Acyclovir treatment of acute
herpes zoster speeds
rash healing and decreases
pain and ocular complications. The limited oral bioavailability of
acyclovir necessitates frequent dosing.
Valaciclovir, the l-valyl
ester of
acyclovir, is rapidly and almost completely converted to
acyclovir in vivo and gives three- to fivefold increases in
acyclovir bioavailability. In a randomized, double-blind, multicenter study, the safety and efficacy of oral
valaciclovir given at a dosage of 1,000 mg three times daily for 7 or 14 days and oral
acyclovir given at a dosage of 800 mg five times daily for 7 days were compared in immunocompetent adults aged > or = 50 years with
herpes zoster. Patients were evaluated for 6 months. The intent-to-treat analysis (1,141 patients) showed that
valaciclovir for 7 or 14 days significantly accelerated the resolution of
herpes zoster-associated
pain (P = 0.001 and P = 0.03, respectively) compared with
acyclovir; median
pain durations were 38 and 44 days, respectively, versus 51 days for
acyclovir. Treatment with
valaciclovir also significantly reduced the duration of
postherpetic neuralgia and decreased the proportion of patients with
pain persisting for 6 months (19.3 versus 25.7%). However, there were no differences between treatments in
pain intensity or quality-of-life measures. Cutaneous manifestations resolved at similar rates in all groups. Adverse events were similar in nature and prevalence among groups, and no clinically important changes occurred in hematology or clinical chemistry parameters. Thus, in the management of immunocompetent patients > or = 50 years of age with localized
herpes zoster,
valaciclovir given at 1,000 mg three times daily for 7 days accelerates the resolution of
pain and offers simpler dosing, while it maintains the favorable safety profile of
acyclovir.