Randomized clinical trial of famciclovir or acyclovir for the treatment of herpes zoster in adults.

Background: This study investigated the safety and efficacy of famciclovir compared to acyclovir in patients with herpes zoster, to determine whether the two regimens are equally effective for the treatment of patients with uncomplicated herpes zoster over a period of 7days.

Methods: Patients were randomly assigned to receive either famciclovir 500mg (one tablet) three times daily or acyclovir 800mg (two capsules) five times daily for 7 days. The primary endpoint was defined as the time to full crusting of herpes zoster lesions. Secondary endpoints were the proportion of patients who achieved complete cure and the change in score of signs/symptoms (pain, vesicular lesions, loss of sensitivity, burning pain, and pruritus) according to the patient diary. This study has been registered at ClinicalTrials.gov (NCT01327144).

Results: One hundred and seventy-four patients were enrolled and randomized; 151 of these patients completed treatment (n=75 famciclovir, n=76 acyclovir). A similar proportion of patients who received acyclovir (94.74%) and famciclovir (94.67%) achieved complete cure. The mean time to full crusting of herpes zoster lesions was 15.033days in the acyclovir group and 14.840days in the famciclovir group (log-rank p-value=0.820). The most common adverse events in the pooled groups were headache, diarrhea, nausea, back pain, cold, and drowsiness, but none of these was deemed to be clinically important.

Conclusions: Both interventions obtained high rates of cure and had a similar time to full crusting of lesions. Analysis of the primary efficacy endpoint proved that famciclovir is non-inferior to acyclovir, as the confidence interval for the difference in efficacy did not violate the non-inferior margin. Therefore, the results are not different enough to be clinically relevant.