Tenofovir gel is safe and well tolerated when used vaginally to prevent HIV transmission, according to a report in the medical journal AIDS.

Tenofovir administered as an intravaginal gel has been proven effective in blocking the transmission of simian immunodeficiency virus (SIV) in animal models, the authors explain. Dr. Kenneth H. Mayer from Brown University, Providence, Rhode Island and colleagues evaluated the safety and tolerability of tenofovir gel in HIV-negative and HIV-positive women and their male sexual partners.

Most participants of the 84 women reported at least one mild adverse event, the authors report, but specific adverse event patterns were not associated with gel concentration, sexual activity, or HIV status.

Just over half the women tested had low, but detectable blood levels of tenofovir at one or more points following dosing, the results indicate. Oral administration of tenofovir results in systemic exposure that is 10-times greater than the levels seen in this study, the investigators explain.

Among 12 women who had detectable blood levels of HIV, there were no new resistance mutations detected after gel exposure.

The vast majority of the women (94 percent) said they would definitely or probably use the gel if it were available and they wanted protection from HIV transmission, the report indicates. Similarly, 81 percent of their male partners agreed that they would use the gel under similar circumstances.

The higher dose used twice daily was just as well tolerated as the lower dose used only once a day, the investigators note.

Because tenofovir gel was well tolerated and acceptable in this study, a new trial of tenofovir gel in at-risk women “is now underway in New York and Pune, India, which may further support the rationale for efficacy trials of this promising new topical microbicide.”

SOURCE: AIDS February 28, 2006.