AIDS drugs promise prevention in a bottle

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"This is an approach we've considered for a long, long time," but didn't try sooner because AIDS drugs had side effects and risks unacceptable for uninfected people, said Dr. Mary Fanning, director of prevention research at the National Institute of Allergy and Infectious Diseases.

Tenofovir changed that when it came on the market in 2001. It is potent, safe, stays in the bloodstream long enough that it can be taken just once a day, doesn't interact with other medicines or birth control pills, and spurs less drug resistance than other AIDS medications.

The CDC last year launched $19 million worth of studies of it in drug users in Thailand, heterosexual men and women in Botswana, and gay men in Atlanta and San Francisco. A third U.S. city, not yet identified, will be added, CDC announced last week.

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Because of the exciting new monkey results, the Botswana study now will be switched to the drug combination; the others are well under way with tenofovir alone.

Farthest along is a study of 400 heterosexual women in Ghana by Family Health Initiative. The Bill & Melinda Gates Foundation funded it and others in Cambodia, Nigeria, Cameroon and Malawi, but the rest were doomed by rumors, including fears that scientists wanted to deliberately expose people to HIV or that study participants who got infected might not have access to treatment. In other cases, activists demanded better health care or clean needles for drug users as a condition for allowing the studies to proceed.

Such problems are "part of the HIV prevention landscape" in many foreign countries, said Dr. Helene Gayle, who formerly oversaw AIDS research for the Gates Foundation.

Drug combo costs $650 a month
Expense also could limit use of the drugs. Gilead donated them for the studies and sells them in poor countries at cost — 57 cents a pill for tenofovir and 87 cents for Truvada, the combination drug. That's more than the cost of condoms, available for pennies and donated by the truckload in Africa, but often unused.

In the United States, wholesale costs are $417 for a month of tenofovir and $650 for Truvada.

Still, health officials are hopeful the drugs could fill an important gap.

The National Institutes of Health is starting a tenofovir study in 1,400 gay men in Peru. Private and government funders are considering others. Tenofovir also is being tested in microbicide gels that women could use vaginally to try to prevent catching HIV.

"If you're in an area where there's a really high HIV incidence, something that's even 40 percent effective could have a huge impact," Paxton said.

And in the Atlanta labs where Heneine, Folks and others are still minding the monkeys, "the level of enthusiasm is pretty high," Heneine said. "This is very promising. For us to be involved in a potential solution to the big HIV crisis and pandemic is very exciting."

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