Nonoxynol-9 spermicidal lubricant

Some condoms may be advertised as being 'spermicidally lubricated'. A spermicide is a chemical substance which is used with other forms of contraception (for example, with a diaphragm). The only spermicide available in the UK is nonoxynol-9, also known as N-9.

Problems with N-9 were revealed when it was investigated as a possible microbicide. It was chosen for research on the basis of laboratory findings that it disrupted HIV and other STIs, even at very low doses, and because it was already in widespread use, including in lubricants for condoms. Animal studies confirmed that N-9 protects female monkeys against HIV-related viruses.^{1 2}

Unfortunately, N-9 causes damage to human tissue, leading to inflammation and ulceration, which is dose-related.³ It was nonetheless hoped that low-dose N-9 products, used vaginally, might be able to protect against HIV without causing excess inflammation.

However, the results of extensive clinical trials carried out on N-9 as a microbicide were clear-cut: N-9 increased HIV transmission to women who were at high risk of HIV when they used the product frequently, and appeared to have no protective effect either against HIV or other STIs when used less frequently. The most important evidence that N-9 is ineffective - or has a negative value - as a microbicide came from a randomised, placebo-controlled trial of a low-dose N-9 vaginal gel, COL-1492 that reported in 2002.⁴

This study enrolled 775 female sex workers in four countries: Benin, Ivory Coast, South Africa and Thailand, all of whom were supplied with condoms and encouraged to use them, as well as having enhanced access to diagnosis and treatment of STIs. Among these women, a further distinction was made between frequent users and less frequent users, with a threshold mean value of 3.5 uses per day.

The findings were that among less frequent users, HIV rates were not significantly different between N-9 and placebo groups. However, among more frequent users, HIV rates among N-9 users were twice the rate among placebo users. There was no effect of N-9 on rates of gonorrhoea or chlamydia infection.

A meta-analysis of eight randomised controlled trials of N-9 used vaginally assessed new HIV infections, new episodes of various STIs, and genital lesions. Comparing women using N-9 with women using a placebo or taking no treatment, there were no statistically significant differences in the risk of infection with HIV, gonorrhoea, chlamydia, cervical infection, trichomoniasis, bacterial vaginosis or candidiasis. However genital lesions were more common in the N-9 group (risk ratio 1.18, 95% confidence interval 1.02-1.36).⁵ 

Research into N-9 as a rectal microbicide was minimal and where it occurred, produced even more worrying results than in trials as a vaginal microbicide: the use of N-9 caused the rectal lining to slough off in both mice and humans, prompting a warning about the popular use of N-9-containing lubricants during anal sex. Far from protecting against HIV and other viral infections, N-9 leaves the rectum more susceptible to it.⁶

As a result of these studies, there is a consensus among organisations concerned with sexual and reproductive health that nonoxynol-9 has no role in preventing HIV and other STIs, and its use should be discouraged by anyone perceived to be at risk. At the same time, there continues to be a role for spermicides containing N-9, as readily available but moderately effective non-hormonal contraceptives, for women and couples who are at very low risk of HIV or other STIs.

It is particularly important that products containing N-9 should not be used for anal sex.

There has been resistance from condom manufacturers to calls to remove 'spermicidal lubrication' with N-9 from their products, as they perceive that it 'meets a demand' for 'extra safety' from some users. Expert opinion is that the low dose of N-9 in that lubricant does not add to their contraceptive value and might even distract women from the need for emergency back-up contraception if condoms fail. Durex have now removed spermicidal lubrication from all their condoms, but some brands still contain it.