Peginterferon alfa

eMC §4.2 (Pegasys, peginterferon alfa-2a, 135 micrograms solution for injection in pre-filled syringe). Treatment should be initiated only by a physician experienced in treating polycythaemia vera, essential thrombocythaemia, or hepatitis B or C. CHRONIC HEPATITIS B (adults): 180 micrograms once weekly for 48 weeks, for both HBeAg-positive and HBeAg-negative disease. CHRONIC HEPATITIS C (treatment-naive adults): 180 micrograms once weekly in combination with oral ribavirin, or as monotherapy (monotherapy should only be considered where other medicinal products are contraindicated); ribavirin dose per SPC Table 1 is 1 000 mg daily if under 75 kg and 1 200 mg daily if 75 kg or more for genotypes 1 and 4, and 800 mg daily for genotypes 2 and 3, taken with food. Duration depends on genotype and rapid viral response: genotype 1 high viral load with RVR, or genotype 1/4 without RVR = 48 weeks; genotype 1 low viral load with RVR or genotype 4 with RVR = 24 or 48 weeks; genotype 2 or 3 = 24 weeks (16 weeks may be considered in selected low-viral-load patients HCV-negative by week 4, but carries a higher relapse risk); genotypes 5 or 6 = combination with ribavirin 1 000/1 200 mg for 48 weeks. Recommended duration of Pegasys MONOTHERAPY is 48 weeks. TREATMENT-EXPERIENCED adults: 180 micrograms once weekly subcutaneously with ribavirin 1 000 mg daily if under 75 kg or 1 200 mg daily if 75 kg or more, regardless of genotype. POLYCYTHAEMIA VERA / ESSENTIAL THROMBOCYTHAEMIA (adults): titrate individually starting at 45 micrograms once weekly subcutaneously, increasing gradually by 45 micrograms monthly until haematological parameters stabilise (polycythaemia vera: haematocrit under 45% without phlebotomy, platelets 400x10^9/L or less, leukocytes under 10x10^9/L; essential thrombocythaemia: platelets 400x10^9/L or less and leukocytes under 10x10^9/L); the dose may be adapted and/or the administration interval prolonged as appropriate. If adverse reactions develop, reduce the dose or discontinue temporarily until they abate, then re-initiate at a lower dose than the one that caused them. PAEDIATRIC: the eMC §4.3 contraindicates use in neonates and young children up to 3 years old (benzyl alcohol excipient) and in paediatric patients with present or past severe psychiatric conditions. The US labelling doses children by body surface area, not by weight: 180 micrograms/1.73 m2 x BSA subcutaneously once weekly to a maximum of 180 micrograms (CHC 5-17 years, in combination with ribavirin, 24 weeks for genotype 2 or 3 and 48 weeks for other genotypes; HBeAg-positive CHB 3-17 years for 48 weeks), and patients who start before their 18th birthday should stay on the paediatric dosage through completion of therapy. Because this is a BSA-based and not a per-kg regimen it has not been entered as a structured paediatric dose - verify any under-18 use against a children's formulary. NOTE: the eMC §4.2 text captured in this bundle is truncated part-way through the treatment-experienced section, so dose-modification tables (for neutropenia, thrombocytopenia, ALT elevation, depression and renal impairment) were not retrieved - clinician to review the full SPC.