Objective: A randomized, double-blind trial at seven ski sites in Canada and the United States was conducted to compare the effectiveness and the patient tolerance of topically applied 5% acyclovir cream (MAC III formulation) with those of a placebo cream in the prevention of sun-induced herpes labialis lesions.
Study design: All subjects had experienced more than three episodes of sun-induced herpes labialis during the previous year. There were 196 subjects enrolled; 5 did not receive medication, and 10 were excluded from the efficacy analysis for protocol violations. There were 191 subjects in the intent-to-treat analysis, and a separate efficacy analysis was done on 181 subjects. Log rank and Fisher exact tests were used in the analysis.
Results: There was no difference between the two groups at baseline with respect to any clinical or demographic factor. There was no substantial difference between the groups with respect to adverse experiences (15 for acyclovir; 13 for the placebo). The acyclovir group had significantly fewer lesions (p < 0.01) than the placebo group (21% vs. 40%) during the 4-day follow-up period.
Conclusion: The acyclovir group was significantly better than the placebo group during the follow-up period. The safety record of the drug was satisfactory; there was no difference between acyclovir and the placebo in side effects or pain. Topically applied 5% acyclovir cream is an effective preventive step for those who are active and exposed to the sun.