Tablet, 200mg, 400mg
Powder for injection, 250mg, 500mg in vial
Indications: - viral infections due to herpes simplex virus (types 1 and 2) and varicella-zoster virus (herpes zoster and chickenpox); see also under dose.
Cautions: - renal impairment (dose should be adjusted), rapid or bolus injection should be avoided and adequate hydration maintained; pregnancy and breast-feeding; see also interaction.
Drug interactions: - probenecid, any nephrotoxic drugs.
Side effects: - nausea, vomiting abdominal pain, diarrhea, headache, fatigue, rash urticaria, pruritus, photosensitivity; rarely hepatitis, jaundice, dyspnoea, angioedema, anaphylaxis, neurological reactions (including dizziness, confusion, hallucinations and drowsiness), acute renal failure, decreases in hematological indices; on intravenous infusion, severe local inflammation (sometimes leading to ulceration), fever, and rarely agitation, tremors, psychosis and convulsions.
Dose and Administration:
Herpes simplex, treatment, 200mg (400mg in the immunocompromised or if absorption impaired) 5 times daily, usually for 5 days; CHILD under 2 years, half adult dose, over 2 years, adult dose.
Herpes simplex, prevention of recurrence, 200mg 4 times daily or 400mg twice daily possibly reduced to 200mg 2 or 3 times daily and interrupted every 6-12 months.
Herpes simplex, prophylaxis in the immunocompromised, 200-400mg 4 times daily; CHILD under 2 years, half adult dose; over 2 years, adult dose
Varicella and herpes zoster, treatment, 800mg 5 times daily for 7 days; CHILD, varicella, 20mg/kg (max. 800mg) 4 times daily for 5 days or under 2 years 200mg 4 times daily, 2-5 years 400mg 4 times daily, over 6 years 800mg 4 times daily.
Intravenous infusion, treatment of herpes simplex in the immunocompromised, severe initial genital herpes, and varicella-zoster, 5mg/kg every 8 hours usually for 5 days, doubled to 10mg/kg every 8 hours usually in varicella-zoster in the immunocompromised and in simplex encephalitis (usually given for 10 days in encephalitis); prophylaxis of herpes simplex in the immunocopromised, 5mg/kg every 8 hours. NEONATE up to 3 months, herpes simplex, 10mg/kg every 8 hours usually for 10 days; CHILD 3 months-12 years, herpes simplex or varicella-zoster in immunocompromised and in simplex encephalitis (usually given for 10 days in encephalitis)