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Could contribute an almost 30-year campaign against AIDS

Researchers may have found a HIV preventative gel, which contains an AIDS drug already on the market, that could decrease a woman's chances of getting HIV in half. It was announced at the International AIDS Conference in Vienna, but further testing is required to make sure the product is safe and effective. 

AIDS has claimed 25 million lives total, and 33 million more are infected by HIV. Of this total, two-thirds are from sub-Saharan Africa. In this area, 60 percent of new infections develop among women and young females. 

For years, the only way to prevent HIV infection was by the use of condoms and male circumcision, since the foreskin contains cells that are "vulnerable to penetration by HIV." But the latter only prevents HIV infection in males. 

The study was led by Quarraisha Abdool Karim and Salim Abdool Karim from the Centre for the AIDS Programme of Research in South Africa (CAPRISA) in Durban. It consisted of almost 900 South African women who were sexually active and between the ages of 18 and 40, where 444 received a placebo and 445 received the microbicide gel. It was conducted in both the urban setting of Durban and the rural setting of Pietermaritzburg in the KwaZulu-Natal province.

Over a three year period, these women were asked to apply the gel, which contains a mixture of antiretroviral drugs and a one percent formulation of tenofovir that interrupts the reproduction of HIV in immune cells, with a vaginal applicator within a 12 hour window before intercourse and within a 12 hour window after intercourse. They were then tested for HIV on a monthly basis. In comparison to the placebo group, those who used the microbicide reduced the risk of HIV by 39 percent overall. For those who used the microbicide more often, as directed, 54 percent of the risk of HIV was reduced. 

"Without this gel, we may see 10 women becoming infected in a year," said Salim Abdool Karim. "With this gel, we would see only six women becoming infected."

While no major side effects were observed over the course of the study, the gel did become less effective after 18 months of use, and researchers are looking into finding out why. Right now, they believe it may be due to the fact that 40 percent of the women "used the microbicide less than one time out of two." Also, they will continue testing the gel to make sure there are no long term side effects that will exist beyond a three year period. 

The study has been published in the journal Science and could prove to be a vital part of finding efficient, preventative ways to avoid HIV infection everywhere.

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Glad to See this Made it to DT
By clovell on 7/21/2010 11:40:20 AM , Rating: 3
First of all, thanks for taking the time to write this up, Tiffany. The study was definitely a proof of concept, but it's particularly cool to see that Gilead was able to make tenofovir bioavailable in a gel form.

Anti-retrovirals (ARVs) used to fight HIV have a long history of being finicky when it comes to stability. Especially in terms of formulation or heat resistance.

I do take particular issue with the study when it claims that the gel does not confer viral resistance. Viral resistance for this class of drugs (Protease Inhibitors) is generally determined by genotyping the virus and seeing if mutations occur during the course of treatment, which are known to confer resistance.

Now, this is usually tested on at least a thousand infected subjects. Since this was an anti-infective trial, with <900 patients, and <10% infection rate, we really only have 100 patients to check for resistance on. However, it's good to see that they found no evidence of the gel conferring resistance.

In any event, it will be interesting to see where this goes. Tenofovir's mechanism of action is to prevent the virus from replicating. It doesn't kill HIV. It stops the virus protease from cleaving the virus (mitosis), and eventually the virus recedes. I'm interested to understand how it works here.

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