Background: Famciclovir, the well absorbed oral pro-drug of penciclovir, is effective in the treatment of herpes zoster when given three times daily. Because the intracellular half-life of penciclovir triphosphate in varicella-zoster virus (VZV)-infected cells (7h) is considerably longer than that of aciclovir triphosphate (1h), it may be possible to administer famciclovir less frequently than three times daily for herpes zoster: aciclovir is administered five times daily.
Methods: 559 immunocompetent adults presenting with herpes zoster whose skin lesions were present for less than 72 h were randomized to receive famciclovir 750 mg once daily (od), 500 mg twice daily (bid), or 250 mg three times daily (tid), or aciclovir 800 mg five times daily. All treatments were given for 7 days. Participants were evaluated until complete healing or for 4 weeks, whichever occurred first.
Results: There were no significant differences between the four treatment groups with respect to times to full crusting; loss of vesicles, ulcers and crusts; cessation of new lesion formation; a 50% reduction in the area of affected skin; and the loss of acute pain.
Conclusions: Famciclovir 750 mg once daily, 500 mg twice daily and 250 mg daily, and aciclovir 800 mg five times daily are three times comparable in efficacy with respect to the cutaneous healing of herpes zoster. The current study was not designed to assess the effects of the treatments on postherpetic neuralgia (PHN).