GlaxoSmithKline (GSK) announced that a US Food and Drug Administration (FDA) Advisory Committee unanimously recommended the approval of once-daily suppressive therapy with Valtrex (valacyclovir HCl) for the reduction of transmission of genital herpes in otherwise healthy, heterosexual, monogamous couples.

The committee advised the FDA that suppressive therapy with Valtrex, in addition to safer sex counseling and use of condoms, was shown to be safe and effective in reducing transmission of genital herpes in heterosexual, otherwise healthy individuals. The committee's favorable recommendation will be considered by the FDA in its review of the supplemental new drug application (sNDA) GSK has submitted for Valtrex.

"We are extremely encouraged by this recommendation which recognizes the need for an important new therapeutic approach addressing a major concern of patients: transmission of genital herpes to their partners," said Clarence L. Young, M.D., vice president, Clinical Development and Medical Affairs, GlaxoSmithKline. "We look forward to working with the FDA to further progress this application."

The FDA is not bound by the committee's recommendation, but takes such advice into consideration when determining its decision on an application.

The study undertaken in support of the sNDA showed that once-daily suppressive therapy with Valtrex 500 mg caplets reduced transmission of symptomatic genital herpes (signs or symptoms of an outbreak confirmed with a lab test) by 75 per cent versus placebo (0.5 per cent vs 2.2 per cent) in 1484 healthy, heterosexual, monogamous couples. In addition, suppressive therapy with Valtrex reduced the overall acquisition of the virus (determined by a positive lab test) by 48 per cent versus placebo (1.9 per cent vs. 3.6 per cent).

Throughout the study, all couples were counseled on safer sex practices at all study visits and encouraged to use condoms; condoms were offered free of charge. The principles of safer sex practices were to avoid sexual contact when the source partner had any symptoms of genital herpes and consistent and correct use of condoms during all sexual contacts.

In this study, Valtrex was generally well-tolerated. The most commonly reported side effects in the study were headache (Valtrex 29 per cent, placebo 26 per cent), nasopharyngitis (Valtrex 16 per cent, placebo 15 per cent), upper respiratory infection (Valtrex 9 per cent, placebo 10 per cent), sore throat (Valtrex 8 per cent, placebo 7 per cent) and diarrhea (Valtrex 8 per cent, placebo 7 per cent). The effect of Valtrex on transmission of genital herpes has not been studied among individuals with multiple partners, non-heterosexual couples, couples not counseled on using safer sex practices, nor in people with HIV. The effect of Valtrex on transmission has not been studied beyond eight months.