CHAPEL HILL, N.C., March 4 (UPI) -- The drug Truvada, the only one approved for prevention of HIV infection, requires different levels in men and women to effectively prevent infection, researchers found in a recent study.
In the study, published in the Journal of Infectious Diseases, researchers at North Carolina University found men were likely protected with two doses per week, while women require a daily dose in order to be protected.
The drug was approved in 2012 by the U.S. Food and Drug Administration for daily use by people at high-risk of infection, and has significantly reduced the number of new infections in areas the drug has been made readily available.
For the study, the researchers tested for the level of DNA material present in human cells, which HIV uses to reproduce, and how much Truvada was needed to prevent HIV from infecting the cells.
The researchers then gave Truvada to 47 healthy women, taking samples of vaginal, cervical and rectal tissue, testing for levels of the drug and of DNA material present in each woman.
They found less of the drug made it to vaginal and cervical tissue than to rectal tissue. Based on a mathematical model created using data from both experiments, the researchers found while women need to take the drug every day, as recommended by the FDA, men may not need to take Truvada more than twice a week.
The researchers said they would not recommend people stop taking the drug daily, though understanding the actual amount of Truvada needed to benefit people can help improve efforts to prevent the spread of HIV.
"Our data highlight the fact that one dose does not fit all," Angela Kashuba, a researchers at the University of North Carolina, said in a press release. "In determining how best to use drugs to protect people from HIV, we need to understand where in their body they are at risk for being infected, along with the concentration of drug that is needed to protect that site from infection."