"The gel -- tenofovir -- is safe to use, and well tolerated by HIV-negative women. That's a key message in our findings," study author Dr. Craig Hoesley, of the University of Alabama at Birmingham said in a statement.

"This sets the stage for larger studies to see if tenofovir can prevent HIV infection."

Hoesley and colleagues at the University of Pittsburgh School of Medicine study included 200 sexually active HIV-negative women -- ages 19 to 50 -- 64 percent of whom were married.

The active ingredient in tenofovir gel is a class of anti-retroviral drugs called nucleotide reverse transcriptase inhibitors, which act against HIV by blocking the virus' ability to replicate and grow inside the body, Hoesley said.

The study findings were presented at an international microbicides meeting this week in New Delhi.