Via the Associated Press:
For the first time, a study shows that a drug used to treat HIV infection also can help prevent it when taken before and after risky sex by gay men. The results offer hope of a more appealing way to help prevent the disease beyond taking daily pills and using condoms, although those methods are still considered best. The study, done in France and Canada, is the first to test “on demand” use of Truvada, a pill combining two AIDS drugs, by people planning to have risky sex. The uninfected men who took it were 86 percent less likely to get HIV compared to men given dummy pills.
“That impressed me,” Dr. Scott Hammer said of the size of the benefit. He is an AIDS specialist at Columbia University in New York and heads the Retrovirus Conference going on in Seattle, where the results were discussed Tuesday. Daily Truvada pills are used now to prevent HIV infection in people at high risk for it, and studies show the drug helps even when some doses are skipped. Health officials have been leery of billing it as a “chemical condom” out of fear that people will not use the best prevention methods, but many won’t use condoms all the time or take daily pills.
The study of Gilead Science’s Truvada was led by the French national HIV research agency. Men were given fake or real Truvada and told to take two pills from two to 24 hours before sex, a third pill 24 hours later, and a fourth pill 48 hours after the first dose. The men also were given condoms and disease prevention counseling.
An important note of caution from the CDC:
Since available data suggest that men in this study were taking PrEP an average of three to four days per week, CDC cautions that researchers do not yet know if this regimen will work among MSM who have sex less frequently and would therefore be taking PrEP less often.
It is not known whether the regimen will work if taken only a few hours or days before sex, without any buildup of the drug from prior use. Studies suggest that it may take days, depending on the type of sexual exposure, for the active drug in PrEP to build up to an optimal level for preventing HIV infection.
There are also no data on how effective this regimen would be for heterosexual men and women and injection drug users or on adherence to this relatively complex PrEP regimen outside a trial setting. CDC continues to recommend only daily use of PrEP, as approved by the FDA. IPERGAY findings combined with other recent research suggests that even with less than perfect daily adherence, PrEP may still offer substantial protection if taken consistently.