Evaluation of the antiherpetic activity of acyclovir in rabbits.

Acyclovir (3 percent ointment) used topically one to five times a day on acute ocular herpes simplex virus (HSV) infection gave beneficial results as measured by a reduction in corneal involvement, conjunctivitis, iritis, and corneal clouding. Early intensive acyclovir topical treatment every two hours beginning 24 hours after inoculation prevented all but conjunctivitis. Topical treatments did not prevent the establishment of latent HSV infection. Effects of topical acyclovir treatment on rabbit eyes infected with parent McKrae, idoxuridine-resistant, and vidarabine-resistant strains of HSV-1 were studied. Topical acyclovir therapy given four times a day was significantly more effective than idoxuridine and vidarabine in suppressing acute herpetic ocular disease induced by either sensitive or drug-resistant strains of HSV-1. Virus isolation from neural tissues indicated that none of the therapy prevented viral infection in the nervous system. Intravenous acyclovir used twice a day (50 mg/kg) on rabbits with latent HSV infection appeared to suppress HSV in the nervous system but did not eradicate established latent HSV infection.