Microbicides: Her Own STD Barrier

"Women deserve more options than begging their husbands to use a condom," says Sharon Hillier, a scientist at Magee-Women's Research Institute in Pittsburgh. But begging is too frequently a woman's only defense against STDs, and these pleas are often ignored -- one reason more than 19 million women in the world have AIDS. But women soon may have the power to prevent HIV and other STDs on their own.

Microbicides -- gels and ointments applied directly to the vagina -- aim to provide this protection. Carraguard, a microbicide expected to enter clinical trials later this year, is just one of nearly 60 products in development. The Bill and Melinda Gates Foundation just granted $60 million to microbicide research, and if all goes well, a product could be on the shelf by 2007.

Carraguard is a gel made from seaweed. Applied no more than an hour before sex, the gel is chemically attracted to proteins on pathogens like HIV and herpes. Other compounds take different approaches. Some can boost the vagina's natural pathogen-killing acidity, while others strip viruses of their protective shield or prevent a virus from replicating inside a cell. Human studies have shown that Carraguard is safe, and animal research and other compounds shows that it works. Effectiveness in humans is harder to prove. It is unethical to intentionally expose people to HIV, so trials must track thousands of women who are already at risk of contracting the virus to learn if those who use gels escape infection. A product does not have to be foolproof: Investigators would be thrilled with a 30 percent to 50 percent reduction in infections.

The biggest obstacle to microbicide research is the cost of the trials. The largest demand for the products is from poor women in AIDS-besieged areas of Africa and Asia. With a few exceptions, nonprofit and government spending has financed research and early testing. For long-term development, however, "the western world is important because that's where the money is," said David Phillips, senior scientist at the Population Council, which is developing Carraguard. To win over western customers interested in birth control, a microbicide might include a spermicide -- an approach that would not work in developing nations, where fertility is highly valued.

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