University of Utah researchers have created a substance that can be applied as a liquid in the vagina, where it turns into a protective gel coating. When the gel is exposed to semen, antiviral drugs are released, said Patrick Kiser, a bioengineering researcher at the U.

This substance, referred to as a "smart molecular condom," is part of a family of drugs known as microbicides. Scientists are developing various gels, rings and creams in an effort to prevent transmission of the HIV virus, which can lead to AIDS.

Current microbicides now being tested in humans are designed to be used about an hour before intercourse. The U.'s proposed drug delivery system, reported this week in the Journal of Pharmaceutical Sciences, could be applied once a day at any time.

Researchers hope such a product could help empower women by allowing them to protect themselves against AIDS in developing nations where the disease is widespread.

"It would be nice to have something a woman can control," said Kavita Gupta, a U. graduate student who was a study author. "They don't have to negotiate the use (of a microbicide) with a man."

She said many women in developing nations do not have the bargaining power to force a man to wear a condom. In some cases, condoms are considered taboo or else they are not easily available.

The gel condom is the one of several ways to deliver drugs that Kiser's lab is studying.

"We are building a whole set of delivery technologies that are customized for women," he said.

It could be five years before such a delivery system is tested in humans, and widespread use could be at least a decade away, said Kiser, an author on the study.