London, February 20 : A seaweed-derived vaginal gel microbicide called Carraguard, which happens to be the first anti-HIV microbicide to make it to the end of phase III clinical trials, has failed to prevent transmission of the virus.
The trials involved 6,202 women in South Africa-half of whom were administered Carraguard gel, while the rest received a placebo gel. The subjects were also given condoms.
According to the researchers, 134 new infections were recorded in the Carraguard group during the study, as compared to 151 in the placebo group. The difference was not statistically significant, they said.
"The results are the results. The gel doesn't work," Nature magazine quoted Alana de Kock, principal investigator for the portion of the trial run from the University of Cape Town, as saying.
The results of the trial, organised by a New York-based non-profit research organization called Population Council, add to the round of bad news about microbicide gels, five of which were found to be ineffective in curbing HIV infections in the recently conducted trials.
Carraguard is based on the natural compound carrgeenan. It showed some promising results in early animal trials.
"Based on the basic science in the lab it was a very, very positive product. (But) those are very controlled environments," said de Kock, insisting that working with humans involved many more challenges.
"The bottom line is it hasn't worked in real women, in the real world," she said.
Although the human trial did not show any promising results, the South African health minister has commended the Population Council for the way women participants received care during the study.
Alana de Kock also insisted that it was important to note that the trial ran to completion, suggesting that Carraguard might be safe for long-term use.
"It's important to prove you can do a trial successfully in a community," she said.
Melissa May, a spokesperson for the Population Council, has revealed that the research team is now working on a combination of Carraguard and an antiretroviral drug, a product they call PC815. This product is now in early safety trials with people.