Ineffectiveness of topical adenine arabinoside 5'-monophosphate in the treatment of recurrent herpes simplex labialis.

The ability of topical 10 per cent adenine arabinoside 5'-monophosphate to decrease the severity and frequency of recurrent herpes simplex labialis was evaluated in a double-blind, randomized study of 233 patients at three collaborating institutions. Nine clinical and four virologic measurements were used to evaluate drug efficacy during a single episode. No statistically significant improvement in any measurement was seen in the drug-treated patients. Analyses according to institution and age, stage and size of lesion before therapy also indicated no benefit attributable to the drug. There was no effect of the drug on the rate of recurrence of herpes simplex labialis. We conclude that, despite activity against herpes simplex virus infection in tissue culture and in some laboratory animal models, topical use of the drug is ineffective against recurrent herpes simplex labialis. This may be due to failure of the drug to penetrate the skin.