20100720
allafrica

Johannesburg — A vaginal gel containing Gilead Science's AIDS drug tenofovir almost halves the risk of women getting HIV from their male partners, according to a South African study presented today at the 18th International AIDS Conference in Vienna.

It is an important step towards developing a product over which women will have control, of which there are none at present. It is also set to give fresh impetus to a field littered with disappointment, as 11 trials of six microbicide products over the past 15 years all failed.

"It's been a long road getting here," said the study's co-principal investigator Professor Salim Abdool Karim, director of the University of KwaZulu Natal's Centre for the AIDS Programme of Research in SA (Caprisa). He was involved in testing several of the failed microbicides, including a seaweed based product called Carraguard.

"It is only the first step. It needs confirmation," he said in an interview with Business Day.

Women are disproportionately affected by HIV, particularly in sub-Saharan Africa where they constitute 60 percent of all infections. Yet the only HIV prevention technology currently available to them is the condom, which not all men will use. Male circumcision gives men partial protection from HIV transmitted by women, and there is still no vaccine.

"Picture a young woman in a rural community in South Africa who walks through my clinic doors asking me what I have to protect her from getting infected," said co-investigator Dr Quarraisha Abdool Karim.

"From being able to tell her for years that I have nothing, I can now offer her tenofovir gel," she said in a teleconference.

The phase 2 study included 889 women who used the gel before and after sex with their male partners. Half the volunteers used the tenofovir gel, and half used a dummy version that appeared identical. Neither the volunteers nor the researchers knew which version the women had received until after the study was completed.

The gel reduced HIV acquisition by 39% overall, and by 54% in women who used it consistently. No dangerous side-effects were reported. It also halved the risk of contracting genital herpes, which is widespread in SA and increases vulnerability to HIV infection.

The gel, which contains 1% tenofovir, works by preventing HIV from reproducing inside the body. Previous candidate microbicides have been surfactants, which tried to stop HIV entering the body.

If further trials of the tenofovir gel prove successful, the product will need to be approved by regulators such as the Medicines Control Council before it can be marketed.

Professor Karim said he was optimistic that a microbicide containing tenofovir would be affordable for Africa, as Gilead had an agreement with the government's Technology Innovation Agency enabling SA to manufacture the gel without paying royalties.

Further research should also be pursued to see if combining two or more AIDS drugs in a microbicide would give women greater protection than the tenofovir gel, he said.

Prof Karim said experts needed to start thinking about creative ways to market microbicides:

"I think the future will involve making this gel sexy, something that is part and parcel of sex, that enhances it. Durex finds such amazing ways to package their condoms. We need to find ways to package it (the gel) so women want to use it," he said.