Background and objectives: Valaciclovir, the L-valine ester prodrug of acyclovir, is much better absorbed than acyclovir and produces acyclovir exposures three to five times those attainable with the parent drug.
Goals: To determine whether the improved bioavailability of valaciclovir and a more convenient, less frequent dose regimen can maintain the clinical efficacy previously demonstrated for acyclovir.
Study design: This was an international, multicenter, randomized, double-blind clinical trial comparing 10-day regimens of valaciclovir (1000 mg, twice daily) and acyclovir (200 mg, 5 times daily) in the treatment of 643 otherwise healthy adults (> or = 18 years of age) with first-episode genital herpes. Patients were evaluated clinically and lesions were staged and cultured on days 1, 2, 3, 5, 7, 10, 14, and then twice weekly until healed. Blood for herpes serology tests was obtained on days 1 and 14; hematology and chemistry toxicity screening was done on days 1 and 7.
Results: Valaciclovir and acyclovir did not differ significantly in efficacy with respect to duration of viral shedding (hazard ratio, 1.00; 95% confidence interval [CI], 0.84-1.18), time to healing (hazard ratio, 1.08; 95% CI, 0.92-1.27), duration of pain (hazard ratio, 1.0; 95% CI, 0.85-1.18), and time to loss of all symptoms (hazard ratio, 1.02; 95% CI, 0.85-1.22). Patients with primary genital herpes (no preexisting antibody to either herpes simplex virus type at enrollment with seroconversion at day 14) had longer times to healing and longer duration of viral shedding and pain than patients with nonprimary first genital episodes. Adverse experiences were generally infrequent and mild and were comparable in the two treatment groups.
Conclusions: Twice-daily valaciclovir proved as effective and well tolerated in the treatment of first-episode genital herpes as five-times-daily acyclovir. Valaciclovir provides a useful alternative to acyclovir with the advantage of a more convenient dosing regimen and the potential for improved compliance.