In the presence of garlic supplements, blood concentrations of saquinavir decreased by about 50 percent among our study participants, explains the studys senior co-author Judith Falloon, M.D., an AIDS clinical researcher at the National Institute of Allergy and Infectious Diseases (NIAID). We saw a definite, prolonged interaction. The clear implication is that doctors and patients should be cautious about using garlic supplements during HIV therapy, she says.
For the first three days of the study, nine healthy, HIV-negative volunteers received doses of saquinavir, one of a class of drugs called protease inhibitors that are effective at slowing the progression of HIV infection. The research team drew samples from the volunteers blood to measure their baseline levels of saquinavir in the bloodstream.
Next, the volunteers took garlic caplets twice daily for three weeks. When the researchers again analyzed blood samples, the average overall levels of saquinavir had decreased 51 percent, and the average maximum concentrations had fallen 54 percent.
Even after a ten-day "wash-out" period with no garlic supplements, when the volunteers again used only the protease inhibitor for three days, their blood levels of saquinavir still averaged about 35 percent lower than the expected baseline amount.
The research papers lead author is Stephen C. Piscitelli, Pharm D., formerly with the NIH Clinical Center Pharmacy Department
Contact: Gregory Roa
NIH/National Institute of Allergy and Infectious Diseases