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CLINICAL PHARMACOLOGY Mechanism of Action The oral poliovirus vaccine stimulates the immune system to produce anti-poliovirus antibodies against Sabin poliovirus types 1, 2, and 3. The live virus persists in the gastrointestinal tract for 4-6 weeks, inducing both mucosal and serum anti-poliovirus antibodies capable of opsonization, neutralization, and complement activation. It is likely that reinfection with naturally occurring poliovirus or vaccine strains reinforces OPV-induced humoral immunity. Pharmacokinetics Antibody stimulation after oral administration of OPV occurs within 7-10 days and peaks at approximately 3 weeks. Poliovirus antibodies are distributed into breast milk. It is unknown if poliovirus antibodies cross the placenta (see CONTRAINDICATIONS). Most individuals are protected after one dose, and the majority of vaccinees are protected after two doses. The duration of immunity is not known, but studies in children have revealed that 95% of vaccinees have protective antibodies to all three virus types 5 years after vaccination. Several studies suggest that intestinal resistance can persist for 6 years after vaccination.

DESCRIPTION Oral poliovirus vaccine (OPV) contains live attenuated poliovirus (Sabin strain types 1, 2 and 3) and is intended for polio prophylaxis in infants 6-12 weeks of age, all unimmunized children up to 18 years of age, and high-risk adults. Adults, however, should receive the inactivated poliovirus vaccine (IPV). The attenuated virus particles in OPV are harvested from monkey kidney cell cultures and undergo an extensive purification process. OPV is administered multiple times to ensure immunity to all three types of poliovirus. Clinical studies reveal that OPV is highly effective in preventing natural poliovirus-induced neurologic sequelae. OPV received FDA approval in1963.

INDICATIONS For poliovirus prophylaxis: Adults: 0.5 mL PO initially, then repeated 8 weeks later. The third dose should be given 8-12 months after the second dose. When less than 4 weeks is available before immunization is required, a single 0.5 ml PO dose should be given. Infants: The first 0.5 ml PO dose should be administered at 6-12 weeks of age. The second 0.5 ml PO dose should be administered preferably 8 weeks after the first dose. The third 0.5 ml PO dose should be administered at 6 months of age, however, if this time cannot be met, the third dose may be administered as late as 18 months of age. Children up to age 18 years: 0.5 mL PO initially, followed by the second dose preferably 8 weeks after the first dose. The third dose is given 8-12 months after the second dose (adolescents and older children may receive the third dose 6-8 weeks after the second dose if there is an increased risk of poliomyelitis). Booster doses are suggested upon starting school at 4-6 years of age, unless the third dose of the primary series was given after the recipient's fourth birthday. Patients with renal impairment: Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed. DOSAGE AND ADMINISTRATION Administration Poliovirus vaccine live oral, OPV is administered orally. OPV must not be administered parenterally. May be administered directly into the mouth using the single-dose pipette supplied by the manufacturer. Alternatively, mix with distilled or chlorine-free water, syrup, or milk, or adsorbed on bread, cake, or sugar cube. If a dose is not swallowed, spat out, or a substantial portion is regurgitated or vomited shortly after administration (i.e., within 5-10 minutes), a second dose should be given. If the second dose is not retained, do not count either dose, readminister on the next visit. HOW SUPPLIED No Information Provided

PATIENT INFORMATION See PRECAUTIONS and CONTRAINDICATIONS.

OVERDOSE No Information Provided CONTRAINDICATIONS The poliovirus vaccine should be used with caution in patients with a history of neomycin hypersensitivity or streptomycin hypersensitivity because these agents may be used in the preparation of OPV. A history of delayed-type allergic reactions is not an absolute contraindication to OPV administration.

WARNINGS No information provided. PRECAUTIONS OPV may not be as immunogenic in elderly patients or in patients suffering from immunosuppression (congenital, acquired, or iatrogenic). Furthermore, virus particle production can be potentiated in immunosuppressed patients, so OPV use is not recommended in these individuals. Patients with HIV infection may receive IPV or enhanced-potency IPV; however, OPV should be avoided. Patients with evidence of viral infection (diarrhea, vomiting) should not be given OPV because other enteroviruses within the intestinal tract can inhibit immunity by preventing OPV replication. Similarly, OPV inoculation should be postponed in patients with fever or a severe respiratory infection, although minor illness does not preclude OPV administration. Intramuscular injections, especially antibiotics, should be avoided for at least 30 days in patients who have received the poliovirus vaccine live oral (OPV) or for 60 days in patients who acquired the disease by contact with vaccine recipients. Intramuscular injections were associated with an increased risk of developing paralytic poliomyelitis in patients receiving IM injections 30 days prior to the onset of paralysis. OPV is classified as pregnancy category C. Studies in humans have not been conducted. Problems in humans have not been reported, but routine administration of OPV during pregnancy is not recommended unless the benefits from vaccination outweigh the potential risks to the fetus. Poliovirus antibodies may be excreted into breast milk, and breast-feeding is not recommended for 2-3 hours before or after inoculation in neonates immunized at birth. Use of OPV is not recommended in neonates less than 6 weeks of age. Poliomyelitis has occurred after OPV administration both in vaccinees and in their close contacts. Poliovirus may be shed in the feces (and possibly from the pharynx) of vaccinees for 6-8 weeks after OPV administration. Contact individuals should be warned of the small risk of developing poliomyelitis and informed to wash hands carefully when exposed to feces or saliva of recently inoculated vaccinees.