Another study -- the fourth in about a decade -- has found the substance does not protect women against two STDs, gonorrhea and chlamydia. Previous studies have shown nonoxynol-9 did not protect against HIV, and might even facilitate transmission of the deadly AIDS virus.
The new findings appear in tomorrow's issue of the Journal of the American Medical Association.
"We had high hopes for nonoxynol, based on some studies in the late 80s and early 90s, but the best evidence we have to date shows no impact at all," says lead author Dr. Ward Cates. "The evidence shows that nonoxynol does not protect against HIV or gonorrhea and chlamydia."
Ward is president of the Family Health Institute of Family Health International, the North Carolina-based organization that conducted the study.
"Women are desperately in need of a method that's within their control to prevent their getting HIV," says Dr. Ellie E. Schoenbaum, director of the AIDS Research Program at Montefiore Medical Center and the Albert Einstein College of Medicine in New York City. "This study wasn't perfect, but it's still an important study because it didn't reduce even gonorrhea and chlamydia, which are factors that lead to HIV."
Nonoxynol-9, marketed as "Advantage S" in the United States, is the most widely used spermicide globally and is one of two spermicides marketed in the United States. Because the substance deactivated many STDs in laboratory settings, some researchers thought it might have the same effect in humans.
This study, which was done between 1998 and 2000, looked at 1,251 sexually active women in the African nation of Cameroon. None of the women were sex workers, but all were considered high-risk because they had been treated for or had symptoms of STDs.
The women were randomized into two groups: 625 were told to use nonoxynol-9 gel with condoms (the gel was to be applied up to one hour before vaginal intercourse), and 626 were told to use condoms alone. Free condoms and gel were provided to all the women as part of the project.
Every month, the women made follow-up visits at one of 10 local pharmacies, during which they were interviewed about their sexual behavior and were asked to provide urine specimens.
The final data showed the group using the gel and condoms had a 50 percent higher risk of contracting gonorrhea than the condom-only group. The infection rate for chlamydia was similar in both groups. There were five new cases of HIV infections in the gel group and four in the condom group, not enough to assess statistically.
Some studies have found that nonoxynol-9, when used frequently, can cause tiny tears in vaginal tissue and may even facilitate the transmission of STDs.
Several explanations may account for the large number of gonorrheal infections, the authors say, including the fact that gonorrhea may have a higher transmissibility than chlamydia.
The failure of nonoxynol-9 to protect against STDs does not mean this is a fruitless avenue for further research. Scientists are still after what Barbra Richardson, research assistant professor of biostatistics at the University of Washington and author of an editorial accompanying the article, calls "a female-controlled method that's cheap and that is relatively un-intrusive and user-friendly."
The other spermicide, which is already on the market, is unlikely to undergo testing because it's so similar to nonoxynol-9. However, several smaller companies are in the process of developing microbicides, chemicals that would kill STDs. At least seven products are in the early stages of testing.
"The optimistic thing is that other microbicides are moving through the clinical pipeline to get into efficacy trials," Richardson says.
The development of such a product, which could protect against the transmission of HIV and other STDs, would be "fantastic," Richardson says.
What To Do
Condoms are still the best method to protect yourself against HIV and other STDs. The Centers for Disease Control and Prevention and the American Social Health Association have information on condoms and how to use them correctly.
Check out the Alliance for Microbicide Development for more information on this field of research.