The risk of becoming infected with HIV from unprotected anal sex may be at least 20 times greater than unprotected vaginal sex, but early results have shown that a gel proven to guard against HIV infection during vaginal intercourse has also shown promise of defending against the viral spreading of HIV during anal sex too. The 18th Conference on Retroviruses and Opportunistic Infections (CROI) is taking place this week in Boston and this new promising information was discussed there.
Ian McGowan, M.D., Ph.D., co-principal investigator of the Microbicide Trials Network (MTN) and professor of medicine at the University of Pittsburgh comments:
"We are very encouraged about these findings that indicate applying tenofovir gel topically to the rectum could be a promising approach to HIV prevention. These are early results, but help set the stage for current and future trials of rectal microbicides and the development of a rectal-specific formulation of tenofovir gel."
The results, based on rectal tissue biopsies sampled from HIV-negative men and women who used the product daily for one week, provide the first-ever evidence that tenofovir gel could help reduce the risk of HIV from anal sex, even though the vaginal gel formulation may not be optimal for rectal use.
At the XVII International AIDS Conference in Vienna in July 2010, it was shown that use of a vaginal gel containing the antiretroviral drug tenofovir reduced the risk of HIV infection by 39% for women who received the product in a placebo-controlled study conducted in South Africa.
Microbicides, products applied on the inside of the rectum or vagina, are being designed and tested to help prevent or reduce the sexual transmission of HIV or other sexually transmitted infections. The majority of microbicide research thus far has focused on products to prevent HIV during vaginal sex.
The researchers found that HIV was significantly inhibited in tissue samples from participants who used tenofovir gel daily for one week compared to tissue from participants who used the placebo gel. While a slight anti-viral effect was noted in tissue from participants who received a single dose of tenofovir gel, the finding was not statistically significant. The single dose of oral tenofovir did not provide any protection against HIV in rectal tissue samples.
Peter Anton, M.D., professor of medicine and director of the Center for Prevention Research at the University of California, Los Angeles (UCLA) adds:
"These kinds of efforts early in the development phase of rectal microbicides can give us insight into a particular product's potential efficacy, which enables us to better design and hasten the pace of future clinical trials. These results tell us that tenofovir gel was relatively safe to use in the rectum for most participants, but we need to address side effects to make it more acceptable to use. Even though three-quarters of the participants reported they didn't like the gel, we are very encouraged that the majority would consider using such a product in the future."
Only 25% of men and women who had used the tenofovir gel said they liked it. However, when asked whether they would consider using the product in the future, 75% of these participants reported a high likelihood of future use.
Source: News Release
Written by Sy Kraft, B.A.