A new combination HIV/AIDS pill called Truvada may offer big protection when users take the prophylactic every day. The pill, which is a combination of two other antiretroviral drugs, emtricitabine (Emtriva) and tenofovir (Viread), was tested in over 2,500 men who were considered to be at high risk for HIV/AIDS infection.
The numbers suggest that Truvada offers an average risk reduction of about 44%. But when separating out those who took the pill most faithfully, this number rose to almost 73% for people who took it 90% of the time.
The new study followed 2,500 men in 11 countries. All participants were either gay or identified themselves as transgender women (but are biologically men). All were determined to be at exceptionally high risk for contracting HIV/AIDS in their daily lives. Half the participants were given Truvada and the other half were given placebo; both groups received counseling on safe sex and 500,000 condoms were doled out over the study’s 1.2 year period.
At the study’s end, 36 people who took Truvada contracted HIV/AIDS, while 64 people in the placebo group contracted the disease. These numbers suggest that Truvada offers an average risk reduction of about 44%. But when separating out those who took the pill most faithfully, this number rose to almost 73% for people who took it 90% of the time. The researchers were able to verify how often the participants were taking the pill by looking at levels of the drug in blood samples.
One reason that participants were less likely to take the drug every day may have had to do with the way the pills were introduced. The researchers told participants they would either be receiving placebo or an "active drug having no proven benefit". This description may not have been the most enticing lead-in. And, as the team points out, in the future additional research and creative promotion may make people more eager to comply with the pill’s instructions for daily use. And of course, more studies will be needed to determine whether the drug works equally well for women.
The CDC is currently devising guidelines for the distribution of the drug. They point out that it should not be thought of as "the first line of defense against HIV", and should always be used in conjunction with other known methods. For more information on Truvada, see the CDC’s fact sheet: http://www.cdc.gov/nchhstp/newsroom/PrEPforHIVFactSheet.html
The research was conducted by a team at Gladstone Institute of Virology and the University of California, San Francisco, and published in the November 25, 2010 issue of The New England Journal of Medicine.