http://allafrica.com/stories/200802150835.html

TESTS on a gel meant to protect women against HIV infection have been scaled down after one of the formulations was found to be ineffective. The gel, scientifically described as a vaginal microbicide and code-named PRO2000/5, has been on trial in Uganda, Tanzania, Zambia and South Africa.

The principal investigator of the study in Uganda, Dr. Anatoli Kamali, on Thursday said the microbicide was being tested in two different concentrations: 2% and 0.5%. For comparison, a third group of women were using a similar but inactive substance known as placebo.

However, early results showed that the 2% PRO2000/5 was unlikely protect women from HIV infection. "We had hoped that either of the two would work. But after examining the data on the safety and efficacy collected to date, the monitoring committee recommended that the 2% arm be halted and only the 0.5% and the placebo gel arms of the trial should continue," Kamali said.

It was not clear why the 2% microbicide, which is more concentrated, was not effective. At least 7,735 women have already been enrolled for the trials in the four countries, out of a targeted 9590.

Kamali said those taking the 0.5% concentration or placebo would continue until June 2008. The gel is inserted into the vagina an hour before sexual intercourse, and left in for at least an hour after.

Several microbicides have been tested since the late 1990s but so far none has proved effective in preventing HIV infection.

Microcide research is part of global efforts to find a protective substance that can be controlled by women. Whereas women become infected with HIV more easily, the most available protective tool – the condom – remains a male-controlled device.

Prof Heiner Grosskurth, the Director of HIV research at the Uganda Medical Research Council said the concept of microbicides began 10 – 15 years ago but researchers have not yet found one to be working. Last year, another trial was discontinued after it was found ineffective.