On Monday morning, at the Microbicides 2002 meeting in Antwerp, Belgium, Dr David Wilkinson of the University of South Australia presented a meta-analysis of clinical trials, including one that is not yet published, that had looked at nonoxynol-9 (N-9) as a possible microbicide to prevent HIV and sexually transmitted infections (STIs) in women.
This was the first public presentation of this work, which set out to get as close as possible to firm answers to three questions. Does nonoxynol-9 have any effect on HIV transmission from men to women? Does it have any effect on other sexually transmitted infections? Does it have an effect on genital ulcers/lesions?
Of thirteen trials that had tested nonoxynol-9 products, two had to be excluded because they didn’t look at relevant outcomes and one was excluded because of poor trial design. This left nine trials, reported in ten publications, involving some 5,000 women. While a variety of different products had been used, with different amounts of N-9, there turned out to be no variation in the findings with dose or formulation between those studies.
The conclusion is that N-9 provides no protection against HIV or other STIs, although if there is any extra risk it is small. However, there is evidence of harm, described in another session as vulvar ulcers, vulvitis and irritative symptoms. N-9 therefore cannot be promoted for HIV or STI prevention.
Results are awaited from a clinical trial which is evaluating N-9 as a spermicide. If it turns out that it is of limited use in this respect too, then it is likely that there will be a push to take it off the market.
It appears that the number of women who rely on N-9 for contraception is very limited, estimated at around 2% of women using public family planning services in the USA and around 1% of their counterparts in sub-Saharan Africa. However, many more women – and men – are exposed to N-9 in small doses within the lubricants on condoms.
In another session, on Tuesday morning, Dr Connie Celum from the University of Washington presented evidence from a small safety trial of N-9 for anal sex, carried out with the help of gay male volunteer couples, 10 HIV positive and 25 HIV negative.
Her study, carried out as part of the NIH HIVNET programme before the results of larger trials in women showed that N-9 was likely to do more harm than good, was set against the background of a survey in 1995-97 of gay men in an HIV study cohort, of whom 80% used a lubricant 80% of the time, with three quarters of those lubricants containing N-9 and many men reporting that they deliberately looked for lubricants which did so.
She found limited evidence for extra irritation where N-9 was used, although the main finding from her study was that one week of placebo used before N-9 was used was not enough to be certain of the meaning of symptoms reported by volunteers, and biopsies showed only very subtle changes. Also, the formulation of N-9 used in her study wasn’t a particularly good lubricant, since it had been chosen more with a view to standardising the doses men were exposed to.
Despite the limitations of her findings, she was convinced that a public information campaign is needed, to warn gay men not to use lubricants containing N-9. What is not clear, however, is how much change has already taken place with discussion of the risks of N-9 in gay media and HIV information materials.