NIH studies link between Saquinavir and garlic pills

Blood concentrations of antiviral dropped by half

National Institutes of Health (NIH) investigators discovered that patients taking the protease inhibitor saquinavir who also ingest garlic supplements have blood levels of saquinavir that are reduced by about 50%. In a study published in December 2001 in the on-line edition of Clinical Infectious Diseases, researchers presented results showing how garlic tablets affected saquinavir levels.

The study consisted of nine healthy HIV-negative volunteers receiving doses of saquinavir for three days. The volunteers then continued with the saquinavir and took garlic caplets twice daily for three weeks. When their drug levels were analyzed, comparing baseline saquinavir with drug levels after three weeks of garlic caplets, investigators found that on average, the overall levels of saquinavir had decreased 51%, and the average maximum concentrations had fallen 54%.

Then volunteers were put on a 10-day wash-out period in which they received no garlic supplements and again were given the protease inhibitor for three days. When their saquinavir blood levels were compared, they still averaged about 35% lower than the expected baseline amount.

NIH researchers have been investigating the effects of various herbal therapies. This study’s investigators focused on garlic because it is popular as a natural remedy for high cholesterol and because both garlic and protease inhibitors share the same metabolic route, known as the CYP450 enzyme system, into the body.