Acyclovir in the treatment of simian varicella virus infection of the African green monkey.

Acyclovir (9-(2-hydroxyethoxymethyl)guanine) administered as an intramuscular formulation twice daily at a dosage of 100 mg/kg per day prevented the development of disease in African green monkeys inoculated with simian varicella virus. Viremia, appearance of a vesicular rash, and elevations of serum transaminases, each indicative of infection, were suppressed by acyclovir treatment. Plasma concentrations of acyclovir were measured and showed rising levels after repeated intramuscular injection with a prolonged period of absorption of acyclovir into the plasma circulation. Investigation of antiviral efficacy after either intramuscular or intravenous acyclovir treatment showed both routes of administration to be effective in inhibiting simian varicella virus infection at the 100 mg/kg per day level. However, intravenous acyclovir 50 mg/kg twice daily did result in elevated values of blood urea nitrogen, creatinine, and serum transaminases.