Pills as a Prevention Tool?

The success of antiretroviral medications in controlling HIV disease has been the hallmark of the last decade of the AIDS pandemic, but new studies show that some of the medications may not only treat HIV disease, they may actually prevent HIV infections in the first place. Human studies are already being conducted to gauge the effectiveness of Gilead Sciences' nucleotide analog Viread in preventing HIV infections. But a new monkey study shows that Viread when combined with Gilead's nucleoside analog Emtriva (sold together in the combination pill Truvada) was 100% effective in blocking rectal HIV infections, even in animals exposed to the virus twice daily for a week. The study data are so encouraging that the human trials have been expanded to include both anti-HIV medications and enlarged to enroll more participants. It's not yet clear who might best benefit from Truvada preexposure prophylaxis'although sexually active gay men would likely be an early target group'or even how often the drugs would need to be taken--some scientists say a once-weekly dose may be possible. And there are concerns that a preventative pill could fuel an explosion in unprotected sex among high-risk individuals. But even in light of these unanswered questions and potential pitfalls, study results so far have produced a rare sense of enthusiasm among notoriously cautious AIDS experts. 'This is the first thing I've seen at this point that I think really could have a prevention impact,' says long-time federal AIDS researcher Thomas Folks. 'If it works, it could be distributed quickly and could blunt the epidemic.'