INTRON A/REBETOL group. In many but not all cases, adverse reactions resolved after dose reduction or discontinuation of therapy. Some subjects experienced ongoing or new serious adverse reactions during the 6-month follow-up period. In Study 2, many subjects continued to experience adverse reactions several months after discontinuation of therapy. By the end of the 6-month follow-up period, the incidence of ongoing adverse reactions by body class in the PegIntron 1.5/REBETOL group was 33% (psychiatric), 20% (musculoskeletal), and 10% (for endocrine and for GI). In approximately 10 to 15% of subjects, weight loss, fatigue, and headache had not resolved. There have been 31 subject deaths that occurred during treatment or during follow-up in these clinical trials. In Study 1, there was 1 suicide in a subject receiving PegIntron monotherapy and 2 deaths among subjects receiving INTRON A monotherapy (1 murder/suicide and 1 sudden death). In Study 2, there was 1 suicide in a subject receiving PegIntron/REBETOL combination therapy; and 1 subject death in the INTRON A/REBETOL group (motor vehicle accident). In Study 3, there were 14 deaths, 2 of which were probable suicides and 1 was an unexplained death in a person with a relevant medical history of depression. In Study 4, there were 12 deaths, 6 of which occurred in subjects who received PegIntron/REBETOL combination therapy, 5 in the PegIntron 1.5 mcg/REBETOL arm (N=1019) and 1 in the PegIntron 1 mcg/REBETOL arm (N=1016), and 6 of which occurred in subjects receiving Pegasys/Copegus (N=1035); there were 3 suicides that occurred during the off treatment follow-up period in subjects who received PegIntron (1.5 mcg/kg)/REBETOL combination therapy. In Studies 1 and 2, 10 to 14% of subjects receiving PegIntron, alone or in combination with REBETOL, discontinued therapy compared with 6% treated with INTRON A alone and 13% treated with INTRON A in combination with REBETOL. Similarly in Study 3, 15% of subjects receiving PegIntron in combination with weight-based REBETOL and 14% of subjects receiving PegIntron and flat dose REBETOL discontinued therapy due to an adverse reaction. The most common reasons for discontinuation of therapy were related to known interferon effects of psychiatric, systemic (e.g., fatigue, headache), or gastrointestinal adverse reactions. In Study 4, 13% of subjects in the PegIntron 1.5 mcg/REBETOL arm, 10% in the PegIntron 1 mcg/REBETOL arm and 13% in the Pegasys 180 mcg/Copegus arm discontinued due to adverse events. In Study 2, dose reductions due to adverse reactions occurred in 42% of subjects receiving PegIntron (1.5 mcg/kg)/REBETOL and in 34% of those receiving INTRON A/REBETOL. The majority of subjects (57%) weighing 60 kg or less receiving PegIntron (1.5 mcg/kg)/REBETOL required dose reduction. Reduction of interferon was dose-related (PegIntron 1.5 mcg/kg greater than PegIntron 0.5 mcg/kg or INTRON A), 40%, 27%, 28%, respectively. Dose reduction for REBETOL was similar across all three groups, 33 to 35%. The most common reasons for dose modifications were neutropenia (18%), or anemia (9%) (see Laboratory Values). Other common reasons included depression, fatigue, nausea, and thrombocytopenia. In Study 3, dose modifications due to adverse reactions occurred more frequently with weight-based dosing (WBD) compared to flat dosing (29% and 23%, respectively). In Study 4, 16% of subjects had a dose reduction of PegIntron to 1 mcg/kg in combination with REBETOL, with an additional 4% requiring the second dose reduction of PegIntron to 0.5 mcg/kg due to adverse events compared to 15% of subjects in the Pegasys/Copegus arm, who required a dose reduction to 135 mcg/week with Pegasys, with an additional 7% in the Pegasys/Copegus arm requiring second dose reduction to 90 mcg/week with Pegasys. In the PegIntron/REBETOL combination trials the most common adverse reactions were psychiatric, which occurred among 77% of subjects in Study 2 and 68% to 69% of subjects in Study 3. These psychiatric adverse reactions included most commonly depression, irritability, and insomnia, each reported by approximately 30% to 40% of subjects in all treatment groups. Suicidal behavior (ideation, attempts, and suicides) occurred in 2% of all subjects during treatment or during follow-up after treatment cessation [see WARNINGS AND PRECAUTIONS]. In Study 4, psychiatric adverse reactions occurred in 58% of subjects in the PegIntron 1.5 mcg/REBETOL arm, 55% of subjects in the PegIntron 1 mcg/REBETOL arm, and 57% of subjects in the Pegasys 180 mcg/Copegus arm. PegIntron induced fatigue or headache in approximately two-thirds of subjects, with fever or rigors in approximately half of the subjects. The severity of some of these systemic symptoms (e.g., fever and headache) tended to decrease as treatment continued. In Studies 1 and 2, application site inflammation and reaction (e.g., bruise, itchiness, and irritation) occurred at approximately twice the incidence with PegIntron therapies (in up to 75% of subjects) compared with INTRON A. However, injection site pain was infrequent (2 to 3%) in all groups. In Study 3, there was a 23% to 24% incidence overall for injection site reactions or inflammation. Subjects receiving REBETOL/PegIntron as re-treatment after failing a previous interferon combination regimen reported adverse reactions similar to those previously associated with this regimen during clinical trials of treatment-naïve subjects. Pediatric Subjects In general, the adverse-reaction profile in the pediatric population was similar to that observed in adults. In the pediatric trial, the most prevalent adverse reactions in all subjects were pyrexia (80%), headache (62%), neutropenia (33%), fatigue (30%), anorexia (29%), injection-site erythema (29%) and vomiting (27%). The majority of adverse reactions reported in the trial were mild or moderate in severity. Severe adverse reactions were reported in 7% (8/107) of all subjects and included injection site pain (1%), pain in extremity (1%), headache (1%), neutropenia (1%), and pyrexia (4%). Important adverse reactions that occurred in this subject population were nervousness (7%; 7/107), aggression (3%; 3/107), anger (2%; 2/107), and depression (1%; 1/107). Five subjects received levothyroxine treatment, three with clinical hypothyroidism and two with asymptomatic TSH elevations. Weight and height gain of pediatric subjects treated with PegIntron plus REBETOL lagged behind that predicted by normative population data for the entire length of treatment. Severely inhibited growth velocity (less than 3rd percentile) was observed in 70% of the subjects while on treatment. Dose modifications of PegIntron and/or ribavirin were required in 25% of subjects due to treatment-related adverse reactions, most commonly for anemia, neutropenia and weight loss. Two subjects (2%; 2/107) discontinued therapy as the result of an adverse reaction. Adverse reactions that occurred with a greater than or equal to 10% incidence in the pediatric trial subjects are provided in Table 7. Table 7: Percentage of Pediatric Subjects with Treatment-Related Adverse Reactions (in At Least 10% of All Subjects) System Organ Class Preferred Term All Subjects (N=107) Blood and Lymphatic System Disorders Neutropenia 33% Anemia 11% Leukopenia 10% Gastrointestinal Disorders Abdominal Pain 21% Abdominal Pain Upper 12% Vomiting 27% Nausea 18% General Disorders and Administration Site Conditions Pyrexia 80% Fatigue 30% Injection-site Erythema 29% Chills 21% Asthenia 15% Irritability 14% Investigations Weight Loss 19% Metabolism and Nutrition Disorders Anorexia 29% Decreased Appetite 22% Musculoskeletal and Connective Tissue Disorders Arthralgia 17% Myalgia 17% Nervous System Disorders Headache 62% Dizziness 14% Skin and Subcutaneous Tissue Disorders Alopecia 17% Ninety-four of 107 subjects enrolled in a 5 year long-term follow-up trial. The long-term effects on growth were less in those subjects treated for 24 weeks than those treated for 48 weeks. Twenty-four percent of subjects (11/46) treated for 24 weeks and 40% of subjects (19/48) treated for 48 weeks had a > 15 percentile height-for-age decrease from pre-treatment to the end of 5 year long-term follow-up compared to pre-treatment baseline percentiles. Eleven percent of subjects (5/46) treated for 24 weeks and 13% of subjects (6/48) treated for 48 weeks were observed to have a decrease from pre-treatment baseline of > 30 height-for-age percentiles to the end of the 5 year long-term follow-up. While observed across all age groups, the highest risk for reduced height at the end of long-term follow-up appeared to correlate with initiation of combination therapy during the years of expected peak growth velocity. [See WARNINGS AND PRECAUTIONS] Laboratory Values Adult and Pediatric Subjects The adverse reaction profile in Study 3, which compared PegIntron/weight-based REBETOL combination to a PegIntron/flat dose REBETOL regimen, revealed an increased rate of anemia with weight-based dosing (29% vs. 19% for weight-based vs. flat dose regimens, respectively). However, the majority of cases of anemia were mild and responded to dose reductions. Changes in selected laboratory values during treatment in combination with REBETOL treatment are described below. Decreases in hemoglobin, leukocytes, neutrophils, and platelets may require dose reduction or permanent discontinuation from therapy [see DOSAGE AND ADMINISTRATION]. Changes in selected laboratory values during therapy are described in Table 8. Most of the changes in laboratory values in the PegIntron/REBETOL trial with pediatrics were mild or moderate. Table 8: Selected Laboratory Abnormalities During Treatment with REBETOL and PegIntron or REBETOL and INTRON A in Previously Untreated Subjects Laboratory Parameters* Percentage of Subjects Adults (Study 2) Pediatrics PegIntron/ REBETOL (N=511) INTRON A/ REBETOL (N=505) PegIntron/ REBETOL (N=107)* Hemoglobin (g/dL) 9.5 to < 11.0 26 27 30 8.0 to < 9.5 3 3 2 6.5-7.9 0.2 0.2 - Leukocytes (x 109/L) 2.0-2.9 46 41 39 1.5 to < 2.0 24 8 3 1.0-1.4 5 1 - Neutrophils (x 109/L) 1.0-1.5 33 37 35 0.75 to < 1.0 25 13 26 0.5 to < 0.75 18 7 13 < 0.5 4 2 3 Platelets (x 109/L) 70-100 15 5 1 50 to < 70 3 0.8 - 30-49 0.2 0.2 - 25 to < 50 - - 1 Total Bilirubin (mg/dL) (μmole/L) 1.5-3.0 10 13 - 1.26-2.59 x ULN† - - 7 3.1-6.0 0.6 0.2 - 2.6-5 x ULN† - - - 6.1-12.0 0 0.2 - ALT (U/L) 2 x Baseline 0.6 0.2 1 2.1-5 x Baseline 3 1 5 5.1-10 x Baseline 0 0 3 * The table summarizes the worst category observed within the period per subject per laboratory test. Only subjects with at least one treatment value for a given laboratory test are included. † ULN=Upper limit of normal. Hemoglobin Hemoglobin levels decreased to less than 11 g/dL in about 30% of subjects in Study 2. In Study 3, 47% of subjects receiving WBD REBETOL and 33% on flat-dose REBETOL had decreases in hemoglobin levels less than 11 g/dl. Reductions in hemoglobin to less than 9 g/dL occurred more frequently in subjects receiving WBD compared to flat dosing (4% and 2%, respectively). In Study 2, dose modification was required in 9% and 13% of subjects in the PegIntron/REBETOL and INTRON A/REBETOL groups. In Study 4, subjects receiving PegIntron (1.5 mcg/kg)/REBETOL had decreases in hemoglobin levels to between 8.5 to less than 10 g/dL (28%) and to less than 8.5 g/dL (3%), whereas in patients receiving Pegasys 180 mcg/Copegus these decreases occurred in 26% and 4% of subjects respectively. Hemoglobin levels became stable by treatment Weeks 4-6 on average. The typical pattern observed was a decrease in hemoglobin levels by treatment Week 4 followed by stabilization and a plateau, which was maintained to the end of treatment. In the PegIntron monotherapy trial, hemoglobin decreases were generally mild and dose modifications were rarely necessary [see DOSAGE AND ADMINISTRATION]. Neutrophils Decreases in neutrophil counts were observed in a majority of adult subjects treated with combination therapy with REBETOL in Study 2 (85%) and INTRON A/REBETOL (60%). Severe potentially life-threatening neutropenia (less than 0.5 x 109/L) occurred in 2% of subjects treated with INTRON A/REBETOL and in approximately 4% of subjects treated with PegIntron/REBETOL in Study 2. Eighteen percent of subjects receiving PegIntron/REBETOL in Study 2 required modification of interferon dosage. Few subjects (less than 1%) required permanent discontinuation of treatment. Neutrophil counts generally returned to pre-treatment levels 4 weeks after cessation of therapy [see DOSAGE AND ADMINISTRATION]. Platelets Platelet counts decreased to less than 100,000/mm³ in approximately 20% of subjects treated with PegIntron alone or with REBETOL and in 6% of adult subjects treated with INTRON A/REBETOL. Severe decreases in platelet counts (less than 50,000/mm³) occur in less than 4% of adult subjects. Patients may require discontinuation or dose modification as a result of platelet decreases [see DOSAGE AND ADMINISTRATION]. In Study 2, 1% or 3% of subjects required dose modification of INTRON A or PegIntron, respectively. Platelet counts generally returned to pretreatment levels 4 weeks after the cessation of therapy. Thyroid Function Development of TSH abnormalities, with or without clinical manifestations, is associated with interferon therapies. In Study 2, clinically apparent thyroid disorders occurred among subjects treated with either INTRON A or PegIntron (with or without REBETOL) at a similar incidence (5% for hypothyroidism and 3% for hyperthyroidism). Subjects developed new onset TSH abnormalities while on treatment and during the follow-up period. At the end of the follow-up period 7% of subjects still had abnormal TSH values. Bilirubin and Uric Acid In Study 2, 10 to 14% of subjects developed hyperbilirubinemia and 33 to 38% developed hyperuricemia in association with hemolysis. Six subjects developed mild to moderate gout. Clinical Trials Experience – REBETOL/INTRON A Combination Therapy Adult Subjects In clinical trials, 19% and 6% of previously untreated and relapse subjects, respectively, discontinued therapy due to adverse reactions in the combination arms compared to 13% and 3% in the interferon arms. Selected treatment-related adverse reactions that occurred in the US trials with greater than or equal to 5% incidence are provided by treatment group (see Table 9). In general, the selected treatment-related adverse reactions were reported with lower incidence in the international trials as compared to the US trials, with the exception of asthenia, influenza-like symptoms, nervousness, and pruritus. Pediatric Subjects In clinical trials of 118 pediatric subjects 3 to 16 years of age, 6% discontinued therapy due to adverse reactions. Dose modifications were required in 30% of subjects, most commonly for anemia and neutropenia. In general, the adverse-reaction profile in the pediatric population was similar to that observed in adults. Injection site disorders, fever, anorexia, vomiting, and emotional lability occurred more frequently in pediatric subjects compared to adult subjects. Conversely, pediatric subjects experienced less fatigue, dyspepsia, arthralgia, insomnia, irritability, impaired concentration, dyspnea, and pruritus compared to adult subjects. Selected treatment-related adverse reactions that occurred with greater than or equal to 5% incidence among all pediatric subjects who received the recommended dose of REBETOL/INTRON A combination therapy are provided in Table 9. Table 9: Selected Treatment-Related Adverse Reactions: Previously Untreated and Relapse Adult Subjects and Previously Untreated Pediatric Subjects Subjects Reporting Adverse Reactions* Percentage of Subjects US Previously Untreated Study US Relapse Study Pediatric Subjects 24 weeks of treatment 48 weeks of treatment 24 weeks of treatment 48 weeks of treatment INTRON A/REBETOL (N=228) INTRON A/Placebo (N=231) INTRON A/REBETOL (N=228) INTRON A/Placebo (N=225) INTRON A/REBETOL (N=77) INTRON A/Placebo (N=76) INTRON A/REBETOL (N=118) Application Site Disorders Injection Site Inflammation 13 10 12 14 6 8 14 Injection Site Reaction 7 9 8 9 5 3 19 Body as a Whole - General Disorders Headache 63 63 66 67 66 68 69 Fatigue 68 62 70 72 60 53 58 Rigors 40 32 42 39 43 37 25 Fever 37 35 41 40 32 36 61 Influenza-like Symptoms 14 18 18 20 13 13 31 Asthenia 9 4 9 9 10 4 5 Chest Pain 5 4 9 8 6 7 5 Central & Peripheral Nervous System Disorders Dizziness 17 15 23 19 26 21 20 Gastrointestinal System Disorders Nausea 38 35 46 33 47 33 33 Anorexia 27 16 25 19 21 14 51 Dyspepsia 14 6 16 9 16 9 < 1 Vomiting 11 10 9 13 12 8 42 Musculoskeletal System Disorders Myalgia 61 57 64 63 61 58 32 Arthralgia 30 27 33 36 29 29 15 Musculoskeletal Pain 20 26 28 32 22 28 21 Psychiatric Disorders Insomnia 39 27 39 30 26 25 14 Irritability 23 19 32 27 25 20 10 Depression 32 25 36 37 23 14 13 Emotional Lability 7 6 11 8 12 8 16 Concentration Impaired 11 14 14 14 10 12 5 Nervousness 4 2 4 4 5 4 3 Respiratory System Disorders Dyspnea 19 9 18 10 17 12 5 Sinusitis 9 7 10 14 12 7 < 1 Skin and Appendages Disorders Alopecia 28 27 32 28 27 26 23 Rash 20 9 28 8 21 5 17 Pruritus 21 9 19 8 13 4 12 Special Senses, Other Disorders Taste Perversion 7 4 8 4 6 5 < 1 * Subjects reporting one or more adverse reactions. A subject may have reported more than one adverse reaction within a body system/organ class category. During a 48-week course of therapy there was a decrease in the rate of linear growth (mean percentile assignment decrease of 7%) and a decrease in the rate of weight gain (mean percentile assignment decrease of 9%). A general reversal of these trends was noted during the 24-week post-treatment period. Long-term data in a limited number of patients, however, suggests that combination therapy may induce a growth inhibition that results in reduced final adult height in some patients [see WARNINGS AND PRECAUTIONS]. Laboratory Values Changes in selected hematologic values (hemoglobin, white blood cells, neutrophils, and platelets) during therapy are described below (see Table 10). Hemoglobin. Hemoglobin decreases among subjects receiving REBETOL therapy began at Week 1, with stabilization by Week 4. In previously untreated subjects treated for 48 weeks, the mean maximum decrease from baseline was 3.1 g/dL in the US trial and 2.9 g/dL in the international trial. In relapse subjects, the mean maximum decrease from baseline was 2.8 g/dL in the US trial and 2.6 g/dL in the international trial. Hemoglobin values returned to pretreatment levels within 4 to 8 weeks of cessation of therapy in most subjects. Bilirubin and Uric Acid. Increases in both bilirubin and uric acid, associated with hemolysis, were noted in clinical trials. Most were moderate biochemical changes and were reversed within 4 weeks after treatment discontinuation. This observation occurred most frequently in subjects with a previous diagnosis of Gilbert's syndrome. This has not been associated with hepatic dysfunction or clinical morbidity. Table 10: Selected Laboratory Abnormalities During Treatment With REBETOL and INTRON A: Previously Untreated and Relapse Adult Subjects and Previously Untreated Pediatric Subjects Percentage of Subjects US Previously Untreated Study US Relapse Study Pediatric Subjects 24 weeks of treatment 48 weeks of treatment 24 weeks of treatment 48 weeks of treatment INTRON A/REBETOL (N=228) INTRON A/Placebo (N=231) INTRONA/ REBETOL (N=228) INTRON A/Placebo (N=225) INTRON A/REBETOL (N=77) INTRON A/Placebo (N=76) INTRON A/ REBETOL (N=118) Hemoglobin (g/dL) 9.5 to 10.9 24 1 32 1 21 3 24 8.0 to 9.4 5 0 4 0 4 0 3 6.5 to 7.9 0 0 0 0.4 0 0 0 < 6.5 0 0 0 0 0 0 0 Leukocytes (x 109/L) 2.0 to 2.9 40 20 38 23 45 26 35 1.5 to 1.9 4 1 9 2 5 3 8 1.0 to 1.4 0.9 0 2 0 0 0 0 < 1.0 0 0 0 0 0 0 0 Neutrophils (x 109/L) 1.0 to 1.49 30 32 31 44 42 34 37 0.75 to 0.99 14 15 14 11 16 18 15 0.5 to 0.74 9 9 14 7 8 4 16 < 0.5 11 8 11 5 5 8 3 Platelets (x 109/L) 70 to 99 9 11 11 14 6 12 0.8 50 to 69 2 3 2 3 0 5 2 30 to 49 0 0.4 0 0.4 0 0 0 < 30 0.9 0 1 0.9 0 0 0 Total Bilirubin (mg/dL) 1.5 to 3.0 27 13 32 13 21 7 2 3.1 to 6.0 0.9 0.4 2 0 3 0 0 6.1 to 12.0 0 0 0.4 0 0 0 0 > 12.0 0 0 0 0 0 0 0 Postmarketing Experiences The following adverse reactions have been identified and reported during post approval use of REBETOL in combination with INTRON A or PegIntron. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Blood and Lymphatic System Disorders Pure red cell aplasia, aplastic anemia Ear and Labyrinth Disorders Hearing disorder, vertigo Respiratory, Thoracic and Mediastinal Disorders Pulmonary hypertension Eye Disorders Serous retinal detachment Endocrine Disorders Diabetes DRUG INTERACTIONS Didanosine Exposure to didanosine or its active metabolite (dideoxyadenosine 5'-triphosphate) is increased when didanosine is coadministered with ribavirin, which could cause or worsen clinical toxicities; therefore, coadministration of REBETOL capsules or oral solution and didanosine is contraindicated. Reports of fatal hepatic failure, as well as peripheral neuropathy, pancreatitis, and symptomatic hyperlactatemia/lactic acidosis have been reported in clinical trials. Nucleoside Analogues Hepatic decompensation (some fatal) has occurred in cirrhotic HIV/HCV co-infected patients receiving combination antiretroviral therapy for HIV and interferon alpha and ribavirin. Adding treatment with alpha interferons alone or in combination with ribavirin may increase the risk in this patient population. Patients receiving interferon with ribavirin and nucleoside reverse transcriptase inhibitors (NRTIs) should be closely monitored for treatmentassociated toxicities, especially hepatic decompensation and anemia. Discontinuation of NRTIs should be considered as medically appropriate (see labeling for individual NRTI product). Dose reduction or discontinuation of interferon, ribavirin, or both should also be considered if worsening clinical toxicities are observed, including hepatic decompensation (e.g., Child-Pugh greater than 6). Ribavirin may antagonize the cell culture antiviral activity of stavudine and zidovudine against HIV. Ribavirin has been shown in cell culture to inhibit phosphorylation of lamivudine, stavudine, and zidovudine, which could lead to decreased antiretroviral activity. However, in a study with another pegylated interferon in combination with ribavirin, no pharmacokinetic (e.g., plasma concentrations or intracellular triphosphorylated active metabolite concentrations) or pharmacodynamic (e.g., loss of HIV/HCV virologic suppress) interaction was observed when ribavirin and lamivudine (n=18), stavudine (n=10), or zidovudine (n=6) were coadministered as part of a multidrug regimen in HIV/HCV co-infected subjects. Therefore, concomitant use of ribavirin with either of these drugs should be used with caution. Drugs Metabolized By Cytochrome P-450 Results of in vitro studies using both human and rat liver microsome preparations indicated little or no cytochrome P-450 enzyme-mediated metabolism of ribavirin, with minimal potential for P-450 enzyme-based drug interactions. No pharmacokinetic interactions were noted between INTRON A and REBETOL capsules in a multiple-dose pharmacokinetic study. Azathioprine The use of ribavirin for the treatment of chronic hepatitis C in patients receiving azathioprine has been reported to induce severe pancytopenia and may increase the risk of azathioprine-related myelotoxicity. Inosine monophosphate dehydrogenase (IMDH) is required for one of the metabolic pathways of azathioprine. Ribavirin is known to inhibit IMDH, thereby leading to accumulation of an azathioprine metabolite, 6-methylthioinosine monophosphate (6-MTITP), which is associated with myelotoxicity (neutropenia, thrombocytopenia, and anemia). Patients receiving azathioprine with ribavirin should have complete blood counts, including platelet counts, monitored weekly for the first month, twice monthly for the second and third months of treatment, then monthly or more frequently if dosage or other therapy changes are necessary [see WARNINGS AND PRECAUTIONS].

SIDE EFFECTS PEGASYS in combination with COPEGUS causes a broad variety of serious adverse reactions [see BOXED WARNING and WARNINGS AND PRECAUTIONS]. The most common serious or life-threatening adverse reactions induced or aggravated by COPEGUS/PEGASYS include depression, suicide, relapse of drug abuse/overdose, and bacterial infections each occurring at a frequency of less than 1%. Hepatic decompensation occurred in 2% (10/574) CHC/HIV patients [see WARNINGS AND PRECAUTIONS]. Clinical Studies Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Adult Patients In the pivotal registration trials NV15801 and NV15942, 886 patients received COPEGUS for 48 weeks at doses of 1000/1200 mg based on body weight. In these trials, one or more serious adverse reactions occurred in 10% of CHC monoinfected subjects and in 19% of CHC/HIV subjects receiving PEGASYS alone or in combination with COPEGUS. The most common serious adverse event (3% in CHC and 5% in CHC/HIV) was bacterial infection (e.g., sepsis, osteomyelitis, endocarditis, pyelonephritis, pneumonia). Other serious adverse reactions occurred at a frequency of less than 1% and included: suicide, suicidal ideation, psychosis, aggression, anxiety, drug abuse and drug overdose, angina, hepatic dysfunction, fatty liver, cholangitis, arrhythmia, diabetes mellitus, autoimmune phenomena (e.g., hyperthyroidism, hypothyroidism, sarcoidosis, systemic lupus erythematosus, rheumatoid arthritis), peripheral neuropathy, aplastic anemia, peptic ulcer, gastrointestinal bleeding, pancreatitis, colitis, corneal ulcer, pulmonary embolism, coma, myositis, cerebral hemorrhage, thrombotic thrombocytopenic purpura, psychotic disorder, and hallucination. The percentage of patients in clinical trials who experienced one or more adverse events was 98%. The most commonly reported adverse reactions were psychiatric reactions, including depression, insomnia, irritability, anxiety, and flu-like symptoms such as fatigue, pyrexia, myalgia, headache and rigors. Other common reactions were anorexia, nausea and vomiting, diarrhea, arthralgias, injection site reactions, alopecia, and pruritus. Table 5 shows rates of adverse events occurring in greater than or equal to 5% of subjects receiving pegylated interferon and ribavirin combination therapy in the CHC Clinical Trial, NV15801. Ten percent of CHC monoinfected patients receiving 48 weeks of therapy with PEGASYS in combination with COPEGUS discontinued therapy; 16% of CHC/HIV coinfected patients discontinued therapy. The most common reasons for discontinuation of therapy were psychiatric, flu-like syndrome (e.g., lethargy, fatigue, headache), dermatologic and gastrointestinal disorders, and laboratory abnormalities (thrombocytopenia, neutropenia, and anemia). Overall 39% of patients with CHC or CHC/HIV required modification of PEGASYS and/or COPEGUS therapy. The most common reason for dose modification of PEGASYS in CHC and CHC/HIV patients was for laboratory abnormalities; neutropenia (20% and 27%, respectively) and thrombocytopenia (4% and 6%, respectively). The most common reason for dose modification of COPEGUS in CHC and CHC/HIV patients was anemia (22% and 16%, respectively). PEGASYS dose was reduced in 12% of patients receiving 1000 mg to 1200 mg COPEGUS for 48 weeks and in 7% of patients receiving 800 mg COPEGUS for 24 weeks. COPEGUS dose was reduced in 21% of patients receiving 1000 mg to 1200 mg COPEGUS for 48 weeks and in 12% of patients receiving 800 mg COPEGUS for 24 weeks. Chronic hepatitis C monoinfected patients treated for 24 weeks with PEGASYS and 800 mg COPEGUS were observed to have lower incidence of serious adverse events (3% vs. 10%), hemoglobin less than 10 g/dL (3% vs. 15%), dose modification of PEGASYS (30% vs. 36%) and COPEGUS (19% vs. 38%), and of withdrawal from treatment (5% vs. 15%) compared to patients treated for 48 weeks with PEGASYS and 1000 mg or 1200 mg COPEGUS. On the other hand, the overall incidence of adverse events appeared to be similar in the two treatment groups. Table 5 : Adverse Reactions Occurring in greater than or equal to 5% of Patients in Chronic Hepatitis C Clinical Trials (Study NV15801) Body System CHC Combination Therapy Study NV15801 PEGASYS 180 mcg + 1000 mg or 1200 mg COPEGUS 48 weeks N=451 % Intron A + 1000 mg or 1200 mg Rebetol® 48 weeks N =443 % Application Site Disorders Injection site reaction 23 16 Endocrine Disorders Hypothyroidism 4 5 Flu-like Symptoms and Signs Fatigue/Asthenia 65 68 Pyrexia 41 55 Rigors 25 37 Pain 10 9 Gastrointestinal Nausea/Vomiting 25 29 Diarrhea 11 10 Abdominal pain 8 9 Dry mouth 4 7 Dyspepsia 6 5 Hematologic* Lymphopenia 14 12 Anemia 11 11 Neutropenia 27 8 Thrombocytopenia 5 < 1 Metabolic and Nutritional Anorexia 24 26 Weight decrease 10 10 Musculoskeletal, Connective Tissue and Bone Myalgia 40 49 Arthralgia 22 23 Back pain 5 5 Neurological Headache 43 49 Dizziness (excluding vertigo) 14 14 Memory impairment 6 5 Psychiatric Irritability/Anxiety/Nervousness 33 38 Insomnia 30 37 Depression 20 28 Concentration impairment 10 13 Mood alteration 5 6 Resistance Mechanism Disorders Overall 12 10 Respiratory, Thoracic and Mediastinal Dyspnea 13 14 Cough 10 7 Dyspnea exertional 4 7 Skin and Subcutaneous Tissue Alopecia 28 33 Pruritus 19 18 Dermatitis 16 13 Dry skin 10 13 Rash 8 5 Sweating increased 6 5 Eczema 5 4 Visual Disorders Vision blurred 5 2 * Severe hematologic abnormalities (lymphocyte less than 500 cells/mm³; hemoglobin less than 10 g/dL; neutrophil less than 750 cells/mm³; platelet less than 50,000 cells/mm³). Pediatric Patients In a clinical trial with 114 pediatric subjects (5 to 17 years of age) treated with PEGASYS alone or in combination with COPEGUS, dose modifications were required in approximately one-third of subjects, most commonly for neutropenia and anemia. In general, the safety profile observed in pediatric subjects was similar to that seen in adults. In the pediatric study, the most common adverse events in subjects treated with combination therapy PEGASYS and COPEGUS for up to 48 weeks were influenza-like illness (91%), upper respiratory tract infection (60%), headache (64%), gastrointestinal disorder (56%), skin disorder (47%), and injection-site reaction (45%). Seven subjects receiving combination PEGASYS and COPEGUS treatment for 48 weeks discontinued therapy for safety reasons (depression, psychiatric evaluation abnormal, transient blindness, retinal exudates, hyperglycemia, type 1 diabetes mellitus, and anemia). Severe adverse events were reported in 2 subjects in the PEGASYS plus COPEGUS combination therapy group (hyperglycemia and cholecystectomy). Table 6 : Percentage of Pediatric Subjects with Adverse Reactions* During First 24 Weeks of Treatment by Treatment Group and for 24 Weeks Post-treatment (in at Least 10% of Subjects) System Organ Class Study NV17424 PEGASYS 180 mcg/1.73 m² x BSA + COPEGUS 15 mg/kg (N=55)% PEGASYS 180 mcg/1.73 m² x BSA + Placebo** (N=59)% General disorders and administration site conditions Influenza like illness 91 81 Injection site reaction 44 42 Fatigue 25 20 Irritability 24 14 Gastrointestinal disorders Gastrointestinal disorder 49 44 Nervous system disorders Headache 51 39 Skin and subcutaneous tissue disorders Rash 15 10 Pruritus 11 12 Musculoskeletal, connective tissue and bone disorders Musculoskeletal pain 35 29 Psychiatric disorders Insomnia 9 12 Metabolism and nutrition disorders Decreased appetite 11 14 * Displayed adverse drug reactions include all grades of reported adverse clinical events considered possibly, probably, or definitely related to study drug. **Subjects in the PEGASYS plus placebo arm who did not achieve undetectable viral load at week 24 switched to combination treatment thereafter. Therefore, only the first 24 weeks are presented for the comparison of combination therapy with monotherapy. In pediatric subjects randomized to combination therapy, the incidence of most adverse reactions was similar for the entire treatment period (up to 48 weeks plus 24 weeks follow-up) in comparison to the first 24 weeks, and increased only slightly for headache, gastrointestinal disorder, irritability and rash. The majority of adverse reactions occurred in the first 24 weeks of treatment. Growth Inhibition in Pediatric Subjects [see WARNINGS AND PRECAUTIONS]. Pediatric subjects treated with PEGASYS plus ribavirin combination therapy showed a delay in weight and height increases with up to 48 weeks of therapy compared with baseline. Both weight for age and height for age z-scores as well as the percentiles of the normative population for subject weight and height decreased during treatment. At the end of 2 years follow-up after treatment, most subjects had returned to baseline normative curve percentiles for weight (64th mean percentile at baseline, 60th mean percentile at 2 years post-treatment) and height (54th mean percentile at baseline, 56th mean percentile at 2 years post-treatment). At the end of treatment, 43% (23 of 53) of subjects experienced a weight percentile decrease of more than 15 percentiles, and 25% (13 of 53) experienced a height percentile decrease of more than 15 percentiles on the normative growth curves. At 2 years post-treatment, 16% (6 of 38) of subjects were more than 15 percentiles below their baseline weight curve and 11% (4 of 38) were more than 15 percentiles below their baseline height curve. Thirty-eight of the 114 subjects enrolled in the long-term follow-up study, extending up to 6 years posttreatment. For most subjects, post-treatment recovery in growth at 2 years post-treatment was maintained to 6 years post-treatment. Common Adverse Reactions in CHC with HIV Coinfection (Adults) The adverse event profile of coinfected patients treated with PEGASYS/COPEGUS in Study NR15961 was generally similar to that shown for monoinfected patients in Study NV15801 (Table 5). Events occurring more frequently in coinfected patients were neutropenia (40%), anemia (14%), thrombocytopenia (8%), weight decrease (16%), and mood alteration (9%). Laboratory Test Abnormalities Adult Patients Anemia due to hemolysis is the most significant toxicity of ribavirin therapy. Anemia (hemoglobin less than 10 g/dL) was observed in 13% of all COPEGUS and PEGASYS combination-treated patients in clinical trials. The maximum drop in hemoglobin occurred during the first 8 weeks of initiation of ribavirin therapy [see DOSAGE AND ADMINISTRATION]. Table 7 : Selected Laboratory Abnormalities During Treatment with COPEGUS in Combination With Either PEGASYS or Intron A Laboratory Parameter PEGASYS + Ribavirin 1000/1200 mg 48 wks (N=887) Intron A + Ribavirin 1000/1200 mg 48 wks (N=443) Neutrophils (cells/mm³) 1,000 < 1,500 34% 38% 500 < 1,000 49% 21% < 500 5% 1% Platelets (cells/mm³) 50,000 - < 75,000 11% 4% 20,000 - < 50,000 5% < 1% < 20,000 0 0 Hemoglobin (g/dL) 8.5 -9.9 11% 11% < 8.5 2% < 1% Pediatric Patients Decreases in hemoglobin, neutrophils and platelets may require dose reduction or permanent discontinuation from treatment [see DOSAGE AND ADMINISTRATION]. Most laboratory abnormalities noted during the clinical trial returned to baseline levels shortly after discontinuation of treatment. Table 8 : Selected Hematologic Abnormalities During First 24 Weeks of Treatment by Treatment Group in Previously Untreated Pediatric Subjects Laboratory Parameter PEGASYS 180 mcg/1.73 m² x BSA + COPEGUS 15 mg/kg (N=55) PEGASYS 180 mcg/1.73 m² x BSA + Placebo* (N=59) Neutrophils (cells/mm³) 1,000 - < 1,500 31% 39% 750 - < 1,000 27% 17% 500 - < 750 25% 15% < 500 7% 5% Platelets (cells/mm³) 75,000 - < 100,000 4% 2% 50,000 - < 75,000 0% 2% < 50,000 0% 0% Hemoglobin (g/dL) 8.5 - < 10 7% 3% < 8.5 0% 0% * Subjects in the PEGASYS plus placebo arm who did not achieve undetectable viral load at week 24 switched to combination treatment thereafter. Therefore, only the first 24 weeks are presented for the comparison of combination therapy with monotherapy. In patients randomized to combination therapy, the incidence of abnormalities during the entire treatment phase (up to 48 weeks plus 24 weeks follow-up) in comparison to the first 24 weeks increased slightly for neutrophils between 500 and 1,000 cells/mm³ and hemoglobin values between 8.5 and 10 g/dL. The majority of hematologic abnormalities occurred in the first 24 weeks of treatment. Postmarketing Experience The following adverse reactions have been identified and reported during post-approval use of PEGASYS/COPEGUS combination therapy. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Blood and Lymphatic System Disorders Pure red cell aplasia Ear and Labyrinth Disorders Hearing impairment, hearing loss Eye Disorders Serous retinal detachment Immune Disorders Liver and renal graft rejection Metabolism and Nutrition Disorders Dehydration Skin and Subcutaneous Tissue Disorders Stevens-Johnson Syndrome (SJS) Toxic epidermal necrolysis (TEN) DRUG INTERACTIONS Results from a pharmacokinetic sub-study demonstrated no pharmacokinetic interaction between PEGASYS (peginterferon alfa-2a) and ribavirin. Nucleoside Reverse Transcriptase Inhibitors (NRTIs) In vitro data indicate ribavirin reduces phosphorylation of lamivudine, stavudine, and zidovudine. However, no pharmacokinetic (e.g., plasma concentrations or intracellular triphosphorylated active metabolite concentrations) or pharmacodynamic (e.g., loss of HIV/HCV virologic suppression) interaction was observed when ribavirin and lamivudine (n=18), stavudine (n=10), or zidovudine (n=6) were co-administered as part of a multi-drug regimen to HCV/HIV coinfected patients. In Study NR15961 among the CHC/HIV coinfected cirrhotic patients receiving NRTIs, cases of hepatic decompensation (some fatal) were observed [see WARNINGS AND PRECAUTIONS]. Patients receiving PEGASYS/COPEGUS and NRTIs should be closely monitored for treatment-associated toxicities. Physicians should refer to prescribing information for the respective NRTIs for guidance regarding toxicity management. In addition, dose reduction or discontinuation of PEGASYS, COPEGUS or both should also be considered if worsening toxicities are observed, including hepatic decompensation (e.g., Child-Pugh greater than or equal to 6) [see WARNINGS AND PRECAUTIONS and DOSAGE AND ADMINISTRATION]. Didanosine Co-administration of COPEGUS and didanosine is contraindicated. Didanosine or its active metabolite (dideoxyadenosine 5'-triphosphate) concentrations are increased when didanosine is co-administered with ribavirin, which could cause or worsen clinical toxicities. Reports of fatal hepatic failure as well as peripheral neuropathy, pancreatitis, and symptomatic hyperlactatemia/lactic acidosis have been reported in clinical trials [see CONTRAINDICATIONS]. Zidovudine In Study NR15961, patients who were administered zidovudine in combination with PEGASYS/COPEGUS developed severe neutropenia (ANC less than 500) and severe anemia (hemoglobin less than 8 g/dL) more frequently than similar patients not receiving zidovudine (neutropenia 15% vs. 9%) (anemia 5% vs. 1%). Discontinuation of zidovudine should be considered as medically appropriate. Drugs Metabolized By Cytochrome P450 In vitro studies indicate that ribavirin does not inhibit CYP 2C9, CYP 2C19, CYP 2D6 or CYP 3A4. Azathioprine The use of ribavirin to treat chronic hepatitis C in patients receiving azathioprine has been reported to induce severe pancytopenia and may increase the risk of azathioprine-related myelotoxicity. Inosine monophosphate dehydrogenase (IMDH) is required for one of the metabolic pathways of azathioprine. Ribavirin is known to inhibit IMDH, thereby leading to accumulation of an azathioprine metabolite, 6-methylthioinosine monophosphate (6-MTITP), which is associated with myelotoxicity (neutropenia, thrombocytopenia, and anemia). Patients receiving azathioprine with ribavirin should have complete blood counts, including platelet counts, monitored weekly for the first month, twice monthly for the second and third months of treatment, then monthly or more frequently if dosage or other therapy changes are necessary [see WARNINGS AND PRECAUTIONS].

WARNINGS SUDDEN DETERIORATION OF RESPIRATORY FUNCTION HAS BEEN ASSOCIATED WITH INITIATION OF AEROSOLIZED VIRAZOLE (ribavirin) USE IN INFANTS. Respiratory function should be carefully monitored during treatment. If initiation of aerosolized VIRAZOLE (ribavirin) treatment appears to produce sudden deterioration of respiratory function, treatment should be stopped and reinstituted only with extreme caution, continuous monitoring, and consideration of concomitant administration of bronchodilators. Use with Mechanical Ventilators USE OF AEROSOLIZED VIRAZOLE (ribavirin) IN PATIENTS REQUIRING MECHANICAL VENTILATOR ASSISTANCE SHOULD BE UNDERTAKEN ONLY BY PHYSICIANS AND SUPPORT STAFF FAMILIAR WITH THIS MODE OF ADMINISTRATION AND THE SPECIFIC VENTILATOR BEING USED. Strict attention must be paid to procedures that have been shown to minimize the accumulation of drug precipitate, which can result in mechanical ventilator dysfunction and associated increased pulmonary pressures. These procedures include the use of bacteria filters in series in the expiratory limb of the ventilator circuit with frequent changes (every 4 hours), water column pressure release valves to indicate elevated ventilator pressures, frequent monitoring of these devices and verification that ribavirin crystals have not accumulated within the ventilator circuitry, and frequent suctioning and monitoring of the patient (see Clinical Studies). Those administering aerosolized VIRAZOLE (ribavirin) in conjunction with mechanical ventilator use should be thoroughly familiar with detailed descriptions of these procedures as outlined in the SPAG-2 manual. PRECAUTIONS General Patients with severe lower respiratory tract infection due to respiratory syncytial virus require optimum monitoring and attention to respiratory and fluid status (see SPAG-2 manual). Carcinogenesis and Mutagenesis Ribavirin increased the incidence of cell transformations and mutations in mouse Balb/c 3T3 (fibroblasts) and L5178Y (lymphoma) cells at concentrations of 0.015 and 0.03-5.0 mg/mL, respectively (without metabolic activation). Modest increases in mutation rates (3-4x) were observed at concentrations between 3.75-10.0 mg/mL in L5178Y cells in vitro with the addition of a metabolic activation fraction. In the mouse micronucleus assay, ribavirin was clastogenic at intravenous doses of 20-200 mg/kg, (estimated human equivalent of 1.67-16.7 mg/kg, based on body surface area adjustment for a 60 kg adult). Ribavirin was not mutagenic in a dominant lethal assay in rats at intraperitoneal doses between 50-200 mg/kg when administered for 5 days (estimated human equivalent of 7.14-28.6 mg/kg, based on body surface area adjustment; see Pharmacokinetics). In vivo carcinogenicity studies with ribavirin are incomplete. However, results of a chronic feeding study with ribavirin in rats, at doses of 16-100 mg/kg/day (estimated human equivalent of 2.3-14.3 mg/kg/day, based on body surface area adjustment for the adult), suggest that ribavirin may induce benign mammary, pancreatic, pituitary and adrenal tumors. Preliminary results of 2 oral gavage oncogenicity studies in the mouse and rat (18-24 months; doses of 20-75 and 10-40 mg/kg/day, respectively [estimated human equivalent of 1.67-6.25 and 1.43-5.71 mg/kg/day, respectively, based on body surface area adjustment for the adult]) are inconclusive as to the carcinogenic potential of ribavirin (see Pharmacokinetics). However, these studies have demonstrated a relationship between chronic ribavirin exposure and increased incidences of vascular lesions (microscopic hemorrhages in mice) and retinal degeneration (in rats). Impairment of Fertility The fertility of ribavirin-treated animals (male or female) has not been fully investigated. However, in the mouse, administration of ribavirin at doses between 35-150 mg/kg/day (estimated human equivalent of 2.92-12.5 mg/kg/day, based on body surface area adjustment for the adult) resulted in significant seminiferous tubule atrophy, decreased sperm concentrations, and increased numbers of sperm with abnormal morphology. Partial recovery of sperm production was apparent 3-6 months following dose cessation. In several additional toxicology studies, ribavirin has been shown to cause testicular lesions (tubular atrophy) in adult rats at oral dose levels as low as 16 mg/kg/day (estimated human equivalent of 2.29 mg/kg/day, based on body surface area adjustment; see Pharmacokinetics). Lower doses were not tested. The reproductive capacity of treated male animals has not been studied Pregnancy: Category X Ribavirin has demonstrated significant teratogenic and/or embryocidal potential in all animal species in which adequate studies have been conducted. Teratogenic effects were evident after single oral doses of 2.5 mg/kg or greater in the hamster, and after daily oral doses of 0.3 and 1.0 mg/kg in the rabbit and rat, respectively (estimated human equivalent doses of 0.12 and 0.14 mg/kg, based on body surface area adjustment for the adult). Malformations of the skull, palate, eye, jaw, limbs, skeleton, and gastrointestinal tract were noted. The incidence and severity of teratogenic effects increased with escalation of the drug dose. Survival of fetuses and offspring was reduced. Ribavirin caused embryo lethality in the rabbit at daily oral dose levels as low as 1 mg/kg. No teratogenic effects were evident in the rabbit and rat administered daily oral doses of 0.1 and 0.3 mg/kg, respectively with estimated human equivalent doses of 0.01 and 0.04 mg/kg, based on body surface area adjustment (see Pharmacokinetics). These doses are considered to define the "No Observable Teratogenic Effects Level" (NOTEL) for ribavirin in the rabbit and rat. Following oral administration of ribavirin in the pregnant rat (1.0 mg/kg) and rabbit (0.3 mg/kg), mean plasma levels of drug ranged from 0.104.20 µM[0.024-0.049 u/mL] at 1 hour after dosing, to undetectable levels at 24 hours. At 1 hour following the administration of 0.3 or 0.1 mg/kg in the rat and rabbit (NOTEL), respectively, mean plasma levels of drug in both species were near or below the limit of detection (0.05 µM; see Pharmacokinetics). Although clinical studies have not been performed, VIRAZOLE (ribavirin) may cause fetal harm in humans. As noted previously, ribavirin is concentrated in red blood cells and persists for the life of the cell. Thus the terminal half-life for the systemic elimination of ribavirin is essentially that of the half-life of circulating erythrocytes. The minimum interval following exposure to VIRAZOLE (ribavirin) before pregnancy may be safely initiated is unknown (see CONTRAINDICATIONS, WARNINGS, and Information for Health Care Personnel). Nursing Mothers VIRAZOLE (ribavirin) has been shown to be toxic to lactating animals and their offspring. It is not known if VIRAZOLE (ribavirin) is excreted in human milk. Information for Health Care Personnel Health care workers directly providing care to patients receiving aerosolized VIRAZOLE should be aware that ribavirin has been shown to be teratogenic in all animal species in which adequate studies have been conducted (rodents and rabbits). Although no reports of teratogenesis in offspring of mothers who were exposed to aerosolized VIRAZOLE (ribavirin) during pregnancy have been confirmed, no controlled studies have been conducted in pregnant women. Studies of environmental exposure in treatment settings have shown that the drug can disperse into the immediate bedside area during routine patient care activities with highest ambient levels closest to the patient and extremely low levels outside of the immediate bedside area. Adverse reactions resulting from actual occupational exposure in adults are described below (see Adverse Events in Health Care Workers). Some studies have documented ambient drug concentrations at the bedside that could potentially lead to systemic exposures above those considered safe for exposure during pregnancy (1/1000 of the NOTEL dose in the most sensitive animal species).7,8,9 A1992 study conducted by the National Institute of Occupational Safety and Health (NIOSH) demonstrated measurable urine levels of ribavirin in health care workers exposed to aerosol in the course of direct patient care.7 Levels were lowest in workers caring for infants receiving aerosolized VIRAZOLE (ribavirin) with mechanical ventilation and highest in those caring for patients being administered the drug via an oxygen tent or hood. This study employed a more sensitive assay to evaluate ribavirin levels in urine than was available for several previous studies of environmental exposure that failed to detect measurable ribavirin levels in exposed workers. Creatinine adjusted urine levels in the NIOSH study ranged from less than 0.001 to 0.140 µM of ribavirin per gram of creatinine in exposed workers. However, the relationship between urinary ribavirin levels in exposed workers, plasma levels in animal studies, and the specific risk of teratogenesis in exposed pregnant women is unknown. It is good practice to avoid unnecessary occupational exposure to chemicals wherever possible. Hospitals are encouraged to conduct training programs to minimize potential occupational exposure to VIRAZOLE (ribavirin) . Health care workers who are pregnant should consider avoiding direct care of patients receiving aerosolized VIRAZOLE (ribavirin) . If close patient contact cannot be avoided, precautions to limit exposure should be taken. These include administration of VIRAZOLE (ribavirin) in negative pressure rooms; adequate room ventilation (at least six air exchanges per hour); the use of VIRAZOLE (ribavirin) aerosol scavenging devices; turning off the SPAG-2 device for 5 to 10 minutes prior to prolonged patient contact; and wearing appropriately fitted respirator masks. Surgical masks do not provide adequate filtration of VIRAZOLE (ribavirin) particles. Further information is available from NIOSH's Hazard Evaluation and Technical Assistance Branch and additional recommendations have been published in an Aerosol Consensus Statement by the American Respiratory Care Foundation and the American Association for Respiratory Care10 REFERENCES 7. Decker, John, Shultz, Ruth A., Health Hazaid Evaluation Report: Florida Hospital, Orlando, Florida. Cincinnati OH: U.S. Department of Health and Human Services, Public Health Service, Centers for NIOSH Report No. HETA 91 -104-2229.* 8. Barnes, D.J. and Doursew, M. Reference dose: Description and use in health risk assessments. Regul Tox. and Pharm. Vol. 8; p. 471-486, 1988. 9. Federal Register Vol. 53 No. 126 Thurs. June 30,1988 p. 2483424847. 10. American Association for Respiratory Care [1991]. Aerosol Consensus Statement-1991. Respiratory Care 36(9): 916-921.

WARNINGS Included as part of the PRECAUTIONS section. PRECAUTIONS Pregnancy REBETOL capsules and oral solution may cause birth defects and death of the unborn child. REBETOL therapy should not be started until a report of a negative pregnancy test has been obtained immediately prior to planned initiation of therapy. Patients should use at least two forms of contraception and have monthly pregnancy tests during treatment and during the 6-month period after treatment has been stopped. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients. REBETOL has demonstrated significant teratogenic and embryocidal effects in all animal species in which adequate studies have been conducted. These effects occurred at doses as low as one twentieth of the recommended human dose of ribavirin. REBETOL therapy should not be started until a report of a negative pregnancy test has been obtained immediately prior to planned initiation of therapy [see BOXED WARNING, CONTRAINDICATIONS, Use In Specific Populations, and PATIENT INFORMATION]. Anemia The primary toxicity of ribavirin is hemolytic anemia, which was observed in approximately 10% of REBETOL/INTRON A-treated subjects in clinical trials. The anemia associated with REBETOL capsules occurs within 1 to 2 weeks of initiation of therapy. Because the initial drop in hemoglobin may be significant, it is advised that hemoglobin or hematocrit be obtained before the start of treatment and at Week 2 and Week 4 of therapy, or more frequently if clinically indicated. Patients should then be followed as clinically appropriate [see DOSAGE AND ADMINISTRATION]. Fatal and nonfatal myocardial infarctions have been reported in patients with anemia caused by REBETOL. Patients should be assessed for underlying cardiac disease before initiation of ribavirin therapy. Patients with pre-existing cardiac disease should have electrocardiograms administered before treatment, and should be appropriately monitored during therapy. If there is any deterioration of cardiovascular status, therapy should be suspended or discontinued [see DOSAGE AND ADMINISTRATION]. Because cardiac disease may be worsened by drug-induced anemia, patients with a history of significant or unstable cardiac disease should not use REBETOL. Pancreatitis REBETOL and INTRON A or PegIntron therapy should be suspended in patients with signs and symptoms of pancreatitis and discontinued in patients with confirmed pancreatitis. Pulmonary Disorders Pulmonary symptoms, including dyspnea, pulmonary infiltrates, pneumonitis, pulmonary hypertension, and pneumonia, have been reported during therapy with REBETOL with alpha interferon combination therapy; occasional cases of fatal pneumonia have occurred. In addition, sarcoidosis or the exacerbation of sarcoidosis has been reported. If there is evidence of pulmonary infiltrates or pulmonary function impairment, the patient should be closely monitored, and if appropriate, combination therapy should be discontinued. Ophthalmologic Disorders Ribavirin is used in combination therapy with alpha interferons. Decrease or loss of vision, retinopathy including macular edema, retinal artery or vein, thrombosis, retinal hemorrhages and cotton wool spots, optic neuritis, papilledema, and serous retinal detachment are induced or aggravated by treatment with alpha interferons. All patients should receive an eye examination at baseline. Patients with pre-existing ophthalmologic disorders (e.g., diabetic or hypertensive retinopathy) should receive periodic ophthalmologic exams during combination therapy with alpha interferon treatment. Any patient who develops ocular symptoms should receive a prompt and complete eye examination. Combination therapy with alpha interferons should be discontinued in patients who develop new or worsening ophthalmologic disorders. Laboratory Tests PegIntron in combination with ribavirin may cause severe decreases in neutrophil and platelet counts, and hematologic, endocrine (e.g., TSH), and hepatic abnormalities. Patients on PegIntron/REBETOL combination therapy should have hematology and blood chemistry testing before the start of treatment and then periodically thereafter. In the adult clinical trial, complete blood counts (including hemoglobin, neutrophil, and platelet counts) and chemistries (including AST, ALT, bilirubin, and uric acid) were measured during the treatment period at Weeks 2, 4, 8, 12, and then at 6-week intervals, or more frequently if abnormalities developed. In pediatric subjects, the same laboratory parameters were evaluated with additional assessment of hemoglobin at treatment Week 6. TSH levels were measured every 12 weeks during the treatment period. HCV-RNA should be measured periodically during treatment [see DOSAGE AND ADMINISTRATION]. Dental And Periodontal Disorders Dental and periodontal disorders have been reported in patients receiving ribavirin and interferon or peginterferon combination therapy. In addition, dry mouth could have a damaging effect on teeth and mucous membranes of the mouth during long-term treatment with the combination of REBETOL and pegylated or nonpegylated interferon alfa-2b. Patients should brush their teeth thoroughly twice daily and have regular dental examinations. If vomiting occurs, they should be advised to rinse out their mouth thoroughly afterwards. Concomitant Administration Of Azathioprine Pancytopenia (marked decreases in red blood cells, neutrophils, and platelets) and bone marrow suppression have been reported in the literature to occur within 3 to 7 weeks after the concomitant administration of pegylated interferon/ribavirin and azathioprine. In this limited number of patients (n=8), myelotoxicity was reversible within 4 to 6 weeks upon withdrawal of both HCV antiviral therapy and concomitant azathioprine and did not recur upon reintroduction of either treatment alone. PegIntron, REBETOL, and azathioprine should be discontinued for pancytopenia, and pegylated interferon/ribavirin should not be reintroduced with concomitant azathioprine [see DRUG INTERACTIONS]. Impact On Growth - Pediatric Use Data on the effects of PegIntron and REBETOL on growth come from an open-label study in subjects 3 through 17 years of age, in which weight and height changes are compared to US normative population data. In general, the weight and height gain of pediatric subjects treated with PegIntron and REBETOL lags behind that predicted by normative population data for the entire length of treatment. Severely inhibited growth velocity (less than 3rd percentile) was observed in 70% of the subjects while on treatment. Following treatment, rebound growth and weight gain occurred in most subjects. Long-term follow-up data in pediatric subjects, however, indicates that PegIntron in combination therapy with REBETOL may induce a growth inhibition that results in reduced adult height in some patients [see ADVERSE REACTIONS]. Similarly, an impact on growth was seen in subjects after treatment with REBETOL and INTRON A combination therapy for one year. In a long-term follow-up trial of a limited number of these subjects, combination therapy resulted in reduced final adult height in some subjects [see ADVERSE REACTIONS]. Usage Safeguards Based on results of clinical trials, ribavirin monotherapy is not effective for the treatment of chronic hepatitis C virus infection; therefore, REBETOL capsules or oral solution must not be used alone. The safety and efficacy of REBETOL capsules and oral solution have only been established when used together with INTRON A or PegIntron (not other interferons) as combination therapy. The safety and efficacy of REBETOL/INTRON A and PegIntron therapy for the treatment of HIV infection, adenovirus, RSV, parainfluenza, or influenza infections have not been established. REBETOL capsules should not be used for these indications. Ribavirin for inhalation has separate labeling, which should be consulted if ribavirin inhalation therapy is being considered. There are significant adverse reactions caused by REBETOL/INTRON A or PegIntron therapy, including severe depression and suicidal ideation, hemolytic anemia, suppression of bone marrow function, autoimmune and infectious disorders, pulmonary dysfunction, pancreatitis, and diabetes. Suicidal ideation or attempts occurred more frequently among pediatric patients, primarily adolescents, compared to adult patients (2.4% versus 1%) during treatment and off-therapy follow-up. Labeling for INTRON A and PegIntron should be reviewed in their entirety for additional safety information prior to initiation of combination treatment. Patient Counseling Information Advise the patient to read the FDA-Approved Patient Labeling (Medication Guide). Anemia The most common adverse experience occurring with REBETOL capsules is anemia, which may be severe [see WARNINGS AND PRECAUTIONS and ADVERSE REACTIONS]. Patients should be advised that laboratory evaluations are required prior to starting therapy and periodically thereafter [see DOSAGE AND ADMINISTRATION]. It is advised that patients be well hydrated, especially during the initial stages of treatment. Pregnancy Patients must be informed that REBETOL capsules and oral solution may cause birth defects and death of the unborn child. REBETOL must not be used by women who are pregnant or by men whose female partners are pregnant. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients taking REBETOL. REBETOL should not be initiated until a report of a negative pregnancy test has been obtained immediately prior to initiation of therapy. Patients must perform a pregnancy test monthly during therapy and for 6 months post therapy. Women of childbearing potential must be counseled about use of effective contraception (two reliable forms) prior to initiating therapy. Patients (male and female) must be advised of the teratogenic/embryocidal risks and must be instructed to practice effective contraception during REBETOL and for 6 months post therapy. Patients (male and female) should be advised to notify the physician immediately in the event of a pregnancy [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS, and Use in Specific Populations]. If pregnancy does occur during treatment or during 6 months post therapy, the patient must be advised of the teratogenic risk of REBETOL therapy to the fetus. Patients, or partners of patients, should immediately report any pregnancy that occurs during treatment or within 6 months after treatment cessation to their physician. Prescribers should report such cases by calling 1-800-593-2214. Risks Versus Benefits Patients receiving REBETOL capsules should be informed of the benefits and risks associated with treatment, directed in its appropriate use, and referred to the patient Medication Guide. Patients should be informed that the effect of treatment of hepatitis C infection on transmission is not known, and that appropriate precautions to prevent transmission of the hepatitis C virus should be taken. Patients should be informed about what to do in the event they miss a dose of REBETOL; the missed dose should be taken as soon as possible during the same day. Patients should not double the next dose. Patients should be advised to contact their healthcare provider if they have questions. Nonclinical Toxicology Carcinogenesis, Mutagenesis, Impairment Of Fertility Carcinogenesis Ribavirin did not cause an increase in any tumor type when administered for 6 months in the transgenic p53 deficient mouse model at doses up to 300 mg/kg (estimated human equivalent of 25 mg/kg based on body surface area adjustment for a 60 kg adult; approximately 1.9 times the maximum recommended human daily dose). Ribavirin was noncarcinogenic when administered for 2 years to rats at doses up to 40 mg/kg (estimated human equivalent of 5.71 mg/kg based on body surface area adjustment for a 60 kg adult). Mutagenesis Ribavirin demonstrated increased incidences of mutation and cell transformation in multiple genotoxicity assays. Ribavirin was active in the Balb/3T3 In Vitro Cell Transformation Assay. Mutagenic activity was observed in the mouse lymphoma assay, and at doses of 20 to 200 mg/kg (estimated human equivalent of 1.67 to 16.7 mg/kg, based on body surface area adjustment for a 60 kg adult; 0.1 to 1 times the maximum recommended human 24-hour dose of ribavirin) in a mouse micronucleus assay. A dominant lethal assay in rats was negative, indicating that if mutations occurred in rats they were not transmitted through male gametes. Impairment of Fertility Ribavirin demonstrated significant embryocidal and teratogenic effects at doses well below the recommended human dose in all animal species in which adequate studies have been conducted. Malformations of the skull, palate, eye, jaw, limbs, skeleton, and gastrointestinal tract were noted. The incidence and severity of teratogenic effects increased with escalation of the drug dose. Survival of fetuses and offspring was reduced. In conventional embryotoxicity/teratogenicity studies in rats and rabbits, observed no-effect dose levels were well below those for proposed clinical use (0.3 mg/kg/day for both the rat and rabbit; approximately 0.06 times the recommended human 24-hour dose of ribavirin). No maternal toxicity or effects on offspring were observed in a peri/postnatal toxicity study in rats dosed orally at up to 1 mg/kg/day (estimated human equivalent dose of 0.17 mg/kg based on body surface area adjustment for a 60 kg adult; approximately 0.01 times the maximum recommended human 24-hour dose of ribavirin) [see CONTRAINDICATIONS, and WARNINGS AND PRECAUTIONS]. Fertile women and partners of fertile women should not receive REBETOL unless the patient and his/her partner are using effective contraception (two reliable forms). Based on a multiple-dose half-life (t1/2) of ribavirin of 12 days, effective contraception must be utilized for 6 months post-therapy (e.g., 15 half-lives of clearance for ribavirin). REBETOL should be used with caution in fertile men. In studies in mice to evaluate the time course and reversibility of ribavirin-induced testicular degeneration at doses of 15 to 150 mg/kg/day (estimated human equivalent of 1.25 to 12.5 mg/kg/day, based on body surface area adjustment for a 60- kg adult; 0.1-0.8 times the maximum human 24-hour dose of ribavirin) administered for 3 or 6 months, abnormalities in sperm occurred. Upon cessation of treatment, essentially total recovery from ribavirin-induced testicular toxicity was apparent within 1 or 2 spermatogenesis cycles. Use In Specific Populations Pregnancy Pregnancy Category X [See CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS, and Nonclinical Toxicology]. Treatment and Post-treatment: Potential Risk to the Fetus Ribavirin is known to accumulate in intracellular components from where it is cleared very slowly. It is not known whether ribavirin contained in sperm will exert a potential teratogenic effect upon fertilization of the ova. In a study in rats, it was concluded that dominant lethality was not induced by ribavirin at doses up to 200 mg/kg for 5 days (estimated human equivalent doses of 7.14 to 28.6 mg/kg, based on body surface area adjustment for a 60 kg adult; up to 1.7 times the maximum recommended human dose of ribavirin). However, because of the potential human teratogenic effects of ribavirin, male patients should be advised to take every precaution to avoid risk of pregnancy for their female partners. Women of childbearing potential should not receive REBETOL unless they are using effective contraception (two reliable forms) during the therapy period. In addition, effective contraception should be utilized for 6 months post-therapy based on a multiple-dose half-life (t1/2) of ribavirin of 12 days. Male patients and their female partners must practice effective contraception (two reliable forms) during treatment with REBETOL and for the 6- month post-therapy period (e.g., 15 half-lives for ribavirin clearance from the body). A Ribavirin Pregnancy Registry has been established to monitor maternal-fetal outcomes of pregnancies in female patients and female partners of male patients exposed to ribavirin during treatment and for 6 months following cessation of treatment. Physicians and patients are encouraged to report such cases by calling 1-800-593-2214. Nursing Mothers It is not known whether the REBETOL product is excreted in human milk. Because of the potential for serious adverse reactions from the drug in nursing infants, a decision should be made whether to discontinue nursing or to delay or discontinue REBETOL. Pediatric Use Safety and effectiveness of REBETOL in combination with PegIntron has not been established in pediatric patients below the age of 3 years. For treatment with REBETOL/INTRON A, evidence of disease progression, such as hepatic inflammation and fibrosis, as well as prognostic factors for response, HCV genotype and viral load should be considered when deciding to treat a pediatric patient. The benefits of treatment should be weighed against the safety findings observed. Long-term follow-up data in pediatric subjects indicates that REBETOL in combination with PegIntron or with INTRON A may induce a growth inhibition that results in reduced height in some patients [see WARNINGS AND PRECAUTIONS and ADVERSE REACTIONS]. Suicidal ideation or attempts occurred more frequently among pediatric patients, primarily adolescents, compared to adult patients (2.4% vs. 1%) during treatment and off-therapy follow-up [see WARNINGS AND PRECAUTIONS]. As in adult patients, pediatric patients experienced other psychiatric adverse reactions (e.g., depression, emotional lability, somnolence), anemia, and neutropenia [see WARNINGS AND PRECAUTIONS]. Geriatric Use Clinical trials of REBETOL/INTRON A or PegIntron therapy did not include sufficient numbers of subjects aged 65 and over to determine if they respond differently from younger subjects. REBETOL is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients often have decreased renal function, care should be taken in dose selection. Renal function should be monitored and dosage adjustments should be made accordingly. REBETOL should not be used in patients with creatinine clearance less than 50 mL/min [see CONTRAINDICATIONS]. In general, REBETOL capsules should be administered to elderly patients cautiously, starting at the lower end of the dosing range, reflecting the greater frequency of decreased hepatic and cardiac function, and of concomitant disease or other drug therapy. In clinical trials, elderly subjects had a higher frequency of anemia (67%) than younger patients (28%) [see WARNINGS AND PRECAUTIONS]. Organ Transplant Recipients The safety and efficacy of INTRON A and PegIntron alone or in combination with REBETOL for the treatment of hepatitis C in liver or other organ transplant recipients have not been established. In a small (n=16) single-center, uncontrolled case experience, renal failure in renal allograft recipients receiving interferon alpha and ribavirin combination therapy was more frequent than expected from the center's previous experience with renal allograft recipients not receiving combination therapy. The relationship of the renal failure to renal allograft rejection is not clear. HIV Or HBV Co-infection The safety and efficacy of PegIntron/REBETOL and INTRON A/REBETOL for the treatment of patients with HCV co-infected with HIV or HBV have not been established.

WARNINGS Included as part of the PRECAUTIONS section. PRECAUTIONS Significant adverse reactions associated with COPEGUS/PEGASYS combination therapy include severe depression and suicidal ideation, hemolytic anemia, suppression of bone marrow function, autoimmune and infectious disorders, ophthalmologic disorders, cerebrovascular disorders, pulmonary dysfunction, colitis, pancreatitis, and diabetes. The PEGASYS Package Insert should be reviewed in its entirety for additional safety information prior to initiation of combination treatment. Pregnancy COPEGUS may cause birth defects and/or death of the exposed fetus. Ribavirin has demonstrated significant teratogenic and/or embryocidal effects in all animal species in which adequate studies have been conducted. These effects occurred at doses as low as one twentieth of the recommended human dose of ribavirin. COPEGUS therapy should not be started unless a report of a negative pregnancy test has been obtained immediately prior to planned initiation of therapy. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients. Patients should be instructed to use at least two forms of effective contraception during treatment and for 6 months after treatment has been stopped. Pregnancy testing should occur monthly during COPEGUS therapy and for 6 months after therapy has stopped [see BOXED WARNING, CONTRAINDICATIONS, Use in Specific Populations, and PATIENT INFORMATION]. Anemia The primary toxicity of ribavirin is hemolytic anemia, which was observed in approximately 13% of all COPEGUS/PEGASYS-treated subjects in clinical trials. Anemia associated with COPEGUS occurs within 1 to 2 weeks of initiation of therapy. Because the initial drop in hemoglobin may be significant, it is advised that hemoglobin or hematocrit be obtained pretreatment and at week 2 and week 4 of therapy or more frequently if clinically indicated. Patients should then be followed as clinically appropriate. Caution should be exercised in initiating treatment in any patient with baseline risk of severe anemia (e.g., spherocytosis, history of gastrointestinal bleeding) [see DOSAGE AND ADMINISTRATION]. Fatal and nonfatal myocardial infarctions have been reported in patients with anemia caused by COPEGUS. Patients should be assessed for underlying cardiac disease before initiation of ribavirin therapy. Patients with pre-existing cardiac disease should have electrocardiograms administered before treatment, and should be appropriately monitored during therapy. If there is any deterioration of cardiovascular status, therapy should be suspended or discontinued [see DOSAGE AND ADMINISTRATION]. Because cardiac disease may be worsened by drug-induced anemia, patients with a history of significant or unstable cardiac disease should not use COPEGUS [see BOXED WARNING and DOSAGE AND ADMINISTRATION]. Hepatic Failure Chronic hepatitis C (CHC) patients with cirrhosis may be at risk of hepatic decompensation and death when treated with alpha interferons, including PEGASYS. Cirrhotic CHC patients coinfected with HIV receiving highly active antiretroviral therapy (HAART) and interferon alfa-2a with or without ribavirin appear to be at increased risk for the development of hepatic decompensation compared to patients not receiving HAART. In Study NR15961 [see Clinical Studies], among 129 CHC/HIV cirrhotic patients receiving HAART, 14 (11%) of these patients across all treatment arms developed hepatic decompensation resulting in 6 deaths. All 14 patients were on NRTIs, including stavudine, didanosine, abacavir, zidovudine, and lamivudine. These small numbers of patients do not permit discrimination between specific NRTIs or the associated risk. During treatment, patients' clinical status and hepatic function should be closely monitored for signs and symptoms of hepatic decompensation. Treatment with PEGASYS/COPEGUS should be discontinued immediately in patients with hepatic decompensation [see CONTRAINDICATIONS]. Hypersensitivity Severe acute hypersensitivity reactions (e.g., urticaria, angioedema, bronchoconstriction, and anaphylaxis) have been observed during alpha interferon and ribavirin therapy. If such a reaction occurs, therapy with PEGASYS and COPEGUS should be discontinued immediately and appropriate medical therapy instituted. Serious skin reactions including vesiculobullous eruptions, reactions in the spectrum of Stevens-Johnson Syndrome (erythema multiforme major) with varying degrees of skin and mucosal involvement and exfoliative dermatitis (erythroderma) have been reported in patients receiving PEGASYS with and without ribavirin. Patients developing signs or symptoms of severe skin reactions must discontinue therapy [see ADVERSE REACTIONS]. Pulmonary Disorders Dyspnea, pulmonary infiltrates, pneumonitis, pulmonary hypertension, and pneumonia have been reported during therapy with ribavirin and interferon. Occasional cases of fatal pneumonia have occurred. In addition, sarcoidosis or the exacerbation of sarcoidosis has been reported. If there is evidence of pulmonary infiltrates or pulmonary function impairment, patients should be closely monitored and, if appropriate, combination COPEGUS/PEGASYS treatment should be discontinued. Bone Marrow Suppression Pancytopenia (marked decreases in RBCs, neutrophils and platelets) and bone marrow suppression have been reported in the literature to occur within 3 to 7 weeks after the concomitant administration of pegylated interferon/ribavirin and azathioprine. In this limited number of patients (n=8), myelotoxicity was reversible within 4 to 6 weeks upon withdrawal of both HCV antiviral therapy and concomitant azathioprine and did not recur upon reintroduction of either treatment alone. PEGASYS, COPEGUS, and azathioprine should be discontinued for pancytopenia, and pegylated interferon/ribavirin should not be re-introduced with concomitant azathioprine [see DRUG INTERACTIONS]. Pancreatitis COPEGUS and PEGASYS therapy should be suspended in patients with signs and symptoms of pancreatitis, and discontinued in patients with confirmed pancreatitis. Impact On Growth In Pediatric Patients During combination therapy for up to 48 weeks with PEGASYS plus ribavirin, growth inhibition was observed in pediatric subjects 5 to 17 years of age. Decreases in weight for age z-score and height for age z-score up to 48 weeks of therapy compared with baseline were observed. At 2 years post-treatment, 16% of pediatric subjects were more than 15 percentiles below their baseline weight curve and 11% were more than 15 percentiles below their baseline height curve. The available longer term data on subjects who were followed up to 6 years post-treatment are too limited to determine the risk of reduced adult height in some patients [see Clinical Studies Experience]. Laboratory Tests Before beginning PEGASYS/COPEGUS combination therapy, standard hematological and biochemical laboratory tests are recommended for all patients. Pregnancy screening for women of childbearing potential must be performed. Patients who have pre-existing cardiac abnormalities should have electrocardiograms administered before treatment with PEGASYS/COPEGUS. After initiation of therapy, hematological tests should be performed at 2 weeks and 4 weeks and biochemical tests should be performed at 4 weeks. Additional testing should be performed periodically during therapy. In adult clinical studies, the CBC (including hemoglobin level and white blood cell and platelet counts) and chemistries (including liver function tests and uric acid) were measured at 1, 2, 4, 6, and 8 weeks, and then every 4 to 6 weeks or more frequently if abnormalities were found. In the pediatric clinical trial, hematological and chemistry assessments were at 1, 3, 5, and 8 weeks, then every 4 weeks. Thyroid stimulating hormone (TSH) was measured every 12 weeks. Monthly pregnancy testing should be performed during combination therapy and for 6 months after discontinuing therapy. The entrance criteria used for the clinical studies of COPEGUS and PEGASYS may be considered as a guideline to acceptable baseline values for initiation of treatment: Platelet count greater than or equal to 90,000 cells/mm³ (as low as 75,000 cells/mm³ in HCV patients with cirrhosis or 70,000 cells/mm³ in patients with CHC and HIV) Absolute neutrophil count (ANC) greater than or equal to 1500 cells/mm³ TSH and T4 within normal limits or adequately controlled thyroid function CD4+ cell count greater than or equal to 200 cells/mm³ or CD4+ cell count greater than or equal to 100 cells/mm³ but less than 200 cells/mm³ and HIV-1 RNA less than 5,000 copies/mL in patients coinfected with HIV Hemoglobin greater than or equal to 12 g/dL for women and greater than or equal to 13 g/dL for men in CHC monoinfected patients Hemoglobin greater than or equal to 11 g/dL for women and greater than or equal to 12 g/dL for men in patients with CHC and HIV Patient Counseling Information See FDA-approved patient labeling (Medication Guide) Pregnancy Patients must be informed that ribavirin may cause birth defects and/or death of the exposed fetus. COPEGUS therapy must not be used by women who are pregnant or by men whose female partners are pregnant. Extreme care must be taken to avoid pregnancy in female patients and in female partners of male patients taking COPEGUS therapy and for 6 months post therapy. Patients should use two reliable methods of birth control while taking COPEGUS therapy and for 6 months post therapy. COPEGUS therapy should not be initiated until a report of a negative pregnancy test has been obtained immediately prior to initiation of therapy. Patients must perform a pregnancy test monthly during therapy and for 6 months post therapy. Female patients of childbearing potential and male patients with female partners of childbearing potential must be advised of the teratogenic/embryocidal risks and must be instructed to practice effective contraception during COPEGUS therapy and for 6 months post therapy. Patients should be advised to notify the healthcare provider immediately in the event of a pregnancy [see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS]. Anemia The most common adverse event associated with ribavirin is anemia, which may be severe [see BOXED WARNING, WARNINGS AND PRECAUTIONS and ADVERSE REACTIONS]. Patients should be advised that laboratory evaluations are required prior to starting COPEGUS therapy and periodically thereafter [see WARNINGS AND PRECAUTIONS]. It is advised that patients be well hydrated, especially during the initial stages of treatment. Patients who develop dizziness, confusion, somnolence, and fatigue should be cautioned to avoid driving or operating machinery. Patients should be advised to take COPEGUS with food. Patients should be questioned about prior history of drug abuse before initiating COPEGUS/PEGASYS, as relapse of drug addiction and drug overdoses have been reported in patients treated with interferons. Patients should be advised not to drink alcohol, as alcohol may exacerbate chronic hepatitis C infection. Patients should be informed about what to do in the event they miss a dose of COPEGUS. The missed doses should be taken as soon as possible during the same day. Patients should not double the next dose. Patients should be advised to call their healthcare provider if they have questions. Patients should be informed that the effect of PEGASYS/COPEGUS treatment of hepatitis C infection on transmission is not known, and that appropriate precautions to prevent transmission of hepatitis C virus during treatment or in the event of treatment failure should be taken. Patients should be informed regarding the potential benefits and risks attendant to the use of COPEGUS. Instructions on appropriate use should be given, including review of the contents of the enclosed MEDICATION GUIDE, which is not a disclosure of all or possible adverse effects. Nonclinical Toxicology Carcinogenesis, Mutagenesis, Impairment Of Fertility Carcinogenesis In a p53 (+/-) mouse carcinogenicity study up to the maximum tolerated dose of 100 mg/kg/day, ribavirin was not oncogenic. Ribavirin was also not oncogenic in a rat 2-year carcinogenicity study at doses up to the maximum tolerated dose of 60 mg/kg/day. On a body surface area basis, these doses are approximately 0.5 and 0.6 times the maximum recommended daily human dose of ribavirin, respectively. Mutagenesis Ribavirin demonstrated mutagenic activity in the in vitro mouse lymphoma assay. No clastogenic activity was observed in an in vivo mouse micronucleus assay at doses up to 2000 mg/kg. However, results from studies published in the literature show clastogenic activity in the in vivo mouse micronucleus assay at oral doses up to 2000 mg/kg. A dominant lethal assay in rats was negative, indicating that if mutations occurred in rats they were not transmitted through male gametes. Impairment of Fertility In a fertility study in rats, ribavirin showed a marginal reduction in sperm counts at the dose of 100 mg/kg/day with no effect on fertility. Upon cessation of treatment, total recovery occurred after 1 spermatogenesis cycle. Abnormalities in sperm were observed in studies in mice designed to evaluate the time course and reversibility of ribavirin-induced testicular degeneration at doses of 15 to 150 mg/kg/day (approximately 0.1 to 0.8 times the maximum recommended daily human dose of ribavirin) administered for 3 to 6 months. Upon cessation of treatment, essentially total recovery from ribavirin-induced testicular toxicity was apparent within 1 or 2 spermatogenic cycles. Female patients of childbearing potential and male patients with female partners of childbearing potential should not receive COPEGUS unless the patient and his/her partner are using effective contraception (two reliable forms). Based on a multiple dose half-life (t½) of ribavirin of 12 days, effective contraception must be utilized for 6 months post therapy (i.e., 15 half-lives of clearance for ribavirin). No reproductive toxicology studies have been performed using PEGASYS in combination with COPEGUS. However, peginterferon alfa-2a and ribavirin when administered separately, each has adverse effects on reproduction. It should be assumed that the effects produced by either agent alone would also be caused by the combination of the two agents. Use In Specific Populations Pregnancy Category X [see CONTRAINDICATIONS]. Ribavirin produced significant embryocidal and/or teratogenic effects in all animal species in which adequate studies have been conducted. Malformations of the skull, palate, eye, jaw, limbs, skeleton, and gastrointestinal tract were noted. The incidence and severity of teratogenic effects increased with escalation of the drug dose. Survival of fetuses and offspring was reduced [see CONTRAINDICATIONS and WARNINGS AND PRECAUTIONS]. In conventional embryotoxicity/teratogenicity studies in rats and rabbits, observed no-effect dose levels were well below those for proposed clinical use (0.3 mg/kg/day for both the rat and rabbit; approximately 0.06 times the recommended daily human dose of ribavirin). No maternal toxicity or effects on offspring were observed in a peri/postnatal toxicity study in rats dosed orally at up to 1 mg/kg/day (approximately 0.01 times the maximum recommended daily human dose of ribavirin). Treatment and Post-Treatment: Potential Risk to the Fetus Ribavirin is known to accumulate in intracellular components from where it is cleared very slowly. It is not known whether ribavirin is contained in sperm, and if so, will exert a potential teratogenic effect upon fertilization of the ova. However, because of the potential human teratogenic effects of ribavirin, male patients should be advised to take every precaution to avoid risk of pregnancy for their female partners. COPEGUS should not be used by pregnant women or by men whose female partners are pregnant. Female patients of childbearing potential and male patients with female partners of childbearing potential should not receive COPEGUS unless the patient and his/her partner are using effective contraception (two reliable forms) during therapy and for 6 months post therapy [see CONTRAINDICATIONS]. Ribavirin Pregnancy Registry A Ribavirin Pregnancy Registry has been established to monitor maternal-fetal outcomes of pregnancies of female patients and female partners of male patients exposed to ribavirin during treatment and for 6 months following cessation of treatment. Healthcare providers and patients are encouraged to report such cases by calling 1-800-593-2214. Nursing Mothers It is not known whether ribavirin is excreted in human milk. Because many drugs are excreted in human milk and to avoid any potential for serious adverse reactions in nursing infants from ribavirin, a decision should be made either to discontinue nursing or therapy with COPEGUS, based on the importance of the therapy to the mother. Pediatric Use Pharmacokinetic evaluations in pediatric patients have not been performed. Safety and effectiveness of COPEGUS have not been established in patients below the age of 5 years. Geriatric Use Clinical studies of COPEGUS and PEGASYS did not include sufficient numbers of subjects aged 65 or over to determine whether they respond differently from younger subjects. Specific pharmacokinetic evaluations for ribavirin in the elderly have not been performed. The risk of toxic reactions to this drug may be greater in patients with impaired renal function. The dose of COPEGUS should be reduced in patients with creatinine clearance less than or equal to 50 mL/min; and the dose of PEGASYS should be reduced in patients with creatinine clearance less than 30 mL/min [see DOSAGE AND ADMINISTRATION; Use In Specific Populations]. Race A pharmacokinetic study in 42 subjects demonstrated there is no clinically significant difference in ribavirin pharmacokinetics among Black (n=14), Hispanic (n=13) and Caucasian (n=15) subjects. Renal Impairment Renal function should be evaluated in all patients prior to initiation of COPEGUS by estimating the patient's creatinine clearance. A clinical trial evaluated treatment with COPEGUS and PEGASYS in 50 CHC subjects with moderate (creatinine clearance 30 – 50 mL/min) or severe (creatinine clearance less than 30 mL/min) renal impairment or end stage renal disease (ESRD) requiring chronic hemodialysis (HD). In 18 subjects with ESRD receiving chronic HD, COPEGUS was administered at a dose of 200 mg daily with no apparent difference in the adverse event profile in comparison to subjects with normal renal function. Dose reductions and temporary interruptions of COPEGUS (due to COPEGUS-related adverse reactions, mainly anemia) were observed in up to one-third ESRD/HD subjects during treatment; and only one-third of these subjects received COPEGUS for 48 weeks. Ribavirin plasma exposures were approximately 20% lower in subjects with ESRD on HD compared to subjects with normal renal function receiving the standard 1000/1200 mg COPEGUS daily dose. Subjects with moderate (n=17) or severe (n=14) renal impairment did not tolerate 600 mg or 400 mg daily doses of COPEGUS, respectively, due to COPEGUS-related adverse reactions, mainly anemia, and exhibited 20% to 30% higher ribavirin plasma exposures (despite frequent dose modifications) compared to subjects with normal renal function (creatinine clearance greater than 80 mL/min) receiving the standard dose of COPEGUS. Discontinuation rates were higher in subjects with severe renal impairment compared to that observed in subjects with moderate renal impairment or normal renal function. Pharmacokinetic modeling and simulation indicate that a dose of 200 mg daily in patients with severe renal impairment and a dose of 200 mg daily alternating with 400 mg the following day in patients with moderate renal impairment will provide plasma ribavirin exposure similar to patients with normal renal function receiving the approved regimen of COPEGUS. These doses have not been studied in patients [see DOSAGE AND ADMINISTRATION and CLINICAL PHARMACOLOGY]. Based on the pharmacokinetic and safety results from this trial, patients with creatinine clearance less than or equal to 50 mL/min should receive a reduced dose of COPEGUS; and patients with creatinine clearance less than 30 mL/min should receive a reduced dose of PEGASYS. The clinical and hematologic status of patients with creatinine clearance less than or equal to 50 mL/min receiving COPEGUS should be carefully monitored. Patients with clinically significant laboratory abnormalities or adverse reactions which are persistently severe or worsening should have therapy withdrawn [see DOSAGE AND ADMINISTRATION, CLINICAL PHARMACOLOGY, and PEGASYS Package Insert]. Hepatic Impairment The effect of hepatic impairment on the pharmacokinetics of ribavirin following administration of COPEGUS has not been evaluated. The clinical trials of COPEGUS were restricted to patients with Child-Pugh class A disease. Gender No clinically significant differences in the pharmacokinetics of ribavirin were observed between male and female subjects. Ribavirin pharmacokinetics, when corrected for weight, are similar in male and female patients. Organ Transplant Recipients The safety and efficacy of PEGASYS and COPEGUS treatment have not been established in patients with liver and other transplantations. As with other alpha interferons, liver and renal graft rejections have been reported on PEGASYS, alone or in combination with COPEGUS [see ADVERSE REACTIONS].