A gay man who wants to protect himself from HIV infection by using pre-exposure prophylaxis (PrEP) must take a Truvada pill once a day for at least seven days in a row to ensure it works.
That’s the conclusion of a study by researchers at the University of Colorado.
The study also found that sufficient Truvada may remain in a man’s bloodstream to protect him from HIV infection for up to 10 days after he stops using the medication. However the study warned that the 10-day period is imprecise and the researchers recommended that those on PrEP not stop taking their medication.
The study was recently reported at the International Workshop on Clinical Pharmacology of HIV and Hepatitis Therapy in Washington, D.C.
Truvada is recommended by the Centers for Disease Control and Prevention and a number of gay health organizations as a tool to help prevent HIV infection. The recommendations are based on the 2010 iPrEx study, to date the only study of the impact of Truvada on HIV infection among men who have sex with men. In that study, HIV negative men were counseled to take a daily does of Truvada, use condoms and get tested and treated monthly for sexually transmitted diseases.