April 9, 2013
U.S. National Institutes of Health (NIH) researchers report that a reduced-glycerin formulation of tenofovir gel was safe and acceptable to HIV-negative women and men who used the anti-HIV gel rectally in a phase I clinical trial (MTN-007).
NIH is studying rectal microbicides inserted rectally via an applicator as a means of preventing sexual transmission of HIV. In addition to developing rectal-specific products, researchers reformulated a vaginal product, tenofovir gel, for rectal use. The original vaginal formulation caused gastrointestinal side effects when it was used rectally.
The 2010 MTN-007 study divided 65 men and women into four groups for the one-week trial. One group used a reduced glycerin formulation of tenofovir gel daily; one used a placebo gel daily; one used the spermicide nonoxynol-9 daily; and one group used no gel. All study participants underwent the same "study-related procedures and tests." The three groups using gels reported no significant differences in side effects. Eighty percent had minor side effects, and only 18 percent reported moderate side effects. Compliance with daily use was high (94 percent), and 87 percent stated they would use the product again.
NIH plans a phase II multi-site trial (MTN-017) of the reformulated tenofovir gel in the United States, Thailand, South Africa, and Peru. The study will include 186 men who have sex with men and transgender women, all of whom will cycle through three regimens: daily use of tenofovir, use of tenofovir used before and after sex, and use of a daily antiretroviral pill (Truvada). The study will compare the reformulated tenofovir to Truvada and provide additional information about tenofovir gel safety.
The full report, "A Phase 1 Randomized, Double Blind, Placebo Controlled Rectal Safety and Acceptability Study of Tenofovir 1% Gel (MTN-007)," was published online in the journal PLoS ONE (2013; doi:10.1371/journal.pone.0060147).