Research Examines Use Of Antiretroviral Pills, Gels For Possible 'Pre-Exposure Prophylaxis' For HIV

Several studies are examining whether periodic use of antiretroviral drugs in various forms -- including pills and vaginal or rectal gels -- can prevent HIV transmission during high-risk sexual encounters, according to researchers at the annual Conference on Retroviruses and Opportunistic Infections, the Washington Post reports. Some ongoing studies are assessing "pre-exposure prophylaxis" with antiretrovirals in sex workers and other groups at high risk for contracting HIV. Results from some of the studies could be available later this year.

Since antiretrovirals first became available in 1996, experts have debated how early, how long and how often the drugs should be used. For people who already have HIV, "[i]t's now clear that interrupting treatment is not a good idea and that starting it early in the course of infection may have real benefits, even though it means a lifetime of daily pill taking," according to the Post. If the new research is successful, it could mean that the drugs "are on the threshold of a new life as tools to prevent infection in individuals and brake the epidemic in populations as a whole," the Post reports. It is already known that administering antiretrovirals to newborns immediately after birth and during breastfeeding greatly reduces the chance of mother-to-child transmission. "We know that prevention works in babies. It shouldn't be any different in adults," John Mellors, a researcher at the University of Pittsburgh and chair of the conference, said (Brown, Washington Post, 2/21).

Gels Hold Promise for Women

The development of an antiretroviral gel that could prevent HIV transmission would be particularly beneficial to women. Women in Africa account for most new HIV cases and are often infected by their husbands, Reuters reports.

In a study presented at the conference, the drug maraviroc, sold by Pfizer under the brand name Selzentry, protected female monkeys from sexual transmission for about four hours after application. Weill Cornell Medical College's John Moore, who participated in the study, said that a vaginal ring with a time-release formula might work better for long-term protection. Selzentry is part of a new class of drugs called CCR5 entry inhibitors, which are designed to stop HIV from entering human cells. CCR5 inhibitors are not yet widely used for treatment in Africa, which means there is a lower risk that patients will develop resistance, Moore said.

Laura Guay of the Elizabeth Glaser Pediatric AIDS Foundation said her group supports the development of microbicides to protect women and, in turn, their children. "The hope is by putting antiretrovirals into the microbicide you can prevent the virus from either entering or replicating," she said (Fox, Reuters, 2/20).


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View drug information on Selzentry.