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What we know

Can nonoxynol-9 (N-9) prevent HIV infection?

CDC UPDATE from the National Center for HIV, STD & TB Prevention (April 97)

Although laboratory studies show that N-9 kills HIV in test tubes, available data on the efficacy and safety of N-9 spermicide to prevent sexual transmission of HIV in real life situations are inconclusive and

inconsistent. For this reason, CDC does not recommend the use of N-9 alone to prevent the sexual transmission of HIV. CDC recommends the use of male latex condoms, with or without spermicide. Nonoxynol-9 has been shown to provide some protection against two bacterial STDs, gonorrhea

and chlamydia.

What We Know about Nonoxynol-9 for HIV and STD Prevention

CDC UPDATE from the National Center for HIV, STD & TB Prevention (April 97)

Nonoxynol-9 (N-9) is a detergent-like chemical that has been used for over 30 years in vaginal products to prevent pregnancy. In the United States, N-9 is available in a variety of concentrations and formulations, including gels, creams, foams, suppositories, and film. In addition, N-9 is used in some vaginal and rectal lubricants and in the lubricant used in some pre-lubricated male latex condoms.

In laboratory and animal studies, N-9 has been shown to destroy bacteria and viruses that cause STDs, including herpes, gonorrhea, chlamydia, and HIV (the virus that causes AIDS). Even so, clinical studies (of humans in real life settings) have been inconsistent and inconclusive as to N-9's efficacy and safety. These clinical studies have used different formulations and different concentrations of N-9; making it complicated to make comparisons or draw conclusions across studies. Studies have shown that some formulations of N-9 provide women some protection against two bacterial STDs, cervical gonorrhea and chlamydia. In a review of studies, women who used N-9 without male latex condoms had a 24 to 89 percent lower risk of becoming infected with cervical gonorrhea and a 22 to 40 percent lower risk of becoming infected with cervical chlamydia than women who did not use either N-9 or condoms.

There is no evidence to date that N-9 provides protection against HIV in real life situations.

In one randomized, controlled trial among Kenyan female sex workers, no protective effect against HIV infection was observed among those using a vaginal sponge containing N-9 compared with those using a placebo suppository. However, lack of comparability between sponge and placebo users may have distorted study results.

One small observational study found that women who consistently used N-9 vaginal suppositories had a significantly lower risk of acquiring HIV infection compared with less consistent users. However, the effect of N-9 use independent of condom use could not be measured and risk of HIV infection among suppository users compared to non-users was not assessed.

An additional observational study in Zambia on condom and N-9 use among HIV discordant couples found no strong evidence that consistent use of N-9 provided protection against HIV when condoms were not used.

A recent two-year study in Cameroon conducted by Family Health International (FHI) and the Cameroon Ministry of Public Health, with partial funding from the National Institutes of Health {NIH), found that vaginal contraceptive film containing 70 mg of N-9 provided no additional protection against HIV and other STDs when provided in conjunction with male latex condoms as part of an overall HIV/STD prevention program including counseling, condom promotion and distribution, and STD treatment.

In addition, there are some questions about the safety of N-9 when used for HIV prevention. Several studies have shown that it may cause genital irritation. This is important because genital ulcers have been associated with an increased risk of HIV infection. Previous studies assessing the safety of N-9 have been inconsistent. A study conducted in the Dominican Republic found that use of suppositories containing 150 mg of N-9 once every other day did not cause genital inflammation; whereas, use once or more per day did cause genital inflammation. In addition, this inflammation increased with frequency of use. A study of the safety of N-9 film in Thailand showed that use of film containing 72 mg of N-9 two to three times per day was not associated with genital ulcers.

In the recent Cameroon clinical trial, researchers did detect a slight increase in genital ulcers among the group of women using N-9 film when compared to placebo group users. The data are preliminary and other analyses need to be done to further assess the safety issue of N-9 film. CDC will continue to review new information and to work closely with investigators for this study to determine whether or not any of our current recommendations need to be revised.

CDC Recommendations for Preventing Sexual Transmission of HIV and Other STDs

CDC recommends sexual abstinence or sexual contact only with a partner known to be uninfected as the best methods of protection against the sexual transmission of HIV and other STDs.

In addition, CDC recommends that male latex condoms be used consistently and correctly, with or without a spermicide. If for some reason it is not possible to use male latex condoms, CDC recommends using female condoms.

CDC does not recommend using spermicide alone to prevent HIV infection.

Scientific data about the effectiveness of latex condoms in preventing transmission of HIV is very clear. Male latex condoms are highly effective barriers to HIV and many other STDs when used consistently and correctly. Carefully designed studies among heterosexual couples, in which one partner is HIV positive and the other is not, demonstrate that latex condoms provide a very high level of protection against HIV.