Is Nonoxynol-9 an HIV Risk?

By Bob Roehr
Bay Area Reporter 23 March 2000

Lubricants containing nononxynol-9 (N-9) may increase the risk of contracting HIV and other sexually transmitted diseases when used for anal sex. This startling new research was presented last Wednesday, March 15, at Microbicide 2000, a landmark conference sponsored by the National Institutes of Health near Washington, D.C.

N-9 is a spermicide used to prevent contraception, the only one approved for use in the U.S. It also has some limited ability to kill STDs, including HIV. About three-fourths of the lubricants sold contain varying amounts of N-9. Gay men have snapped it up for use in anal sex, despite there being no clinical trials showing that N-9 is safe and effective for use in the rectum.

David Phillips, Ph.D., a senior scientist with the Population Council, uses a mouse model to test microbicides. Herpes simplex virus (HSV) is lethal to mice, so he uses it as the challenge to see if a microbicide can kill ht HSV before it can infect the mouse. When used vaginally, N-9, protects the mouse against infection.

But when he tried it in the rectum, all of the mice died. And they died faster-in four days as opposed to the normal seven to 14 days. He kept reducing the amount of virus that he used, to levels that would infect only 5 percent of normal mice with no N-9 "protection," and still they all died. What was going on?

Phillips again applied N-9 to the mice and this time, after waiting 10 minutes, he performed a lavage or douche, and looked at the samples under a microscope. He was shocked to see floating sheets of epithelial cells, the thin line of mucosal tissue that line the rectum.

One biopsy of mouse rectal tissue looked like craters of the moon under a microscope. There were "places where there was no epithelium at all, just connective tissue," said Phillips. "The N-9 had stripped the epithelial cells off of these animals." He looked again an hour later and found that the fast-repairing mucosal tissue of the mouse rectum had recovered and looked normal.

Same Results in Four Humans

The next step was to look at what happened in four human volunteers. The lab chose two commercially available products, Foreplay with 1 percent N-9 and KY Plus, with 2 percent N-9, as well as two different non-toxic carrier gels that contained no active ingredient. Each of the volunteers tried each of the products on successive days, applying a normal amount of lube, then 15 minutes later a lavage, and sent the samples off to Phillips.

"We saw striking differences with the N-9, sheets of epithelial cells, hundreds of them, in each one of the samples," he said. The response was somewhat dose related, with higher numbers of cells shed when using the KY Plus, which contains a higher concentration of N-9. The human rectum seemed to completely repair itself within 10-12 hours.

"We don't think this is a definitive study, it is only four subjects, although it is very striking that we saw the same in all four subjects," Phillips said. "It is very trouble-some," stripping off the epithelium" could lead to increased HIV transmission." He called for further study of N-9 and other products to determine their effects on the rectum.

"Phillips work is really interesting," said Dr. Kenneth Mayer, who attended the session. L He is a clinical researcher in HIV at Brown University and a members of the Gay and Lesbian Medical Association. But, "it is hard to know the clinical significance," he said.

"I think that there are enough concerns raised by the work, and anecdotal reports of irritation" when using N-9 products for anal sex, "that we can't assume that N-9 is good."

Mayer urged people to think of N-9 as a complement to condoms rather than a substitution for them. "We don't want people to say, I'm only going to use a microbicide and never try to have protected sex." He also called for further research to better understand what is going on.