NEW ORLEANS — Treatment with once-daily, high-dose valacyclovir significantly decreases the duration and quantity of oral herpes simplex virus-1 shedding associated with recurrent herpes labialis, according to data from a randomized study.
Oral shedding, either associated with known outbreaks of herpes labialis or, perhaps more importantly, during asymptomatic periods, is the presumed mode of transmission of herpes simplex virus-1 (HSV-1), Stan C. Gilbert, M.D., said in a poster presentation at the annual meeting of the American Academy of Dermatology.
HSV-1 causes gingivostomatitis in infants and children and recurrent cold sores in most people. It also has become the primary cause of genital herpes in the majority of cases among young adults. Recurrent herpes labialis (RHL) affects up to 40% of HSV-1-seropositive adults.
Research has shown oral shedding associated with episodes of RHL lasting from 1 to 8 days. But the studies are rare and have relied mostly on viral cultures, according to Dr. Gilbert, of the University of Washington, Seattle.
His study randomized 64 adults with a history of three or more RHL episodes a year to four 500-mg valacyclovir (Valtrex) caplets taken at the first sign of an outbreak or placebo. The dosing was repeated 12 hours later. Polymerase chain reaction (PCR) swabs were collected every 12 hours starting at the first sign of outbreak and continuing for 10 days. Both groups had a history of cold sores for an average of 28 years and an average of four cold sores in the previous 12 months.
Patients receiving valacyclovir experienced fewer days of shedding than did the placebo group (1.8 vs. 4 days). A comparison of the log HSV-1 DNA copies detected by PCR over time, using the average area under the curve (AUC), showed significantly less shedding from the valacyclovir-treated patients than from the placebo-treated patients (average AUC 1.1 vs. 2.2).
The study's findings are important because information about the natural history of oral HSV-1 shedding and the impact of antivirals may help to reduce transmission rates, Dr. Gilbert said. Dr. Gilbert is a member of the speakers' bureau for GlaxoSmithKline Inc., which manufactures Valtrex and provided 50% of the funding for the study.