Morning-After HIV Drugs Backed at Retrovirus Conference

Offering morning-after treatment to people potentially exposed to HIV through unprotected sex appears to ward off infection and does not increase risky sexual behavior, Brazilian researchers reported Monday at the Ninth Conference on Retroviruses and Opportunistic Infections.

Post-exposure prophylaxis (PEP) is a 28-day regimen of high doses of ZDV and 3TC. PEP is already routinely administered to health care workers who have been jabbed with needles, but using it for people possibly exposed to HIV through sex is controversial. Not only is there a lack of data on its effectiveness; some opponents fear that offering the drugs may encourage unsafe sex by providing a back-up method of staying HIV-free.

Mauro Schechter, professor of infectious diseases at the Universidade Federal do Rio de Janeiro, and colleagues gave 200 gay men who tested negative for HIV a four-day supply of PEP. The men were instructed to begin taking the drugs -- two pills a day -- if they engaged in risky sexual behaviors, and to report to the clinic within four days. Men who were deemed to have engaged in the study's criteria for risky sex -- unprotected anal, vaginal or oral sex -- were given a 24-day supply of the drugs to complete the regimen.

Over the course of two years, 73 participants used PEP 110 times. The men completed the full 28-day course 91 percent of the time. There were 11 cases of HIV infection during the course of the study: 10 among participants who did not use PEP and one that occurred despite PEP due to a drug-resistant strain of HIV. Initially, 57 percent of the men reported engaging in unprotected sex, but this number had fallen to 40 percent at the study's end. The men continued to average about six sex partners each six months.

"The numbers are small but they point in the direction that PEP can work," said Dr. Robert Janssen, director of HIV/AIDS prevention at the CDC. The agency is currently working on guidelines for PEP to be released later this year, Janssen said. The regimen's downsides include cost (about $1,000 a month for the drugs) and side effects (three-fourths of PEP users reported nausea).

"There are other things you can do to reduce your risk, such as use condoms, that are a lot more protective and effective than taking toxic drugs," Janssen said. "But in cases where prevention fails, such as a condoms breaks, this can be an effective option."

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