May 29, 2002
To date most of the reported new treatments for type 2 herpes virus-induced labialis have been with topical formulations of antiviral drugs. Oral valaciclovir is a modified form of acyclovir that is better absorbed from the gastrointestinal tract compared with acyclovir, and which is converted 100 percent to acyclovir after absorption, increasing acyclovir blood levels several fold compared with administration of the parent compound. Dr. Spotswood Spruance and his coworkers at the University of Utah studied valaciclovir to see if higher drug concentrations would increase drug efficacy in herpes labialis. They also examined the feasibility of very abbreviated treatments -- only one or two days of therapy -- to see if this patient-friendly dosing plan would be effective. Evidence has long existed that most of the damage from the herpes simplex virus occurs very early in the course of the infection.
At the International Conference on Antiviral Research in Prague, the authors reported the results of two randomized, double-blind, placebo-controlled trials of high-dose valaciclovir for 1 or 2 days on the duration of herpes labialis lesions. Subjects received valaciclovir 2 g bid x 1 day, valaciclovir 2 g bid x 1 day -- then 1 g bid x 1 day, or placebo and began treatment at the first prodromal symptom of a new episode. A total of 3,151 subjects were enrolled, of whom 1,856 treated a cold sore episode.
Valaciclovir shortened the duration of the cold sore episode in the total study population by 0.7-1.1 days (13-16%). The effect of valaciclovir on the healing time of classical lesions (episodes that evolved to blisters or ulcers) was substantially greater (1.1-1.5 days, 18-24 percent). Further, increases of 20 percent in the proportion of valaciclovir subjects with aborted lesions (lesions not progressing beyond redness and swelling) were observed which were statistically significant when the studies were combined. Treatment for one day was just as good as treating for two days. These studies provide evidence supporting a simple, unique one-day valaciclovir regimen that has clear dosing advantages over available topical and oral therapies.