ALBUQUERQUE – A single buccal application of acyclovir delayed recurrence of herpes labialis by an average of 100 days, compared with placebo, according to the results of a randomized, double-blind, phase III study.
The 50-mg buccal mucoadhesive tablet also reduced recurrence of herpes labialis by 9.4% during the 9-month follow-up period, Dr. Christopher Downing said at the annual meeting of the Society for Investigative Dermatology.
The tablet is designed to be applied to the gum above the canine incisor at the time of prodromal symptoms, said Dr. Downing of the Center for Clinical Studies in Webster, Texas. Patients hold the tablet in place for 30 seconds, and acyclovir is then absorbed into the labial mucosa for the next 6-8 hours, Dr. Downing said, adding that salivary and mucosal concentrations remain at high levels for at least 24 hours.
"We know that the replication of HSV-1 is highest before and during the first hours of prodromal symptoms," Dr. Downing added. "Therefore, rapid and high concentrations of antiviral drug are needed."
The researchers enrolled 775 immunocompetent patients who had experienced at least four recurrent episodes of herpes labialis in the past 12 months. Patients had to be able to identify their prodromal symptoms to be enrolled in the study. A total of 378 patients were randomized to receive the acyclovir buccal tablet, while 397 were randomized to placebo. In all, 537 patients were evaluated during the entire 9-month follow-up period, and 59 patients had missing data.
A total of 330 patients had recurrence of a primary vesicular lesion, but a significantly fewer 149 (64.2%) in the treatment group vs. 181 (73.6%) in the control group (P = 0.027). In a subanalysis of 415 patients who applied the tablet within the first hour after noticing prodromal symptoms, lesions recurred in 63.2% of the treatment group and in 71.6% of the placebo group, said Dr. Downing.
The time to the next recurrence in the treatment group was 304 days (standard deviation, 19.4 days), compared with 199 days for the placebo group (SD, 9.3 days; P = 0.042).
The tablet "may modify the clinical course of labial herpes," the investigators noted. "By having a high salivary concentration and a high mucosal concentration of acyclovir during the time of highest replication, we’re seeing a difference in time to recurrence," said Dr. Downing. "We’re not sure exactly what the mechanism of action is."
Senior author Dr. Pierre Attali is with BioAlliance Pharma in Paris, which manufactures acyclovir Lauriad, a mucoadhesive buccal tablet.