Trial shows nonoxynol 9 efficacy is questionable
Trial shows nonoxynol 9 efficacy is questionable
Disagreement exists on its value
The first "real life" controlled trial of the spermicide nonoxynol 9 (N-9) has found that its efficacy is questionable in reducing the rate of HIV, gonorrhea, or chlamydia in prostitutes.1 (See related article, p. 118, on the specifics of the study.) Researchers familiar with the spermicide disagree, however, about whether those results mean N-9 should no longer be recommended at all to prevent HIV. Although most experts agree the product should not be used alone, some authorities are still recommending it be used with either a male or female condom to provide a possible added measure of protection against HIV and other sexually transmitted diseases because N-9 is the only product of its kind on the market.
"The main thing we're trying to say about our study is that it raises serious doubts about how effective N-9 is in terms of disease protection," says Nash Herndon, spokesperson for Family Health International (FHI) in Research Triangle Park, NC, which conducted the study. "There are some women who cannot convince their partners to use condoms, and so for many of these women, they may use N-9 as their primary defense. And they need to be aware of the fact that there is this doubt about how much protection they are getting. The study underscores the need for additional products, and it also should underscore for them that they are at greater risk than they might have assumed."
Herndon says it is possible the N-9 film was not effective against HIV, but that other N-9 products might be effective. The film used in the study contained 70 mg of the product, whereas some gels contain more than 150 mg of N-9. Next month, FHI will start a new trial to determine how well an N-9 product prevents chlamydia and gonorrhea.
"As an organization, we certainly feel we have not answered all questions," Herndon says. "There does need to be more research to look at N-9 products to see what they can do for protection."
No better, no worse
The only good news from the latest study is that N-9 did not appear to enhance infection with HIV, he adds.
"That was a real concern," Herndon says. "That was one of the things the study looked for. There has been a longstanding theoretical concern that because it irritates tissue lining, that it may in fact be making matters worse. So we did not see it make matters better, but at the same time we didn't see it was making anything worse."
Penelope Hitchcock, DVM, chief of the STD branch of the National Institute of Allergy and Infectious Diseases in Bethesda, MD, says the study is important because it is the first randomized, controlled trial of N-9's efficacy against HIV.
"This is a placebo-controlled trial," she says. "The study was really executed in a flawless way. I think there are many published accounts in the literature, and in each case, there are problems with the study that make it very difficult to interpret the findings."
Like Herndon, Hitchcock says it is possible the N-9 did not protect against HIV and other STDs in the study because it wasn't used properly.
"This is one particular product," she says. "This is a film containing 70 mg of nonoxynol 9. In order for the nonoxynol 9 to work, the film has to melt based on the warmth and moisture in the vagina, and then release the active ingredient. You cannot generalize from one formulation or product to the next. Another product might have 150 mg of nonoxynol 9 and it might be in a gel formulation, which was active immediately. So each of these products needs to be looked at by itself. I think it is inappropriate to generalize beyond this particular product."
Hitchcock adds that she is reluctant to draw "strong conclusions" from the study because the women may have not accurately reported how often they used condoms and/or N-9.
"All this hinges on whether the women actually used the film and condoms as they said," she says.
Hitchcock says she also is concerned because N-9 appears to cause vaginal irritation, which may actually increase the risk of HIV and other STDs. In the Cameroon study, women who used N-9 film were more likely to have vaginal lesions. There were 42.2 lesions per 100 woman-years among women using N-9 compared to 33.5 lesions per 100 woman-years among women using placebo film. Although rates of HIV were similar among both groups of women, Hitchcock says vaginal lesions appeared to have increased the risk of HIV in previous studies.
"I think we don't know at this point in time whether the product is safe," she says. "We know that it causes ulcers and irritation in the vagina. We know a sexually transmitted disease causes the same kind of ulcer and irritation, and that it increases the risk of HIV infection. So at this point in time, I think the answer about safety is unknown, and we need to do the clinical trials."
But Michael Rosenberg, MD, MPH, president of Health Decisions Inc. in Chapel Hill, NC, says he is concerned that the latest study will be "misinterpreted."
"I heard something in the news that said that N-9 does not work against HIV," he says. "And that's not what the study was about. The study looked at women who used condoms, and women who used condoms plus spermicide. So it was really a study of what extra protection spermicides afford beyond the use of condoms. And that's an important distinction."
Rosenberg says the study is less about the efficacy of N-9 against HIV than about the fact that condoms do work.
"We've already known that quite well for some time," he says.
Based on the latest study, what should women do about using N-9? Herndon stops short of recommending that N-9 not be used at all for protection against HIV.
"Should someone stop using it?" he asks. "The main thing is to know that it may not be as protective as we once thought. But if you're someone who is using a diaphragm and this product, I see no reason to stop doing that. If you're using [N-9] and that's your only protection against disease, and you're in a risky situation, then the real strong message ought to be to convince that man to use a condom."
Hitchcock discourages the use of N-9.
"My generic recommendation is, in the absence of evidence, I think we should not be recommending products," she says. "I don't think we have enough evidence about nonoxynol 9 one way or another to recommend its use. I would not put nonoxynol 9 in my vagina at this point in time, and I wouldn't recommend a woman do that."
Spermicide alone not recommended for HI
Rosenberg says there is "some suggestive evidence" that N-9 may help prevent HIV and other STDs. "I would probably recommend using it. I think N-9 is better than nothing," he says.
The Centers for Disease Control and Prevention in Atlanta has recommended since last April that "male latex condoms be used consistently and correctly, with or without a spermicide." If it is not possible to use male condoms, the agency recommends that a female condom be used. CDC does not recommend that spermicide alone be used to protect against HIV.
"Our recommendation is [to use] condoms, with or without nonoxynol 9, [but] we don't recommend spermicides alone," says Katherine Stone, MD, assistant chief for science in the epidemiology and surveillance branch in the division of STD prevention at CDC. "There's really no evidence that using a spermicide gives you any extra protection in addition to a condom. Condoms do occasionally break, and people want to have a backup method, but it's not clear whether spermicides alone will work for HIV."
(Editor's note: More information about N-9 is available on FHI's Web site at www.fhi.org.)
Reference
1. Roddy RE, Zekeng L, Ryan KA, et al. A controlled trial of nonoxynol 9 to reduce male-to-female transmission of sexually transmitted diseases. New Engl J Med 1998; 339: 504-510.
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