Nonoxynol-9 ineffective in preventing HIV infection

Spermicides containing nonoxynol-9 do not protect against HIV infection and may even increase the risk of HIV infection in women using these products frequently, according to a WHO report released today. The report also advises women at high risk of HIV infection against using nonoxynol-9 spermicides for contraception.

The report contains the recommendations of a meeting of experts convened by the World Health Organization (WHO) Department of Reproductive Health and Research (RHR) and the CONRAD Program* based in the Eastern Virginia Medical School. The experts also concluded that spermicides containing nonoxynol-9 do not protect against two other common sexually transmitted infections – cervical gonorrhoea and chlamydia.

Nonoxynol-9 is present in most spermicides on the market today. It has been used over the past half-century in a wide range of spermicidal products—vaginal gels, creams, foams, suppositories, sponges, and films, used alone or with other contraceptive devices, such the diaphragm. While it had been hoped that these products might reduce the risk of sexually transmitted infections, including HIV infection, they have primarily been used as methods of contraception. Estimated numbers of women of reproductive age using spermicides vary from country to country, from less than 1% in Asia to nearly 17% in some Latin American countries.

"Nonoxynol-9 clearly does not prevent HIV infection and may even favour infection if used frequently. There is an urgent need to develop a microbicide which can substantially reduce the transmission of sexually transmitted infections, including HIV, and which can be used by women," says Dr Tomris Türmen, Executive Director of Family and Community Health (FCH) at WHO.

In the 1970s and 1980s, laboratory tests showed that nonoxynol-9 could inactivate the organisms that cause gonorrhoea, chlamydial infections, and other sexually transmitted infections, as well as HIV. These findings fuelled hopes that it could be used not only for contraceptive but also for microbicidal purposes. Clinical trials conducted to date do not support these hopes.

On the contrary, two studies mentioned in the report point to an increased risk of sexually transmitted infections, including HIV infection, in women using nonoxynol-9 products. A possible reason, suggested by the findings of other studies, is that nonoxynol-9 can disrupt the epithelium, or wall, of the vagina, thereby potentially facilitating invasion by an infective organism.

The frequency of this epithelial disruption seems to depend on the intensity of use of the product—from 18% of women using the product every other day to 53% using it four times a day, in one study. "Women who have multiple daily acts of intercourse should be advised to choose another method of contraception," the experts concluded. However, they added, for women who do not use spermicides frequently and who are not at a high risk of HIV infection, spermicides that contain low doses of nonoxynol-9 are "probably safe".

Dr Henry Gabelnick, Director of CONRAD, emphasied that, "The failure of nonoxynol-9 to provide protection against HIV and other sexually transmitted infections (STIs) should not lead to the conclusion that microbicides are not possible but should instead accelerate research to find safe and effective products."

Scientists are working on some 60 promising compounds, of which 11 have reached the clinical testing stage, but lack of funds is slowing progress. Although the potential market is large—an estimated 340 million cases of curable reproductive tract infections occur each year—most cases are in resource-poor developing countries.

Regarding the use of spermicides for contraception, the report concluded that, when used alone, nonoxynol-9 is only moderately effective for pregnancy prevention but better than no contraceptive method at all. "Although far less effective than the pill or intrauterine devices or injectable or implantable contraceptives, nonoxynol-9 spermicides offer some advantages," according to Dr Tim Farley, of the Department of Reproductive Health and Research in FCH "They are readily accessible as over-the-counter products, available just about everywhere in the world and they are under the woman’s control."

Nonoxynol-9 is sometimes added to male condoms as a lubricant. The experts found no evidence that nonoxynol-9-lubricated condoms provided any more protection against pregnancy or sexually transmitted infections than condoms lubricated with silicone, used as a lubricant for the majority of condoms available in developing countries. Since nonoxynol-9 may cause some adverse effects, the experts recommended that such condoms should no longer be promoted, but noted that "it is better to use a nonoxynol-9-lubricated condom than no condom."

Nonoxynol-9 is also present in many lubricants used by people engaging in anal intercourse. Some users may be under the impression that it can also protect against HIV infection. The evidence reviewed by the experts is particularly disturbing in this regard. Studies in mice and in human subjects "revealed significant sloughing of sheets of [rectal] epithelium", the report says, suggesting that an "increased risk of infection soon after the application of products containing nonoxynol-9 seems quite likely".

While spermicides containing nonoxynol-9 remain a contraceptive option for women at low risk of HIV Infection, they are substantially less effective in preventing pregnancy than most other methods. Women at risk of HIV infection who want contraception should be informed that consistent and correct condom use is highly effective for pregnancy prevention and prevention of sexually transmitted infections, including HIV Infection.

* The CONRAD Program is a non-governmental organization administered through the Eastern Virginia Medical School in the United States. Its mission is the development of new technology for fertility regulation and prevention of sexually transmitted infections that is appropriate for developing countries.