Genital herpes simplex virus infection is associated with frequent symptomatic recurrences. These recurrences are often painful and pruritic, and may be psychologically disturbing. Various antiviral agents, including famciclovir, are approved for treatment of acute recurrences of genital herpes. However, episodic treatment may not be sufficient in patients with frequent recurrences. Diaz-Mitoma and associates conducted a randomized, double-blind, placebo-controlled trial to assess the safety and efficacy of famciclovir given for suppression of genital herpes simplex virus recurrences.

Adults with a history of recurrent genital herpes were recruited from 30 centers in Canada and Europe. Patients who had not been treated with acyclovir in the 12 months before the study were required to have had at least six recurrences in the preceding year; patients who had been treated with acyclovir were included in the study if they had had at least six recurrences during a 12-month period in the preceding two years.

Patients were randomized to receive either placebo or one of three doses of famciclovir: 125 mg three times daily, 250 mg two times daily or 250 mg three times daily. The treatment lasted for one year. After a few recurrences, patients were given the option of taking 250 mg of open-label famciclovir three times daily. Information about side effects and recurrence of lesions was collected.

A total of 455 patients were available for analysis. About one half of these patients had received acyclovir on an episodic basis for genital herpes. Fifty-five percent of patients in the placebo group withdrew from the study because of lack of efficacy, compared with 16 percent who withdrew from the treatment groups. Patients who received the active drug had a significantly longer time until first recurrence than those receiving placebo. The groups receiving dosages of 250 mg two or three times daily had first recurrences more than 10 months after beginning the study, compared with seven months in the lowest-dose famciclovir group and about seven weeks in those receiving placebo. More patients in the famciclovir groups remained free of recurrences than those in the placebo group. This difference continued throughout the 52 weeks of treatment, with about three times more patients in the famciclovir groups remaining free of recurrence than patients in the placebo group.

The authors conclude that suppression of genital herpes simplex virus recurrences is conveniently, safely and effectively achieved by taking 250 mg of famciclovir twice daily. This dosage is associated with a median recurrence-free period of 11 months and with 80 percent fewer recurrences than placebo.