Microbicides - Women Wait
posted: 18/05/2010
Next week’s International Microbicides Conference in Pittsburgh, USA will hear about the progress made in producing microbicides, that will help protect women and gay men from HIV.
Numerous past attempts at microbicides have failed. Using an anti-HIV drug in a microbicide is one of the attempts now being made to find some method of HIV prevention that women can use themselves. Women face problems protecting themselves from HIV, especially when their partners refuse to use condoms, or when simply suggesting condoms may put the woman in danger.
Is tenofovir part of the answer?
Tests are underway to see if tenofovir, one of the commonly used anti-HIV drugs, would work in vaginal gels and contraceptive-style rings. Experiments are also underway with quick-dissolving anti-HIV films, like those used for breath-fresheners or allergy medicines, but these are made for vaginal use.
In July we should have the results from the first study to see if tenofovir works in a microbicide — South African women are testing a gel made with it.
Cautious Hope
"Frankly, blocking transmission of the virus appears to be a lot harder than anyone understood it would be at the beginning," says co-chair Dr. Sharon Hillier of the University of Pittsburgh and a principal investigator of the Microbicide Trials Network. "The reason we're not depressed in the microbicide world? We actually have learned a lot and moved on to think about potent drugs and really cool delivery methods."
Pills for Prevention?
More than half a dozen studies of ‘pre-exposure prophylaxis’ (taking pills as treatment to prevent HIV infection happening) are also under way, and these mainly use tenofovir, because the side effects are more limited than with some other anti-HIV drugs. But even if pills for prevention works, taking HIV pills daily has drawbacks. There are the side effects, the risk of drug resistance, and people may miss doses or share the tablets with others so they wouldn’t be effective. It’s more expensive protection than condoms and the risks make it controversial.
Microbicide action
Microbicides are needed too. Women already make up half of the more than 33 million people worldwide living with HIV, and most of the new infections in hardest-hit sub-Saharan Africa are among young women.
"I have in fact so little to offer women in terms of HIV prevention that I sort of tear my hair out," says Dr. Salim Abdool Karim of the Centre for the AIDS Program of Research in South Africa at the University of KwaZulu-Natal. He’s leading the tenofovir gel study, his ninth microbicide study since 1994. "It must take a certain level of perseverance to want to stay in this field." Much more of the tenofovir reaches the vaginal tissue from a gel than any pill, and it doesn’t seem to move elsewhere into the body, so side effects may be minimal. He’s studying 900 HIV-negative heterosexual women to test whether tenofovir gel, applied up to 12 hours before intercourse and again within 12 hours afterward, lowers the risk of infection.
Next step soon
While awaiting his results in July, the U.S. National Institutes of Health is funding the next step: Researchers are already looking for 5,000 healthy women in several African countries to try two other approaches - vaginal tenofovir gel used daily rather than before and after sex, or or daily tenofovir pills. Which way is best?
Contraception teaches us that offering more choice about method leads to more women using something. So researchers are looking at other methods, too: a quick-dissolving tenofovir vaginal film, which should be completely invisible to the partner. Vaginal rings might be used to trickle-dose the vagina over a month. And for gay men ways to protect the rectum with tenofovir are in prospect.
Health promotion workers should get themselves ready to deal with the challenges should any of these attempts work, Dr. Regina Osih of the University of Witwatersrand will advise next week's microbicide conference.
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