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CLINICAL PHARMACOLOGY Mechanism Of Action TRIZIVIR is an antiretroviral agent [see Microbiology]. Pharmacokinetics Pharmacokinetics in Adults In a single-dose, 3-way crossover bioavailability trial of 1 TRIZIVIR tablet versus 1 ZIAGEN tablet (300 mg), 1 EPIVIR tablet (150 mg), plus 1 RETROVIR tablet (300 mg) administered simultaneously in healthy subjects (n = 24), there was no difference in the extent of absorption, as measured by the area under the plasma concentration-time curve (AUC) and maximal peak concentration (Cmax), of all 3 components. One TRIZIVIR tablet was bioequivalent to 1 ZIAGEN tablet (300 mg), 1 EPIVIR tablet (150 mg), plus 1 RETROVIR tablet (300 mg) following single-dose administration to fasting healthy subjects (n = 24). Abacavir: Following oral administration, abacavir is rapidly absorbed and extensively distributed. After oral administration of 300 mg of abacavir twice daily in 20 subjects, Cmax was 3.0 ± 0.89 mcg per mL (mean ± SD) and AUC(0-12 h) was 6.02 ± 1.73 mcg•hour per mL. Binding of abacavir to human plasma proteins is approximately 50% and was independent of concentration. Total blood and plasma drug-related radioactivity concentrations are identical, demonstrating that abacavir readily distributes into erythrocytes. The primary routes of elimination of abacavir are metabolism by alcohol dehydrogenase to form the 5'-carboxylic acid and glucuronyl transferase to form the 5'-glucuronide. Lamivudine: Following oral administration, lamivudine is rapidly absorbed and extensively distributed. Binding to plasma protein is low. Approximately 70% of an intravenous dose of lamivudine is recovered as unchanged drug in the urine. Metabolism of lamivudine is a minor route of elimination. In humans, the only known metabolite is the trans-sulfoxide metabolite (approximately 5% of an oral dose after 12 hours). Zidovudine: Following oral administration, zidovudine is rapidly absorbed and extensively distributed. Binding to plasma protein is low. Zidovudine is eliminated primarily by hepatic metabolism. The major metabolite of zidovudine is GZDV. GZDV AUC is about 3-fold greater than the zidovudine AUC. Urinary recovery of zidovudine and GZDV accounts for 14% and 74% of the dose following oral administration, respectively. A second metabolite, 3'-amino-3'deoxythymidine (AMT), has been identified in plasma. The AMT AUC was one-fifth of the zidovudine AUC. In humans, abacavir, lamivudine, and zidovudine are not significantly metabolized by cytochrome P450 enzymes. The pharmacokinetic properties of abacavir, lamivudine, and zidovudine in fasting subjects are summarized in Table 3. Table 3: Pharmacokinetic Parametersa for Abacavir, Lamivudine, and Zidovudine in Adults Parameter Abacavir Lamivudine Zidovudine Oral bioavailability (%) 86 ± 25 n = 6 86 ± 16 n = 12 64 ± 10 n = 5 Apparent volume of distribution (L/kg) 0.86 ± 0.15 n = 6 1.3 ± 0.4 n = 20 1.6 ± 0.6 n = 8 Systemic clearance (L/h/kg) 0.80 ± 0.24 n = 6 0.33 ± 0.06 n = 20 1.6 ± 0.6 n = 6 Renal clearance (L/h/kg) 0.007 ± 0.008 n = 6 0.22 ± 0.06 n = 20 0.34 ± 0.05 n = 9 Elimination half-life (h) 1.45 ± 0.32 n = 20 5 to 7b 0.5 to 3b aData presented as mean ± standard deviation except where noted. bApproximate range. Effect of Food on Absorption of TRIZIVIR Administration with food in a single-dose bioavailability trial resulted in lower Cmax, similar to results observed previously for the reference formulations. The average [90% CI] decrease in abacavir, lamivudine, and zidovudine Cmax was 32% [24% to 38%], 18% [10% to 25%], and 28% [13% to 40%], respectively, when administered with a high-fat meal, compared with administration under fasted conditions. Administration of TRIZIVIR with food did not alter the extent of abacavir, lamivudine, and zidovudine absorption (AUC), as compared with administration under fasted conditions (n = 24) [see DOSAGE AND ADMINISTRATION]. Special Populations Renal Impairment: TRIZIVIR: The effect of renal impairment on the combination of abacavir, lamivudine, and zidovudine has not been evaluated (see the U.S. prescribing information for the individual abacavir, lamivudine, and zidovudine components). Hepatic Impairment: TRIZIVIR: The effect of hepatic impairment on the combination of abacavir, lamivudine, and zidovudine has not been evaluated (see the U.S. prescribing information for the individual abacavir, lamivudine, and zidovudine components). Pregnancy: Abacavir: No data are available on the pharmacokinetics of abacavir during pregnancy. Lamivudine: Lamivudine pharmacokinetics were studied in 36 pregnant women during 2 clinical trials conducted in South Africa. Lamivudine pharmacokinetics in pregnant women were similar to those seen in non-pregnant adults and in postpartum women. Lamivudine concentrations were generally similar in maternal, neonatal, and umbilical cord serum samples. Zidovudine: Zidovudine pharmacokinetics have been studied in a Phase 1 trial of 8 women during the last trimester of pregnancy. Zidovudine pharmacokinetics were similar to those of nonpregnant adults. Consistent with passive transmission of the drug across the placenta, zidovudine concentrations in neonatal plasma at birth were essentially equal to those in maternal plasma at delivery. Although data are limited, methadone maintenance therapy in 5 pregnant women did not appear to alter zidovudine pharmacokinetics. Geriatric Patients: The pharmacokinetics of abacavir, lamivudine, and zidovudine have not been studied in subjects over 65 years of age. Gender: There are no significant or clinically relevant gender differences in the pharmacokinetics of the individual components (abacavir, lamivudine, or zidovudine) based on the available information that was analyzed for each of the individual components. Race: Abacavir and Lamivudine: There are no significant or clinically relevant racial differences in pharmacokinetics of abacavir or lamivudine based on the available information that was analyzed for each of the individual components. Zidovudine: The pharmacokinetics of zidovudine with respect to race have not been determined. Drug Interactions The drug interaction trials described were conducted with abacavir, lamivudine or zidovudine as single entities; no drug interaction trials have been conducted using TRIZIVIR. No clinically significant drug interactions are expected between abacavir, lamivudine, and zidovudine. Cytochrome P450 Enzymes: Abacavir, lamivudine, and zidovudine are not significantly metabolized by cytochrome P450 enzymes; therefore, it is unlikely that clinically significant drug interactions will occur with drugs metabolized through these pathways. Glucuronyl Transferase: Due to the common metabolic pathways of abacavir and zidovudine via glucuronyl transferase, 15 HIV-1-infected subjects were enrolled in a crossover trial evaluating single doses of abacavir (600 mg), lamivudine (150 mg), and zidovudine (300 mg) alone or in combination. Analysis showed no clinically relevant changes in the pharmacokinetics of abacavir with the addition of lamivudine or zidovudine or the combination of lamivudine and zidovudine. Lamivudine exposure (AUC decreased 15%) and zidovudine exposure (AUC increased 10%) did not show clinically relevant changes with concurrent abacavir. Other Interactions Ethanol: Abacavir has no effect on the pharmacokinetic properties of ethanol. Ethanol decreases the elimination of abacavir causing an increase in overall exposure. Interferon Alfa: There was no significant pharmacokinetic interaction between lamivudine and interferon alfa in a trial of 19 healthy male subjects. Methadone: In a trial of 11 HIV-1-infected subjects receiving methadone-maintenance therapy (40 mg and 90 mg daily), with 600 mg of abacavir twice daily (twice the currently recommended dose), oral methadone clearance increased 22% (90% CI: 6% to 42%) [see DRUG INTERACTIONS]. The addition of methadone has no clinically significant effect on the pharmacokinetic properties of abacavir. Ribavirin: 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-1/HCV virologic suppression) interaction was observed when ribavirin and lamivudine (n = 18), stavudine (n = 10), or zidovudine (n = 6) were coadministered as part of a multi-drug regimen to HIV-1/HCV co-infected subjects [see WARNINGS AND PRECAUTIONS]. The effects of other coadministered drugs on abacavir, lamivudine, or zidovudine are provided in Table 4. Table 4: Effect of Coadministered Drugs on Abacavir, Lamivudine, and Zidovudine AUCa Coadministered Drug and Dose Drug and Dose n Concentrations of Abacavir, Lamivudine, or Zidovudine Concentration of Coadministered Drug AUC Variability Ethanol 0.7 g/kg Abacavir single 600 mg 24 ↑41% 90% CI: 35% to 48% ↔b Nelfinavir 750 mg every 8 h x 7 to 10 days Lamivudine Single 150 mg 11 ↑10% 95% CI: 1% to 20% ↔ Trimethoprim 160 mg/ Sulfamethoxazole 800 mg daily x 5 days Lamivudine Single 300 mg 14 ↑43% 90% CI: 32% to 55% ↔ Atovaquone 750 mg every 12 h with food Zidovudine 200 mg every 8 h 14 ↑31% Range: 23% to 78%c ↔ Clarithromycin 500 mg twice daily Zidovudine 100 mg every 4 h x 7 days 4 ↓12% Range: ↓34% to ↑14% Not Reported Fluconazole 400 mg daily Zidovudine 200 mg every 8 h 12 ↑74% 95% CI: 54% to 98% Not Reported Methadone 30 to 90 mg daily Zidovudine 200 mg every 4 h 9 ↑43% Range: 16% to 64%c ↔ Nelfinavir 750 mg every 8 h x 7 to 10 days Zidovudine single 200 mg 11 ↓35% Range: 28% to 41% ↔ Probenecid 500 mg every 6 h x 2 days Zidovudine 2 mg/kg every 8 h x 3 days 3 ↑106% Range: 100% to 170%c Not Assessed Rifampin 600 mg daily x 14 days Zidovudine 200 mg every 8 h x 14 days 8 ↓47% 90% CI: 41% to 53% Not Assessed Ritonavir 300 mg every 6 h x 4 days Zidovudine 200 mg every 8 h x 4 days 9 ↓25% 95% CI: 15% to 34% ↔ Valproic acid 250 mg or 500 mg every 8 h x 4 days Zidovudine 100 mg every 8 h x 4 days 6 ↑80% Range: 64% to 130%c Not Assessed ↑ = Increase; ↓ = Decrease; ↔ = no significant change; AUC = area under the concentration versus time curve; CI = confidence interval. aSee DRUG INTERACTIONS for additional information on drug interactions. bThe drug-drug interaction was only evaluated in males. cEstimated range of percent difference. Microbiology Mechanism of Action Abacavir: Abacavir is a carbocyclic synthetic nucleoside analogue. Abacavir is converted by cellular enzymes to the active metabolite, carbovir triphosphate (CBV-TP), an analogue of deoxyguanosine-5'-triphosphate (dGTP). CBV-TP inhibits the activity of HIV-1 reverse transcriptase (RT) both by competing with the natural substrate dGTP and by its incorporation into viral DNA. Lamivudine: Lamivudine is a synthetic nucleoside analogue. Intracellularly, lamivudine is phosphorylated to its active 5'-triphosphate metabolite, lamivudine triphosphate (3TC-TP). The principal mode of action of 3TC-TP is inhibition of RT via DNA chain termination after incorporation of the nucleotide analogue. Zidovudine: Zidovudine is a synthetic nucleoside analogue. Intracellularly, zidovudine is phosphorylated to its active 5'-triphosphate metabolite, zidovudine triphosphate (ZDV-TP). The principal mode of action of ZDV-TP is inhibition of RT via DNA chain termination after incorporation of the nucleotide analogue. Antiviral Activity Abacavir: The antiviral activity of abacavir against HIV-1 was assessed in a number of cell lines including primary monocytes/macrophages and peripheral blood mononuclear cells (PBMCs). EC50 values ranged from 3.7 to 5.8 microM (1 microM = 0.28 mcg per mL) and 0.07 to 1.0 microM against HIV-1IIIB and HIV-1BaL, respectively, and the mean EC50 value was 0.26 ± 0.18 microM against 8 clinical isolates. The median EC50 values of abacavir were 344 nM (range: 14.8 to 676 nM), 16.9 nM (range: 5.9 to 27.9 nM), 8.1 nM (range: 1.5 to 16.7 nM), 356 nM (range: 35.7 to 396 nM), 105 nM (range: 28.1 to 168 nM), 47.6 nM (range: 5.2 to 200 nM), 51.4 nM (range: 7.1 to 177 nM), and 282 nM (range: 22.4 to 598 nM) against HIV-1 clades A-G and group O viruses (n = 3 except n = 2 for clade B), respectively. The EC50 values against HIV-2 isolates (n = 4), ranged from 0.024 to 0.49 microM. Lamivudine: The antiviral activity of lamivudine against HIV-1 was assessed in a number of cell lines including monocytes and PBMCs using standard susceptibility assays. EC50 values were in the range of 0.003 to 15 microM (1 microM = 0.23 mcg per mL). The median EC50 values of lamivudine were 60 nM (range: 20 to 70 nM), 35 nM (range: 30 to 40 nM), 30 nM (range: 20 to 90 nM), 20 nM (range: 3 to 40 nM), 30 nM (range: 1 to 60 nM), 30 nM (range: 20 to 70 nM), 30 nM (range: 3 to 70 nM), and 30 nM (range: 20 to 90 nM) against HIV-1 clades AG and group O viruses (n = 3 except n = 2 for clade B), respectively. The EC50 values against HIV-2 isolates (n = 4) ranged from 0.003 to 0.120 microM in PBMCs. Ribavirin (50 microM) used in the treatment of chronic HCV infection decreased the anti-HIV-1 activity of lamivudine by 3.5-fold in MT-4 cells. Zidovudine: The antiviral activity of zidovudine against HIV-1 was assessed in a number of cell lines including monocytes and fresh human peripheral blood lymphocytes. The EC50 and EC90 values for zidovudine were 0.01 to 0.49 microM (1 microM = 0.27 mcg per mL) and 0.1 to 9 microM, respectively. HIV-1 from therapy-naive subjects with no amino acid substitutions associated with resistance gave median EC50 values of 0.011 microM (range: 0.005 to 0.110 microM) from Virco (n = 92 baseline samples) and 0.0017 microM (range: 0.006 to 0.0340 microM) from Monogram Biosciences (n = 135 baseline samples). The EC50 values of zidovudine against different HIV-1 clades (A-G) ranged from 0.00018 to 0.02 microM, and against HIV-2 isolates from 0.00049 to 0.004 microM. Ribavirin has been found to inhibit the phosphorylation of zidovudine in cell culture. Neither abacavir, lamivudine, nor zidovudine were antagonistic to tested anti-HIV agents, with the exception of stavudine where an antagonistic relationship with zidovudine has been demonstrated in cell culture. See full prescribing information for ZIAGEN (abacavir), EPIVIR (lamivudine), RETROVIR (zidovudine). Resistance HIV-1 isolates with reduced susceptibility to abacavir, lamivudine, or zidovudine have been selected in cell culture and were also recovered from subjects treated with abacavir, lamivudine, and zidovudine, or the combinations of the individual components. Abacavir and Lamivudine: HIV-1 isolates with reduced susceptibility to the combination of abacavir and lamivudine have been selected in cell culture with amino acid substitutions, K65R, L74V, Y115F, and M184V/I emerging in HIV-1 RT. M184V or I substitutions resulted in high-level resistance to lamivudine and an approximately 2-fold decrease in susceptibility to abacavir. Substitutions K65R, L74M, or Y115F with M184V or I conferred a 7- to 8-fold reduction in abacavir susceptibility, and combinations of three substitutions were required to confer more than an 8-fold reduction in susceptibility. Zidovudine: Genotypic analyses of the isolates selected in cell culture and recovered from zidovudine-treated subjects showed thymidine analog mutation (TAM) substitutions in HIV-1 RT (M41L, D67N, K70R, L210W, T215Y or F, and K219E/R/H/Q/N) that confer zidovudine resistance. In general, higher levels of resistance were associated with a greater number of substitutions. In some subjects harboring zidovudine-resistant virus at baseline, phenotypic sensitivity to zidovudine was restored by 12 weeks of treatment with lamivudine and zidovudine. Cross-resistance Cross-resistance has been observed among NRTIs. The combination of abacavir/lamivudine has demonstrated decreased susceptibility to viruses with a K65R substitution with or without an M184V/I substitution, viruses with L74V plus the M184V/I substitution, and viruses with TAM substitutions (M41L, D67N, K70R, L210W, T215Y/F, K219 E/R/H/Q/N) plus M184V. An increasing number of TAMs is associated with a progressive reduction in abacavir susceptibility. TAMs are selected by zidovudine and confer cross-resistance to abacavir, didanosine, stavudine, and tenofovir. Cross-resistance between lamivudine and zidovudine has not been reported. Animal Toxicology And/Or Pharmacology Myocardial degeneration was found in mice and rats following administration of abacavir for 2 years. The systemic exposures were equivalent to 7 to 24 times the expected systemic exposure in humans at a dose of 600 mg. The clinical relevance of this finding has not been determined. Clinical Studies The following trial was conducted with the individual components of TRIZIVIR [see CLINICAL PHARMACOLOGY]. CNA3005 was a multicenter, double-blind, controlled trial in which 562 HIV-1-infected, therapy-naive adults were randomized to receive either ZIAGEN (300 mg twice daily) plus COMBIVIR® (lamivudine 150 mg/zidovudine 300 mg twice daily), or indinavir (800 mg 3 times a day) plus COMBIVIR twice daily. The trial was stratified at randomization by pre-entry plasma HIV-1 RNA 10,000 to 100,000 copies per mL and plasma HIV-1 RNA greater than 100,000 copies per mL. Trial participants were male (87%), Caucasian (73%), black (15%), and Hispanic (9%). At baseline the median age was 36 years,; the median pretreatment CD4+ cell count was 360 cells per mm³, and median plasma HIV-1 RNA was 4.8 log10 copies per mL. Proportions of subjects with plasma HIV-1 RNA less than 400 copies per mL (using Roche AMPLICOR HIV-1 MONITOR® Test) through 48 weeks of treatment are summarized in Table 5. Table 5: Outcomes of Randomized Treatment through Week 48 (CNA3005) Outcome ZIAGEN plus Lamivudine/ Zidovudine (n = 262) Indinavir plus Lamivudine/ Zidovudine (n = 265) Respondera 49% 50% Virologic failureb 31% 28% Discontinued due to adverse reactions 10% 12% Discontinued due to other reasonsc 11% 10% aSubjects achieved and maintained confirmed HIV-1 RNA less than 400 copies per mL. bIncludes viral rebound and failure to achieve confirmed less than 400 copies per mL by Week 48. cIncludes consent withdrawn, lost to follow-up, protocol violations, those with missing data, clinical progression, and other. Treatment response by plasma HIV-1 RNA strata is shown in Table 6. Table 6: Proportions of Responders through Week 48 by Screening Plasma HIV-1 RNA Levels (CNA3005) Screening HIV-1 RNA (copies/mL) ZIAGEN plus Lamivudine/ Zidovudine (n = 262) Indinavir plus Lamivudine/ Zidovudine (n = 265) < 400 copies/mL n < 400 copies/mL n ≥ 10,000 - ≤ 100,000 50% 166 48% 165 > 100,000 48% 96 52% 100 In subjects with baseline viral load greater than 100,000 copies per mL, percentages of subjects with HIV-1 RNA levels less than 50 copies per mL were 31% in the group receiving abacavir vs. 45% in the group receiving indinavir. Through Week 48, an overall mean increase in CD4+ cell count of about 150 cells per mm³ was observed in both treatment arms. Through Week 48, 9 subjects (3.4%) in the group receiving abacavir (6 CDC classification C events and 3 deaths) and 3 subjects (1.5%) in the group receiving indinavir (2 CDC classification C events and 1 death) experienced clinical disease progression.

Find Lowest Prices on TRIZIVIR® (abacavir, lamivudine, and zidovudine)Tablets WARNING HYPERSENSITIVITY REACTIONS, HEMATOLOGIC TOXICITY, MYOPATHY, LACTIC ACIDOSIS AND SEVERE HEPATOMEGALY WITH STEATOSIS, and EXACERBATIONS OF HEPATITIS B Hypersensitivity Reactions Serious and sometimes fatal hypersensitivity reactions, with multiple organ involvement, have occurred with abacavir, a component of TRIZIVIR (abacavir, lamivudine, and zidovudine). Patients who carry the HLA-B*5701 allele are at a higher risk of a hypersensitivity reaction to abacavir; although, hypersensitivity reactions have occurred in patients who do not carry the HLA-B*5701 allele [see WARNINGS AND PRECAUTIONS]. TRIZIVIR is contraindicated in patients with a prior hypersensitivity reaction to abacavir and in HLA-B*5701-positive patients [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS]. All patients should be screened for the HLA-B*5701 allele prior to initiating therapy with TRIZIVIR or reinitiation of therapy with TRIZIVIR, unless patients have a previously documented HLA-B*5701 allele assessment. Discontinue TRIZIVIR immediately if a hypersensitivity reaction is suspected, regardless of HLA-B*5701 status and even when other diagnoses are possible [see CONTRAINDICATIONS, WARNINGS AND PRECAUTIONS]. Following a hypersensitivity reaction to TRIZIVIR, NEVER restart TRIZIVIR or any other abacavir-containing product because more severe symptoms, including death, can occur within hours. Similar severe reactions have also occurred rarely following the reintroduction of abacavir-containing products in patients who have no history of abacavir hypersensitivity [see WARNINGS AND PRECAUTIONS]. Hematologic Toxicity Zidovudine, a component of TRIZIVIR, has been associated with hematologic toxicity, including neutropenia and severe anemia, particularly in patients with advanced Human Immunodeficiency Virus (HIV-1) disease [see WARNINGS AND PRECAUTIONS]. Myopathy Prolonged use of zidovudine has been associated with symptomatic myopathy [see WARNINGS AND PRECAUTIONS]. Lactic Acidosis and Severe Hepatomegaly with Steatosis Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogues and other antiretrovirals. Discontinue TRIZIVIR if clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity occur [see WARNINGS AND PRECAUTIONS]. Exacerbations of Hepatitis B Severe acute exacerbations of hepatitis B have been reported in patients who are co-infected with hepatitis B virus (HBV) and HIV-1 and have discontinued lamivudine, a component of TRIZIVIR. Hepatic function should be monitored closely with both clinical and laboratory follow-up for at least several months in patients who discontinue TRIZIVIR and are co-infected with HIV-1 and HBV. If appropriate, initiation of anti-hepatitis B therapy may be warranted [see WARNINGS AND PRECAUTIONS]. DESCRIPTION TRIZIVIR tablets contain the following 3 synthetic nucleoside analogues: abacavir (ZIAGEN), lamivudine (also known as EPIVIR or 3TC), and zidovudine (also known as RETROVIR, azidothymidine, or ZDV) with inhibitory activity against HIV-1. TRIZIVIR tablets are for oral administration. Each film-coated tablet contains the active ingredients 300 mg of abacavir as abacavir sulfate, 150 mg of lamivudine, and 300 mg of zidovudine, and the inactive ingredients magnesium stearate, microcrystalline cellulose, and sodium starch glycolate. The tablets are coated with a film (OPADRY® green 03B11434) that is made of FD&C Blue No. 2, hypromellose, polyethylene glycol, titanium dioxide, and yellow iron oxide. Abacavir Sulfate The chemical name of abacavir sulfate is (1S,cis)-4-[2-amino-6(cyclopropylamino)-9H-purin-9-yl]-2-cyclopentene-1-methanol sulfate (salt) (2:1). Abacavir sulfate is the enantiomer with 1S, 4R absolute configuration on the cyclopentene ring. It has a molecular formula of (C14H18N6O)2•H2SO4 and a molecular weight of 670.76 g per mol. It has the following structural formula: Abacavir sulfate is a white to off-white solid and soluble in water. Dosages are expressed in terms of abacavir. Lamivudine The chemical name of lamivudine is (2R,cis)-4-amino-1-(2-hydroxymethyl-1,3oxathiolan-5-yl)-(1H)-pyrimidin-2-one. Lamivudine is the (-)enantiomer of a dideoxy analogue of cytidine. Lamivudine has also been referred to as (-)2',3'-dideoxy, 3'-thiacytidine. It has a molecular formula of C8H11N3O3S and a molecular weight of 229.3 g per mol. It has the following structural formula: Lamivudine is a white to off-white crystalline solid and is soluble in water. Zidovudine The chemical name of zidovudine is 3'-azido-3'-deoxythymidine. It has a molecular formula of C10H13N5O4 and a molecular weight of 267.24 g per mol. It has the following structural formula: Zidovudine is a white to beige, odorless, crystalline solid with a solubility of 20.1 mg per mL in water at 25°C.

INDICATIONS TRIZIVIR is indicated in combination with other antiretrovirals or alone for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Limitations of Use Limited data exist on the use of TRIZIVIR alone in patients with higher baseline viral load levels (greater than 100,000 copies per mL) [see Clinical Studies]. DOSAGE AND ADMINISTRATION Screening For HLA-B*5701 Allele Prior To Starting TRIZIVIR Screen for the HLA-B*5701 allele prior to initiating therapy with TRIZIVIR [see BOXED WARNING, WARNINGS AND PRECAUTIONS]. Recommended Dosage For Adults And Pediatric Patients Weighing At Least 40 kg The recommended dosage of TRIZIVIR is one tablet taken orally twice daily with or without food. Not Recommended Due To Lack Of Dosage Adjustment Because TRIZIVIR is a fixed-dose tablet and cannot be dose adjusted, TRIZIVIR is not recommended in: pediatric patients who weigh less than 40 kg [see Use in Specific Populations] patients with creatinine clearance less than 50 mL per minute [see Use In Specific Populations] patients with mild hepatic impairment. TRIZIVIR is contraindicated in patients with moderate or severe hepatic impairment [see CONTRAINDICATIONS, Use In Specific Populations]. HOW SUPPLIED Dosage Forms And Strengths TRIZIVIR tablets contain 300 mg of abacavir as abacavir sulfate, 150 mg of lamivudine, and 300 mg of zidovudine. The tablets are blue-green, capsule-shaped, film-coated, and imprinted with “GX LL1” on one side with no markings on the reverse side. Storage And Handling TRIZIVIR is available as tablets. Each tablet contains 300 mg of abacavir as abacavir sulfate, 150 mg of lamivudine, and 300 mg of zidovudine. The tablets are blue-green capsule-shaped, film-coated, and imprinted with GX LL1 on one side with no markings on the reverse side. They are packaged as follows: Bottles of 60 tablets (NDC 49702-217-18). Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F) (see USP Controlled Room Temperature). Manufactured for: ViiV Healthcare, Research Triangle Park, NC 27709 by: GlaxoSmithKline Research Triangle Park, NC 27709. Revised: September 2015

PATIENT INFORMATION TRIZIVIR® (TRY-zih-veer) (abacavir, lamivudine, and zidovudine) tablets What is the most important information I should know about TRIZIVIR? TRIZIVIR can cause serious side effects, including: Serious allergic reactions (hypersensitivity reaction) that can cause death have happened with TRIZIVIR and other abacavir-containing products. Your risk of this allergic reaction is much higher if you have a gene variation called HLA-B*5701. Your healthcare provider can determine with a blood test if you have this gene variation. If you get a symptom from 2 or more of the following groups while taking TRIZIVIR, call your healthcare provider right away to find out if you should stop taking TRIZIVIR. Symptom(s) Group 1 Fever Group 2 Rash Group 3 Nausea, vomiting, diarrhea, abdominal (stomach area) pain Group 4 Generally ill feeling, extreme tiredness, or achiness Group 5 Shortness of breath, cough, sore throat A list of these symptoms is on the Warning Card your pharmacist gives you. Carry this Warning Card with you at all times. If you stop TRIZIVIR because of an allergic reaction, never take TRIZIVIR (abacavir, lamivudine and zidovudine) or any other abacavir-containing medicine (EPZICOM® , TRIUMEQ®, or ZIAGEN®) again. If you take TRIZIVIR or any other abacavir-containing medicine again after you have had an allergic reaction, within hours you may get life-threatening symptoms that may include very low blood pressure or death. If you stop TRIZIVIR for any other reason, even for a few days, and you are not allergic to TRIZIVIR, talk with your healthcare provider before taking it again. Taking TRIZIVIR again can cause a serious allergic or life-threatening reaction, even if you never had an allergic reaction to it before. If your healthcare provider tells you that you can take TRIZIVIR again, start taking it when you are around medical help or people who can call a healthcare provider if you need one. Blood problems. Zidovudine (RETROVIR®), one of the medicines in TRIZIVIR, can cause serious blood cell problems. These include reduced numbers of white blood cells (neutropenia) and extremely reduced numbers of red blood cells (anemia). These blood cell problems are especially likely to happen in people with advanced human immunodeficiency virus type 1 (HIV-1) disease or AIDS. Your healthcare provider should check your blood cell counts regularly during treatment with TRIZIVIR. Muscle pain or weakness (myopathy) can happen during treatment with TRIZIVIR. Zidovudine (RETROVIR®), one of the medicines in TRIZIVIR, can cause muscle pain or weakness when used for a long time. Build-up of acid in your blood (lactic acidosis). Lactic acidosis can happen in some people who take TRIZIVIR. Lactic acidosis is a serious medical emergency that can cause death. Call your healthcare provider right away if you get any of the following symptoms that could be signs of lactic acidosis: feel very weak or tired feel cold, especially in your arms and legs unusual (not normal) muscle pain feel dizzy or light-headed trouble breathing have a fast or irregular heartbeat stomach pain with nausea and vomiting Serious liver problems can happen in people who take TRIZIVIR. In some cases, these serious liver problems can lead to death. Your liver may become large (hepatomegaly) and you may develop fat in your liver (steatosis). Call your healthcare provider right away if you get any of the following signs or symptoms of liver problems: your skin or the white part of your eyes turns yellow (jaundice) loss of appetite for several days or longer nausea dark or “tea-colored” urine pain, aching, or tenderness on the right side of your stomach area light colored stools (bowel movements) You may be more likely to get lactic acidosis or serious liver problems if you are female, very overweight (obese), or have been taking nucleoside analogue medicines for a long time. Worsening of hepatitis B virus in people who have HIV-1 infection. If you have HIV-1 and hepatitis B virus (HBV) infection, your HBV may get worse (flare-up) if you stop taking TRIZIVIR. A “flare-up” is when your HBV infection suddenly returns in a worse way than before. Worsening liver disease is serious and may lead to death. Do not run out of TRIZIVIR. Refill your prescription or talk to your healthcare provider before your TRIZIVIR is all gone. • Do not stop TRIZIVIR without first talking to your healthcare provider. If you stop taking TRIZIVIR, your healthcare provider will need to check your health often and do blood tests regularly for several months to check your liver. Resistant Hepatitis B Virus (HBV). If you have HIV-1 and hepatitis B, the hepatitis B virus can change (mutate) during your treatment with TRIZIVIR and become harder to treat (resistant). Use with interferon and ribavirin-based regimens. Worsening of liver disease that has caused death has happened in people infected with both HIV-1 and hepatitis C virus who are taking antiretroviral medicines, and are also being treated for hepatitis C with interferon with or without ribavirin. If you are taking TRIZIVIR and interferon with or without ribavirin, tell your healthcare provider if you have any new symptoms. What is TRIZIVIR? TRIZIVIR is a prescription HIV-1 (Human Immunodeficiency Virus type 1) medicine used alone or with other antiretroviral medicines to treat HIV-1 infection. HIV-1 is the virus that causes Acquired Immune Deficiency Syndrome (AIDS). TRIZIVIR contains 3 prescription medicines, abacavir (ZIAGEN®), lamivudine (EPIVIR®) and zidovudine (RETROVIR®). TRIZIVIR should not be used in children weighing less than 88 pounds (40 kg). When used alone or with other antiretroviral medicines to treat HIV-1 infection, TRIZIVIR may help: reduce the amount of HIV-1 in your blood. This is called “viral load”. increase the number of CD4+ (T) cells in your blood, that help fight off other infections. Reducing the amount of HIV-1 and increasing the CD4+ (T) cells in your blood may help improve your immune system. This may reduce your risk of death or getting infections that can happen when your immune system is weak (opportunistic infections). TRIZIVIR does not cure HIV-1 infection or AIDS. You must keep taking HIV-1 medicines to control HIV-1 infection and decrease HIV-related illnesses. Avoid doing things that can spread HIV-1 infection to others. Do not share or re-use needles or other injection equipment. Do not share personal items that can have blood or body fluids on them, like toothbrushes and razor blades. Do not have any kind of sex without protection. Always practice safer sex by using a latex or polyurethane condom to lower the chance of sexual contact with any body fluids such as semen, vaginal secretions, or blood. Ask your healthcare provider if you have any questions about how to prevent passing HIV to other people. Who should not take TRIZIVIR? Do not take TRIZIVIR if you: have a certain type of gene variation called the HLA-B*5701 allele. Your healthcare provider will test you for this before prescribing treatment with TRIZIVIR. are allergic to abacavir or any of the ingredients in TRIZIVIR. See the end of this Medication Guide for a complete list of ingredients in TRIZIVIR. have liver problems. What should I tell my healthcare provider before taking TRIZIVIR? Before you take TRIZIVIR, tell your healthcare provider if you: have been tested and know whether or not you have a particular gene variation called HLA-B*5701. have or have had liver problems, including hepatitis B or C virus infection. have kidney problems. have low blood cell counts (bone marrow problem). Ask your healthcare provider if you are not sure. have heart problems, smoke, or have diseases that increase your risk of heart disease such as high blood pressure, high cholesterol, or diabetes. drink alcohol or take medicines that contain alcohol. are pregnant or plan to become pregnant. It is not known if TRIZIVIR will harm your unborn baby. Talk to your healthcare provider if you are pregnant or plan to become pregnant. Pregnancy Registry. There is a pregnancy registry for women who take antiretroviral medicines during pregnancy. The purpose of this registry is to collect information about the health of you and your baby. Talk to your healthcare provider about how you can take part in this registry. are breastfeeding or plan to breastfeed. Do not breastfeed if you take TRIZIVIR. You should not breastfeed if you have HIV-1 because of the risk of passing HIV-1 to your baby. Tell your healthcare provider about all the medicines you take, including prescription and over-thecounter medicines, vitamins, and herbal supplements. Some medicines interact with TRIZIVIR. Keep a list of your medicines to show your healthcare provider and pharmacist. You can ask your healthcare provider or pharmacist for a list of medicines that interact with TRIZIVIR. Do not start taking a new medicine without telling your healthcare provider. Your healthcare provider can tell you if it is safe to take TRIZIVIR with other medicines. You should not take TRIZIVIR if you also take: abacavir (EPZICOM, TRIUMEQ, or ZIAGEN) lamivudine (COMBIVIR®, DUTREBIS™, EPIVIR®, EPIVIR-HBV®, EPZICOM, or TRIUMEQ) zidovudine (COMBIVIR or RETROVIR) emtricitabine (EMTRIVA®, ATRIPLA®, COMPLERA®, STRIBILD®, or TRUVADA®) Tell your healthcare provider if you take: any other medicine to treat HIV-1 ADRIAMYCIN® (doxorubicin) CYTOVENE® (ganciclovir), interferon alfa, ribavirin, or other bone marrow suppressive medicines or cytotoxic medicines methadone How should I take TRIZIVIR? Take TRIZIVIR exactly as your healthcare provider tells you. Do not change your dose or stop taking TRIZIVIR without talking with your healthcare provider. If you miss a dose of TRIZIVIR, take it as soon as you remember. Do not take 2 doses at the same time. If you are not sure about your dosing, call your healthcare provider. Stay under the care of a healthcare provider while taking TRIZIVIR. TRIZIVIR may be taken with or without food. Tell your healthcare provider if you or your child has trouble swallowing TRIZIVIR tablets. Do not run out of TRZIVIR. The virus in your blood may increase and the virus may become harder to treat. When your supply starts to run low, get more from your healthcare provider or pharmacy. If you take too much TRIZIVIR, call your healthcare provider or go to the nearest hospital emergency room right away. What are the possible side effects of TRIZIVIR? TRIZIVIR can cause serious side effects including: See “What is the most important information I should know about TRIZIVIR?” Changes in your immune system (Immune Reconstitution Syndrome) can happen when you start taking HIV-1 medicines. Your immune system may get stronger and begin to fight infections that have been hidden in your body for a long time. Tell your healthcare provider right away if you start having new symptoms after you start taking TRIZIVIR. Changes in body fat can happen in people who take HIV-1 medicines. These changes may include an increased amount of fat in the upper back and neck (“buffalo hump”), breast, and around the middle of your body (trunk). Loss of fat from the legs, arms, and face may also happen. The exact cause and long-term health effects of these conditions are not known. Heart attack (myocardial infarction). Some HIV-1 medicines including TRIZIVIR may increase your risk of heart attack. The most common side effects of TRIZIVIR include: nausea headache weakness or tiredness vomiting Tell your healthcare provider if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of TRIZIVIR. 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. How should I store TRIZIVIR? Store TRIZIVIR at 59°F to 86°F (15°C to 30°C). Keep TRIZIVIR and all medicines out of the reach of children. General information for safe and effective use of TRIZIVIR. Medicines are sometimes prescribed for purposes other than those listed in a Medication Guide. Do not use TRIZIVIR for a condition for which it was not prescribed. Do not give TRIZIVIR to other people, even if they have the same symptoms that you have. It may harm them. If you would like more information, talk with your healthcare provider. You can ask your healthcare provider or pharmacist for the information about TRIZIVIR that is written for health professionals. For more information go to www.TRIZIVIR.com or call 1-877-844-8872. What are the ingredients in TRIZIVIR? Active ingredients: abacavir, lamivudine, and zidovudine Inactive ingredients: magnesium stearate, microcrystalline cellulose, sodium starch glycolate Tablet film coating contains: OPADRY® green 03B11434 made of FD&C Blue No. 2, hypromellose, polyethylene glycol, titanium dioxide, and yellow iron oxide.

WARNINGS Included as part of the PRECAUTIONS section. PRECAUTIONS Hypersensitivity Reactions Serious and sometimes fatal hypersensitivity reactions have occurred with abacavir, a component of TRIZIVIR. These hypersensitivity reactions have included multi-organ failure and anaphylaxis and typically occurred within the first 6 weeks of treatment with abacavir (median time to onset was 9 days); although abacavir hypersensitivity reactions have occurred any time during treatment [see ADVERSE REACTIONS]. Patients who carry the HLA-B*5701 allele are at a higher risk of abacavir hypersensitivity reactions; although, patients who do not carry the HLA-B*5701 allele have developed hypersensitivity reactions. Hypersensitivity to abacavir was reported in approximately 206 (8%) of 2,670 patients in 9 clinical trials with abacavir-containing products where HLA-B*5701 screening was not performed. The incidence of suspected abacavir hypersensitivity reactions in clinical trials was 1% when subjects carrying the HLA-B*5701 allele were excluded. In any patient treated with abacavir, the clinical diagnosis of hypersensitivity reaction must remain the basis of clinical decision making. Due to the potential for severe, serious, and possibly fatal hypersensitivity reactions with abacavir: All patients should be screened for the HLA-B*5701 allele prior to initiating therapy with TRIZIVIR or reinitiation of therapy with TRIZIVIR, unless patients have a previously documented HLA-B*5701 allele assessment. TRIZIVIR is contraindicated in patients with a prior hypersensitivity reaction to abacavir and in HLA-B*5701-positive patients. Before starting TRIZIVIR, review medical history for prior exposure to any abacavircontaining product. NEVER restart TRIZIVIR or any other abacavir-containing product following a hypersensitivity reaction to abacavir, regardless of HLA-B*5701 status. To reduce the risk of a life-threatening hypersensitivity reaction, regardless of HLA-B*5701 status, discontinue TRIZIVIR immediately if a hypersensitivity reaction is suspected, even when other diagnoses are possible (e.g., acute onset respiratory diseases such as pneumonia, bronchitis, pharyngitis, or influenza; gastroenteritis; or reactions to other medications). If a hypersensitivity reaction cannot be ruled out, do not restart TRIZIVIR or any other abacavir-containing products because more severe symptoms, which may include life-threatening hypotension and death, can occur within hours. If a hypersensitivity reaction is ruled out, patients may restart TRIZIVIR. Rarely, patients who have stopped abacavir for reasons other than symptoms of hypersensitivity have also experienced life-threatening reactions within hours of reinitiating abacavir therapy. Therefore, reintroduction of TRIZIVIR or any other abacavir-containing product is recommended only if medical care can be readily accessed. A Medication Guide and Warning Card that provide information about recognition of abacavir hypersensitivity reactions should be dispensed with each new prescription and refill. Hematologic Toxicity/Bone Marrow Suppression Zidovudine, a component of TRIZIVIR, has been associated with hematologic toxicity including neutropenia and anemia, particularly in patients with advanced HIV-1 disease. TRIZIVIR should be used with caution in patients who have bone marrow compromise evidenced by granulocyte count less than 1,000 cells per mm³ or hemoglobin less than 9.5 grams per dL [see ADVERSE REACTIONS]. Frequent blood counts are strongly recommended in patients with advanced HIV-1 disease who are treated with TRIZIVIR. Periodic blood counts are recommended for other HIV-1-infected patients. If anemia or neutropenia develops, dosage interruption may be needed. Myopathy Myopathy and myositis, with pathological changes similar to that produced by HIV-1 disease, have been associated with prolonged use of zidovudine, and therefore may occur with therapy with TRIZIVIR. Lactic Acidosis And Severe Hepatomegaly With Steatosis Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogues and other antiretrovirals. See full prescribing information for ZIAGEN® (abacavir), EPIVIR® (lamivudine), and RETROVIR® (zidovudine). Treatment with TRIZIVIR should be suspended in any patient who develops clinical or laboratory findings suggestive of lactic acidosis or pronounced hepatotoxicity (which may include hepatomegaly and steatosis even in the absence of marked transaminase elevations). Patients With Hepatitis B Virus Co-infection Posttreatment Exacerbations of Hepatitis Clinical and laboratory evidence of exacerbations of hepatitis have occurred after discontinuation of lamivudine. See full prescribing information for EPIVIR (lamivudine). Patients should be closely monitored with both clinical and laboratory follow-up for at least several months after stopping treatment. Emergence of Lamivudine-resistant HBV Safety and efficacy of lamivudine have not been established for treatment of chronic hepatitis B in subjects dually infected with HIV-1 and HBV. Emergence of hepatitis B virus variants associated with resistance to lamivudine has been reported in HIV–1-infected subjects who have received lamivudine-containing antiretroviral regimens in the presence of concurrent infection with hepatitis B virus. See full prescribing information for EPIVIR (lamivudine). Use With Interferon-And Ribavirin-Based Regimens Patients receiving interferon alfa with or without ribavirin and TRIZIVIR should be closely monitored for treatment-associated toxicities, especially hepatic decompensation, neutropenia, and anemia. See full prescribing information for EPIVIR (lamivudine) and RETROVIR (zidovudine). Discontinuation of TRIZIVIR should be considered as medically appropriate. Dose reduction or discontinuation of interferon alfa, ribavirin, or both should also be considered if worsening clinical toxicities are observed, including hepatic decompensation (e.g., Child-Pugh greater than 6) (see full prescribing information for interferon and ribavirin). Exacerbation of anemia has been reported in HIV-1/HCV co-infected patients receiving ribavirin and zidovudine. Coadministration of ribavirin and TRIZIVIR is not advised. Immune Reconstitution Syndrome Immune reconstitution syndrome has been reported in patients treated with combination antiretroviral therapy, including TRIZIVIR. During the initial phase of combination antiretroviral treatment, patients whose immune systems respond may develop an inflammatory response to indolent or residual opportunistic infections (such as Mycobacterium avium infection, cytomegalovirus, Pneumocystis jirovecii pneumonia [PCP], or tuberculosis), which may necessitate further evaluation and treatment. Autoimmune disorders (such as Graves' disease, polymyositis, and Guillain-Barré syndrome) have also been reported to occur in the setting of immune reconstitution; however, the time to onset is more variable, and can occur many months after initiation of treatment. Fat Redistribution Redistribution/accumulation of body fat including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and “cushingoid appearance” have been observed in patients receiving antiretroviral therapy. The mechanism and long-term consequences of these events are currently unknown. A causal relationship has not been established. Myocardial Infarction In a published prospective, observational, epidemiological trial designed to investigate the rate of myocardial infarction (MI) in patients on combination antiretroviral therapy, the use of abacavir within the previous 6 months was correlated with an increased risk of MI. In a sponsor-conducted pooled analysis of clinical trials, no excess risk of MI was observed in abacavir-treated subjects as compared with control subjects. In totality, the available data from the observational cohort and from clinical trials are inconclusive. As a precaution, the underlying risk of coronary heart disease should be considered when prescribing antiretroviral therapies, including abacavir, and action taken to minimize all modifiable risk factors (e.g., hypertension, hyperlipidemia, diabetes mellitus, smoking). Therapy-Experienced Patients In clinical trials, subjects with prolonged prior nucleoside reverse transcriptase inhibitor (NRTI) exposure or who had HIV-1 isolates that contained multiple mutations conferring resistance to NRTIs had limited response to abacavir. The potential for cross-resistance between abacavir and other NRTIs should be considered when choosing new therapeutic regimens in therapy-experienced patients [see Microbiology]. Related Products That Are Not Recommended TRIZIVIR is a fixed-dose combination of 3 nucleoside analogue reverse transcriptase inhibitors (abacavir, lamivudine, and zidovudine). Concomitant administration of TRIZIVIR with other products containing abacavir, lamivudine, or zidovudine is not recommended. In addition, do not administer TRIZIVIR in combination with products containing emtricitabine. Patient Counseling Information Advise the patient to read the FDA-approved patient labeling (Medication Guide). Hypersensitivity Reaction Inform patients that a Medication Guide and Warning Card summarizing the symptoms of the abacavir hypersensitivity reaction and other product information will be dispensed by the pharmacist with each new prescription and refill of TRIZIVIR, and instruct the patient to read the Medication Guide and Warning Card every time to obtain any new information that may be present about TRIZIVIR. The complete text of the Medication Guide is reprinted at the end of this document. to carry the Warning Card with them. how to identify a hypersensitivity reaction [see WARNINGS AND PRECAUTIONS, Medication Guide]. that if they develop symptoms consistent with a hypersensitivity reaction they should call their healthcare provider right away to determine if they should stop taking TRIZIVIR. that a hypersensitivity reaction can worsen and lead to hospitalization or death if TRIZIVIR is not immediately discontinued. to not restart TRIZIVIR or any other abacavir-containing product following a hypersensitivity reaction because more severe symptoms can occur within hours and may include life-threatening hypotension and death. that a hypersensitivity reaction is usually reversible if it is detected promptly and TRIZIVIR is stopped right away. that if they have interrupted TRIZIVIR for reasons other than symptoms of hypersensitivity (for example, those who have an interruption in drug supply), a serious or fatal hypersensitivity reaction may occur with reintroduction of abacavir. to not restart TRIZIVIR or any other abacavir-containing product without medical consultation and only if medical care can be readily accessed by the patient or others. Related Products that are Not Recommended Inform patients that they should not take TRIZIVIR with ATRIPLA®, COMBIVIR, COMPLERA®, DUTREBIS™, EMTRIVA®, EPIVIR, EPIVIR-HBV®, EPZICOM® , RETROVIR, STRIBILD®, TRIUMEQ®, TRUVADA®, or ZIAGEN. Neutropenia and Anemia Inform patients that the important toxicities associated with zidovudine are neutropenia and/or anemia. Inform them of the extreme importance of having their blood counts followed closely while on therapy, especially for patients with advanced HIV-1 disease [see BOXED WARNING, WARNINGS AND PRECAUTIONS]. Myopathy Inform patients that myopathy and myositis with pathological changes, similar to that produced by HIV-1 disease, have been associated with prolonged use of zidovudine [see WARNINGS AND PRECAUTIONS]. Lactic Acidosis/Hepatomegaly Inform patients that some HIV medicines, including TRIZIVIR, can cause a rare, but serious condition called lactic acidosis with liver enlargement (hepatomegaly) [see WARNINGS AND PRECAUTIONS]. Patients with Hepatitis B or C Co-infection Advise patients co-infected with HIV-1 and HBV that worsening of liver disease has occurred in some cases when treatment with lamivudine was discontinued. Advise patients to discuss any changes in regimen with their physician [see WARNINGS AND PRECAUTIONS]. Inform patients with HIV-1/HCV co-infection that hepatic decompensation (some fatal) has occurred in HIV-1/HCV co-infected patients receiving combination antiretroviral therapy for HIV-1 and interferon alfa with or without ribavirin [see WARNINGS AND PRECAUTIONS]. Immune Reconstitution Syndrome In some patients with advanced HIV infection, signs and symptoms of inflammation from previous infections may occur soon after anti-HIV treatment is started. It is believed that these symptoms are due to an improvement in the body's immune response, enabling the body to fight infections that may have been present with no obvious symptoms. Advise patients to inform their healthcare provider immediately of any symptoms of infection [see WARNINGS AND PRECAUTIONS]. Redistribution/Accumulation of Body Fat Inform patients that redistribution or accumulation of body fat may occur in patients receiving antiretroviral therapy and that the cause and long-term health effects of these conditions are not known at this time [see WARNINGS AND PRECAUTIONS]. Information about HIV-1 Infection TRIZIVIR is not a cure for HIV-1 infection and patients may continue to experience illnesses associated with HIV-1 infection, including opportunistic infections. Patients must remain on continuous HIV therapy to control HIV-1 infection and decrease HIV-related illness. Inform patients that sustained decreases in plasma HIV RNA have been associated with a reduced risk of progression to AIDS and death. Advise patients to remain under the care of a physician when using TRIZIVIR. Advise patients to take all HIV medications exactly as prescribed. Advise patients to avoid doing things that can spread HIV-1 infection to others. Advise patients not to re-use or share needles or other injection equipment. Advise patients not to share personal items that can have blood or body fluids on them, like toothbrushes and razor blades. Advise patients to always practice safer sex by using a latex or polyurethane condom to lower the chance of sexual contact with semen, vaginal secretions, or blood. Female patients should be advised not to breastfeed. Mothers with HIV-1 should not breastfeed because HIV-1 can be passed to the baby in the breast milk. Instruct patients that if they miss a dose, they should take it as soon as they remember. If they do not remember until it is time for the next dose, they should be instructed to skip the missed dose and go back to the regular schedule. Patients should not double their next dose or take more than the prescribed dose. Instruct patients to read the Medication Guide before starting TRIZIVIR and to reread it each time the prescription is renewed. Instruct patients to inform their physician or pharmacist if they develop any unusual symptom, or if any known symptom persists or worsens. Nonclinical Toxicology Carcinogenesis, Mutagenesis, Impairment Of Fertility Carcinogenicity Abacavir: Abacavir was administered orally at 3 dosage levels to separate groups of mice and rats in 2-year carcinogenicity studies. Results showed an increase in the incidence of malignant and non-malignant tumors. Malignant tumors occurred in the preputial gland of males and the clitoral gland of females of both species, and in the liver of female rats. In addition, non-malignant tumors also occurred in the liver and thyroid gland of female rats. These observations were made at systemic exposures in the range of 6 to 32 times the human exposure at the recommended dose of 600 mg. Lamivudine: Long-term carcinogenicity studies with lamivudine in mice and rats showed no evidence of carcinogenic potential at exposures up to 10 times (mice) and 58 times (rats) the human exposures at the recommended dose of 300 mg. Zidovudine: Zidovudine was administered orally at 3 dosage levels to separate groups of mice and rats (60 females and 60 males in each group). Initial single daily doses were 30, 60, and 120 mg per kg per day in mice and 80, 220, and 600 mg per kg per day in rats. The doses in mice were reduced to 20, 30, and 40 mg per kg per day after day 90 because of treatment-related anemia, whereas in rats only the high dose was reduced to 450 mg per kg per day on day 91 and then to 300 mg per kg per day on day 279. In mice, 7 late-appearing (after 19 months) vaginal neoplasms (5 nonmetastasizing squamous cell carcinomas, 1 squamous cell papilloma, and 1 squamous polyp) occurred in animals given the highest dose. One late-appearing squamous cell papilloma occurred in the vagina of a middle-dose animal. No vaginal tumors were found at the lowest dose. In rats, 2 late-appearing (after 20 months), nonmetastasizing vaginal squamous cell carcinomas occurred in animals given the highest dose. No vaginal tumors occurred at the low or middle dose in rats. No other drug-related tumors were observed in either sex of either species. At doses that produced tumors in mice and rats, the estimated drug exposure (as measured by AUC) was approximately 3 times (mouse) and 24 times (rat) the estimated human exposure at the recommended therapeutic dose of 100 mg every 4 hours. It is not known how predictive the results of rodent carcinogenicity studies may be for humans. Two transplacental carcinogenicity studies were conducted in mice. One study administered zidovudine at doses of 20 mg per kg per day or 40 mg per kg per day from gestation day 10 through parturition and lactation with dosing continuing in offspring for 24 months postnatally. At these doses, exposures were approximately 3 times the estimated human exposure at the recommended doses. After 24 months at the 40-mg per kg per day dose, an increase in incidence of vaginal tumors was noted with no increase in tumors in the liver or lung or any other organ in either gender. These findings are consistent with results of the standard oral carcinogenicity study in mice, as described earlier. A second study administered zidovudine at maximum tolerated doses of 12.5 mg per day or 25 mg per day (approximately 1,000 mg per kg nonpregnant body weight or approximately 450 mg per kg of term body weight) to pregnant mice from days 12 through 18 of gestation. There was an increase in the number of tumors in the lung, liver, and female reproductive tracts in the offspring of mice receiving the higher dose level of zidovudine. Mutagenicity Abacavir: Abacavir induced chromosomal aberrations both in the presence and absence of metabolic activation in an in vitro cytogenetic study in human lymphocytes. Abacavir was mutagenic in the absence of metabolic activation, although it was not mutagenic in the presence of metabolic activation in an L5178Y mouse lymphoma assay. Abacavir was clastogenic in males and not clastogenic in females in an in vivo mouse bone marrow micronucleus assay. Abacavir was not mutagenic in bacterial mutagenicity assays in the presence and absence of metabolic activation. Lamivudine: Lamivudine was mutagenic in an L5178Y mouse lymphoma assay and clastogenic in a cytogenetic assay using cultured human lymphocytes. Lamivudine was not mutagenic in a microbial mutagenicity assay, in an in vitro cell transformation assay, in a rat micronucleus test, in a rat bone marrow cytogenetic assay, and in an assay for unscheduled DNA synthesis in rat liver. Zidovudine: Zidovudine was mutagenic in an L5178Y mouse lymphoma assay, positive in an in vitro cell transformation assay, clastogenic in a cytogenetic assay using cultured human lymphocytes, and positive in mouse and rat micronucleus tests after repeated doses. It was negative in a cytogenetic study in rats given a single dose. Impairment of Fertility Abacavir or Lamivudine: Abacavir or lamivudine did not affect male or female fertility in rats at a dose associated with exposures approximately 8 or 130 times, respectively, higher than the exposures in humans at the doses of 600 mg and 300 mg (respectively). Zidovudine: Zidovudine, administered to male and female rats at doses up to 7 times the usual adult dose based on body surface area considerations, had no effect on fertility judged by conception rates. Use In Specific Populations Pregnancy Pregnancy Category C There are no adequate and well-controlled studies of TRIZIVIR in pregnant women. Reproduction studies with abacavir, lamivudine, and zidovudine have been performed in animals (see Abacavir, Lamivudine, and Zidovudine sections below). TRIZIVIR should be used during pregnancy only if the potential benefits outweigh the risks. Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to TRIZIVIR during pregnancy. Physicians are encouraged to register patients by calling the Antiretroviral Pregnancy Registry at 1-800-258-4263. Abacavir Studies in pregnant rats showed that abacavir is transferred to the fetus through the placenta. Fetal malformations (increased incidences of fetal anasarca and skeletal malformations) and developmental toxicity (depressed fetal body weight and reduced crown-rump length) were observed in rats at a dose which produced 35 times the human exposure, based on AUC. Embryonic and fetal toxicities (increased resorptions, decreased fetal body weights) and toxicities to the offspring (increased incidence of stillbirth and lower body weights) occurred at half of the above-mentioned dose in separate fertility studies conducted in rats. In the rabbit, no developmental toxicity and no increases in fetal malformations occurred at doses that produced 8.5 times the human exposure at the recommended dose based on AUC. Lamivudine Studies in pregnant rats showed that lamivudine is transferred to the fetus through the placenta. Reproduction studies with orally administered lamivudine have been performed in rats and rabbits at doses producing plasma levels up to approximately 35 times that for the recommended adult HIV dose. No evidence of teratogenicity due to lamivudine was observed. Evidence of early embryolethality was seen in the rabbit at exposure levels similar to those observed in humans, but there was no indication of this effect in the rat at exposure levels up to 35 times those in humans. Zidovudine Reproduction studies with orally administered zidovudine in the rat and in the rabbit at doses up to 500 mg per kg per day revealed no evidence of teratogenicity with zidovudine. Zidovudine treatment resulted in embryo/fetal toxicity as evidenced by an increase in the incidence of fetal resorptions in rats given 150 or 450 mg per kg per day and rabbits given 500 mg per kg per day. The doses used in the teratology studies resulted in peak zidovudine plasma concentrations (after one-half of the daily dose) in rats 66 to 226 times, and in rabbits 12 to 87 times, mean steady-state peak human plasma concentrations (after one-sixth of the daily dose) achieved with the recommended daily dose (100 mg every 4 hours). In an additional teratology study in rats, a dose of 3,000 mg per kg per day (very near the oral median lethal dose in rats of approximately 3,700 mg per kg) caused marked maternal toxicity and an increase in the incidence of fetal malformations. This dose resulted in peak zidovudine plasma concentrations 350 times peak human plasma concentrations. No evidence of teratogenicity was seen in this experiment at doses of 600 mg per kg per day or less. Two rodent carcinogenicity studies were conducted [see Nonclinical Toxicology]. Lactation The Centers for Disease Control and Prevention recommend that HIV-1-infected mothers in the United States not breastfeed their infants to avoid risking postnatal transmission of HIV-1 infection. Because of the potential for HIV-1 transmission mothers should be instructed not to breastfeed. Pediatric Use TRIZIVIR is not recommended in children who weigh less than 40 kg because it is a fixed-dose tablet that cannot be adjusted for these patient populations [see DOSAGE AND ADMINISTRATION]. Therapy-Experienced Pediatric Trial A randomized, double-blind trial, CNA3006, compared ZIAGEN plus lamivudine and zidovudine versus lamivudine and zidovudine in pediatric subjects, most of whom were extensively pretreated with nucleoside analogue antiretroviral agents. Subjects in this trial had a limited response to abacavir. Geriatric Use Clinical trials of abacavir, lamivudine, and zidovudine did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, caution should be exercised in the administration of TRIZIVIR in elderly patients reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy [see CLINICAL PHARMACOLOGY]. Patients With Impaired Renal Function TRIZIVIR is not recommended for patients with creatinine clearance less than 50 mL per min because TRIZIVIR is a fixed-dose combination and the dosage of the individual components cannot be adjusted. If a dose reduction of the lamivudine or zidovudine components of TRIZIVIR is required for patients with renal impairment then the individual components should be used [see DOSAGE AND ADMINISTRATION, CLINICAL PHARMACOLOGY]. Patients With Impaired Hepatic Function TRIZIVIR is a fixed-dose combination and the dosage of the individual components cannot be adjusted. If a dose reduction of abacavir, a component of TRIZIVIR, is required for patients with mild hepatic impairment (Child-Pugh Class A), then the individual components should be used [see CLINICAL PHARMACOLOGY]. The safety, efficacy, and pharmacokinetic properties of abacavir have not been established in patients with moderate (Child-Pugh Class B) or severe (Child-Pugh Class C) hepatic impairment; therefore, TRIZIVIR is contraindicated in these patients [see CONTRAINDICATIONS]. Zidovudine is primarily eliminated by hepatic metabolism and zidovudine concentrations are increased in patients with impaired hepatic function, which may increase the risk of hematologic toxicity. Frequent monitoring of hematologic toxicities is advised.