Use of lubricants with anal sex could increase risk of HIV

The risk of acquiring HIV through unprotected anal sex is at least 20 times greater than with unprotected vaginal sex and increases if other infections are already present in the rectal lining. Could the use of lubricants – at least certain kinds – be another risk factor among men and women who engage in receptive anal intercourse? Two studies presented today at the International Microbicides Conference in Pittsburgh, suggest the answer is yes.

In one study involving nearly 900 men and women in Baltimore and Los Angeles, the researchers found that those who used lubricants were three times more likely to have rectal sexually transmitted infections (STIs). Another study that subjected popular over-the-counter and mail-order lubricants to rigorous laboratory tests discovered that many of the products were toxic to cells and rectal tissue. If in humans, these products have the same effect, the cells might be rendered more vulnerable targets for HIV infection than they already are.

In the United States alone, receptive anal intercourse is practiced in up to 90 percent of gay and other men who have sex with men, according to International Rectal Microbicides Advocates. Moreover, the practice is not limited to men. U.S. estimates and surveys in the United Kingdom indicate between 10 to 35 percent of heterosexual women have engaged in anal sex at least once. Globally, estimates suggest 5 to 10 percent of sexually active women are having anal sex. While condoms are generally effective for protecting against HIV and other STIs, most acts of anal sex go unprotected.

Microbicides – substances applied topically on the inside of the rectum or vagina – could potentially help prevent the rectal transmission of HIV, and some are being tested in early Phase I safety studies. Another approach called oral pre-exposure prophylaxis (PrEP) involves the use of antiretroviral drugs to reduce the risk of HIV in HIV-negative people. A large Phase III trial of PrEP involving men who have sex with men in South America, Africa and the United States is expected to report results by early next year. Yet, if either of these approaches is found effective in clinical trials, they will do no good if those most at risk don't use them. Other research presented today sheds light on this issue. Summaries of all three studies are provided below.

M2010 is taking place May 22-25 at Pittsburgh's David L. Lawrence Convention Center. Nearly 1,000 participants from 47 different countries are attending the meeting to hear about the latest developments in HIV prevention research.

Use of lubricants with anal sex associated with more rectal STIs

Lubricants are typically used before and during receptive anal intercourse, but their use could increase the risk of rectal sexually transmitted infections (STIs), a study involving nearly 900 men and women in Baltimore and Los Angeles has found. Even after controlling for gender, HIV status, city, condom use, and number of sex partners in the past month, the association between lubricant use before receptive rectal intercourse and rectal STIs remained strong, reported Pamina Gorbach, Dr.PH, from the School of Public Health and the David Geffen School of Medicine at the University of California, Los Angeles, who led the study. According to the study's statistical analysis that considered the HIV status, gender, condom use and study site, participants who used lubricants before receptive anal intercourse were three times more likely to have a rectal STI. Although the analysis didn't consider the specific lubricants being used, it may be that certain types of products are more irritating to the lining of the rectum than others, which could increase men and women's vulnerability to rectal STIs, the researchers suggest.