The study was marred by low use of the gel, which could have undermined results, they said. Women used it less than half the number of times they had sex, and only 10 per cent said they used it every time as directed.

Scientists are still analyzing the results to see if this made a difference. They also plan more tests on a revamped gel containing an AIDS drug that they hope will work better.

The gel used in the current study did prove safe, however, and researchers called that a watershed event.

But for now, the effort is the latest disappointment in two decades of trying to develop a microbicide ~ a cream or gel women could use to lower their risk of getting HIV through sex. A female-controlled method is especially needed in poor countries where women often can't persuade men to use condoms.

A year ago, scientists stopped two late-stage tests of a different gel after early results suggested it might raise the risk of HIV infection instead of lowering it.

The new study tested Carraguard, a microbicide developed by the nonprofit, New York-based Population Council. It contains carrageenan, which comes from seaweed and is widely used in the food and cosmetics industries as a gel, stabilizer and thickening agent. Lab, animal and early human tests suggested it might prevent HIV and other sexually spread infections.

From AIDSmap http://www.aidsmap.org/en/news/83D932E5-6D7B-4E45-AE95-17465D5FAAB8.asp 19 Feb 08