Future of AIDS gels may lie in drugs, experts say

AIDS experts have long been searching for a microbicide -- a cream, gel or vaginal ring that women or men could use as a chemical shield to protect themselves from sexual transmission of the deadly and incurable virus.

Several substances have been tried unsuccessfully but experiments presented this week at the Conference on Retroviruses and Opportunistic Infections, a scientific meeting of AIDS experts, suggested HIV drugs might hold the key to making such gels work.

"The next wave of compounds is all going to be based on antiretroviral drugs," Dr. John Moore of Weill Cornell Medical College in New York told reporters.

Moore's team tested Pfizer's new drug maraviroc, sold under the brand name Selzentry. It is in a new class of drugs called CCR5 entry inhibitors, designed to stop the human immunodeficiency virus from getting into human cells using a type of cellular doorway or receptor named CCR5.

"The CCR5 inhibitors are compelling candidates as an alternative because these drugs are not being used for treatment in, for example, Africa," Moore said.

That means there is less risk of resistance developing -- when viruses evolve to get around the effects of drugs.

Moore's team took a unique approach to formulating their experimental microbicide using Selzentry.

"We found a friendly physician, scrounged a tablet, ground it up," Moore said. "I assure you it actually works very well," he told the San Francisco meeting.

Tests in monkeys showed it would protect a female from sexual transmission for about four hours. "You couldn't apply these gels in the morning and have protection in the evening," Moore said.

A vaginal ring with a time-release formula may work better for longer-term protection, Moore said.

The approach is affordable, he said. "A single maraviroc tablet, about 300 mg, retailing for about $15 on the Internet, contains enough drug to fully protect around 15 macaques. That is broadly going to be applicable to women."

Laura Guay of the Elizabeth Glaser Pediatric AIDS Foundation said the approach sounds reasonable. Her group supports the development of microbicides to protect women and by extension their children.