Effect of undecylenic acid as a topical microbicide against genital herpesinfection in mice and guinea pigs

There is increasing interest in the use of topical microbicides to help pre vent the spread of sexually transmitted diseases (STD). Undecylenic acid (U A), a monosaturated fatty acid, is the active ingredient in a number of ove r-the-counter (OTC) antifungal spray powders, that also exhibits in vitro a ntibacterial and antiviral activity, including herpes simplex virus (HSV) a ctivity. We, therefore, evaluated UA as a topical microbicide against genit al HSV infection using the murine and guinea pig models of genital herpes. Mice were administered a 20% solution of UA in polyethylene glycol (PEG) ve hicle, vehicle alone or phosphate buffered saline (PBS) intravaginally imme diately prior to vaginal challenge with HSV-2. Pre-treatment with UA decrea sed the number of mice that became infected (P<0.001 vs. PBS or vehicle con trol), developed symptoms (P<0.001) or died (P<0.001). However, when treatm ent was extended to either 5 min prior to or after viral inoculation, prote ction was lost. Similar findings were found using the guinea pig model, whe re UA treatment completely prevented HSV-2 vaginal infection when given imm ediately prior to HSV-2 inoculation (P<0.001 vs. PBS or vehicle control). T hus, UA, an approved OTC medication, provided significant protection agains t HSV disease and infection only when applied immediately before viral inoc ulation, indicating that better formulations were needed to extend the dura tion of protection. (C) 1999 Elsevier Science B.V. All rights reserved.