Therapeutic effects of foscarnet sodium and acyclovir on cutaneous infections due to herpes simplex virus type 1 in guinea pigs.

The therapeutic effects of topically applied foscarnet sodium and acyclovir on cutaneous infections due to herpes simplex virus type 1 (HSV-1) were studied in guinea pigs. Foscarnet cream (3%) reduced both the cumulative vesicle score and the time for healing when HSV-1 strains C42 and 79 were tested. The application of foscarnet in cream form resulted in a dose-dependent reduction in skin virus titers and vesicle scores at concentrations ranging from 0.05% to 3%. Infections due to HSV-1 strain 79, but not those due to strain C42, were sensitive to treatment with 5% acyclovir in polyethylene glycol ointment. Topical application of 3% acyclovir in dimethyl sulfoxide on infections due to HSV-1 strain C42 resulted in a reduction in the skin virus titers, lesion scores, and the time for healing. Acyclovir, in both polyethylene glycol and dimethyl sulfoxide, was consistently less active than foscarnet cream in these animal experiments.