Tenofovir Gel: A New Microbicide for Women?
Tenofovir disoproxil fumarate (Viread, Gilead), an oral medication that inhibits retroviral replication, could have a new life as a convenient vaginal gel, say researchers from Harlem Hospital Center, Bronx-Lebanon Hospital/Center, University of Pennsylvania, and Miriam Hospital in Providence, Rhode Island.
In the first phase 1 clinical trial to evaluate an antiretroviral agent as a vaginal microbicide, tenofovir vaginal gel was well tolerated. The study included 60 HIV-negative women and 24 HIV-positive women.
The women used either 0.1% or 0.3% tenofovir gel for 14 consecutive days between menstrual periods. Adverse events were generally mild; most of the women and their male partners said that they would probably use the gel if it were available. Pharmacokinetic testing demonstrated that 14 of 25 women had detectable plasma levels of tenofovir at least once.
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Longer-term studies are needed to determine whether the drug accumulates to toxic levels or whether tissue penetration enhances the gel’s protective effects. However, thousands of HIV-positive patients have tolerated daily tenofovir for up to five years.
None of the HIV-positive women with detectable plasma or cervicovaginal HIV RNA developed mutations associated with tenofovir resistance—a “reassuring” finding, the researchers note. Longer-term studies are recommended to evaluate chronic use.
