Acyclovir vs isoprinosine (immunovir) for suppression of recurrent genital herpes simplex infection.

OBJECTIVE To compare the efficacy and safety of oral acyclovir (400 mg twice daily) with oral isoprinosine (500 mg twice daily) in the suppression of recurrent genital herpes. DESIGN Double-blind, double-dummy, randomised, controlled, parallel group trial. SETTING 13 centres in UK, Belgium and Germany. SUBJECTS 127 immunocompetent patients with frequently recurring genital herpes. MAIN OUTCOME MEASURES Proportions of patients reporting recurrences, recurrence frequency, and mean duration of lesions during breakthrough recurrences in each treatment group during a 6 month treatment period; time to first recurrence during treatment and follow-up after treatment cessation. RESULTS During treatment, acyclovir recipients showed significant differences (p < 0.05) when compared with isoprinosine recipients in terms of a lower proportion reporting recurrences (31% vs 96%), a reduced mean number of reported recurrences per patient (0.6 vs 3.6), a shorter mean duration of breakthrough lesions (6.4 days vs 8.2 days), and a longer mean time (standard error) to first recurrence (143.7 (9.1) days vs 40.5 (5.4) days. The mean time to first recurrence after treatment cessation did not differ between the two groups. As compared with placebo recipients, isoprinosine treated patients had an increased recurrence frequency (3.6 vs 2.5) during treatment, and a shorter time to first recurrence after treatment cessation. All treatments were well tolerated without serious adverse events or toxicity. CONCLUSIONS Acyclovir is very effective in suppressing recurrent genital herpes and is clearly superior to isoprinosine which is not clinically useful in the dosage studied.