Nonoxynol 9 has been used as a chemical spermicide since the 1950s. This chemical compound, through its disruption of epithelial cells, bacteria and viruses, also acts in vitro against a variety of pathogens, including Chlamydia trachomatis, Neisseria gonorrhoeae and Treponema pallidum. Evidence from in vitro studies suggests that nonoxynol 9 is able to inactivate the human immunodeficiency virus (HIV); however, clinical results have been conflicting. Roddy and colleagues performed a randomized, controlled trial to determine if nonoxynol 9 used before intercourse could reduce the rate of sexually transmitted diseases (STDs), including HIV, among women.

Study participants were HIV-seronegative female sex workers in Cameroon who were between 18 and 45 years of age and averaged at least four sexual partners per month. They were given a vaginal film that contained 70 mg of nonoxynol 9 or a placebo film that was identical in appearance. The 5 × 5-cm film was inserted vaginally before intercourse and dissolved in two to five minutes. In addition, all women were given plain latex condoms for their partners to use. Both the film and the condom were recommended for use with each sexual encounter.

The women were instructed to keep a log for recording the frequency of vaginal, oral and anal intercourse. They were also to include use of antibiotics, receipt of injections and use of other vaginal agents such as douches. Each woman also underwent monthly HIV testing, examination for genital and cervical ulcerations, and DNA-probe tests for gonorrhea and Chlamydia, which were performed by the researchers. The patients were also counseled again at each visit regarding the correct and continuous use of the vaginal film and the condoms.

A total of 1,170 women were randomized into the study and ultimately 941 completed the 12 months of follow-up. The average age of the participants was 26 years, and the prevalence of STDs was similar at baseline in both the control and the treatment groups. Compliance with the use of condoms and vaginal film ranged from 63 to 86 percent. During the study, there were 94 HIV seroconversions, including 48 in the treatment group and 46 in the placebo group. There were 111 cases of gonorrhea and 81 cases of Chlamydia infection in the placebo group compared with 114 cases of gonorrhea and 79 cases of Chlamydia infection in the nonoxynol 9 group. The rate of genital lesions in the treatment group was 42.2 percent compared with 33.5 percent in the placebo group. However, the presence of genital ulcerations did not predict HIV seroconversion, as has been reported in other studies.

The authors conclude that nonoxynol 9 does not provide additional protection from gonorrhea, Chlamydia or HIV infection beyond that provided by condoms. Furthermore, they state that there is a compelling need to develop better barrier methods that can be controlled by women for protection against sexually transmitted infections.