Garlic Pills Dull AIDS Drug

Supplements affect protease inhibitor that slows HIV, new research shows

FRIDAY, Dec. 14, 2001 (HealthDayNews) -- Researchers have discovered that garlic supplements reduce the blood levels of a commonly used AIDS drug, raising the possibility that some people with HIV could develop resistance to the medication.

There's no evidence that garlicky foods are a problem, and it's not clear how many people with AIDS or HIV, the virus that causes AIDS, take garlic supplements. But the findings are another sign that people need to be careful when they mix prescription drugs and alternative medicine products, experts said.

Supplements "need to be taken with extreme caution," said Michael Allerton, HIV operations policy leader for Kaiser Permanente Health Plan doctors in Northern California. "No one knows what the interactions really are."

Scientists already know that St. John's wort, the herbal remedy commonly used as an antidepressant, reduces blood levels of indinavir, an AIDS drug known as a protease inhibitor. Protease inhibitors are a class of drugs used to slow down HIV.

"We took a quick look at our clinic to see what some of the more common supplements are, and garlic was way up there," said Dr. Judith Falloon, an AIDS researcher at the National Institute of Allergy and Infectious Diseases, the agency that discovered the St. John's wort interaction.

Some experts suspect that garlic may reduce cholesterol levels, which are often high in AIDS patients, Falloon said. For that reason, many patients may be taking the supplements, which are commonly found at health food stores.

In Falloon's study, researchers recruited nine healthy, HIV-negative volunteers to begin taking the AIDS drug saquinavir, which is also a protease inhibitor. People who have HIV or AIDS were not part of the study because going on and off the drug could hurt their treatment, Falloon said.

The volunteers took saquinavir for three days, then took two daily doses of garlic tablets for the next 21 days. For the last three days of the three-week period, they again took saquinavir. That way, researchers were able to test how their bodies reacted to the drug both before and after taking the supplements.

During the second round of saquinavir dosing, after almost three weeks of taking garlic supplements, the blood levels of the drug dropped by almost half compared to what they were before the volunteers began taking garlic.

It's not clear why the drug lost its ability to enter the bloodstream at the proper levels. Drug metabolism in humans is complicated, Falloon said, and can be "revved up or down" by interaction between drugs and other substances.

The findings were reported this month in an online edition of the journal Clinical Infectious Diseases.

Researchers don't know what the garlic findings mean for people who take saquinavir with other drugs. It is commonly taken by people with AIDS or HIV, as part of a multiple-drug "cocktail."

"[Protease inhibitor] is a very important class of drugs, but [saquinavir] is not the workhorse of the class," Falloon said.

Protease inhibitors and other drugs have revolutionized the treatment of AIDS since the mid-1990s, by extending people's lives and improving their quality of life. But the germs that cause AIDS can mutate and become resistant to the drugs, particularly if a person doesn't take them regularly.

Resistance is created when germs aren't killed but instead learn how to adjust to the drugs, said Allerton of Kaiser Permanente. The process is similar to that of vaccination, when a human's body is primed to fight a disease by being infected with a weak version of a germ, he said.

"Whenever blood levels go down, that means the drug is less effective, and the possibility of viral resistance goes way up," he said.

What To Do

For the latest information on HIV antiviral therapy, go to the National Institute of Allergies and Infectious Diseases or the University of California at San Francisco.

And here's the latest news on the AIDS front from AEGIS.

SOURCES: Interviews with Judith Falloon, M.D., clinical researcher, National Institute of Allergy and Infectious Diseases, Bethesda, Md.; Michael Allerton, HIV operations policy leader, Kaiser Permanente Health Plan-Northern California, Oakland, Calif.; December 2001 Clinical Infectious Diseases
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