Dr. Samuel Baron and colleagues conducted the study to examine over-the-counter vaginal preparations for their ability to inhibit HIV production.

While the spermicide nonoxynol-9 has been found in lab tests to fight HIV, it doesn't prevent the virus from spreading, probably because it causes genital irritation, the authors note in the July 20th issue of AIDS Research and Human Retroviruses. For this reason, the researchers only looked at non-irritating lubricants.

Astroglide lubes inhibited HIV production by more than 1,000-fold when mixed in test tubes with cells contained in semen. When the preparation was mixed with cell-free semen containing the virus, it cut HIV replication eightfold.

Inactivation of the virus began within 5 minutes after the preparation was added, and the lubricant remained active for more than 8 hours at human body temperature. When layered over cells, the lubricant was still able to kill, indicating that their protective activity can diffuse into seminal fluid. The lubricant was still active when diluted in a one-to-four ratio.

Since submission of their report, the investigators have identified two components that are responsible for the inhibitory effects, Baron told Reuters Health. These components appear to interact with the lipid or fatty membrane that surrounds both the virus and the infected cells, he said.

"These materials we have identified are by the most stringent standards safe, falling in the Food and Drug Administration's No. 1 safety category,'' Baron noted. ``This separates them out completely from nonoxynol-9.''

He cautions that condoms remain the recommended method for preventing HIV transmission during sexual activity. However, Baron and his colleagues highly recommend that field trials of these agents be conducted among people at risk.