# St.Johns Wort May Interfere with Medicines: Many Common Drugs Curtailed by Popular He



## JeanG (Oct 20, 1999)

The URL for this article is: http://www.healthscout.com/cgi-bin/WebObje...ap=55&id=104882 St. John's Wort May Interfere With Medicines Many common drugs curtailed by popular herb By Julia McNamee Neenan HealthScout Reporter THURSDAY, Nov. 2 (HealthScout) -- St. John's wort, the popular herbal supplement said to ease depression, dangerously interferes with about half of the most common medications used today, claims new research. The over-the-counter supplement speeds up digestion of the drugs so they pass through the body quickly, often without having the effect for which they were prescribed, says B.J. Gurley, an associate professor of pharmaceutical sciences at the University of Arkansas for Medical Sciences. Drugs affected by St. John's wort include birth control pills, some cholesterol-lowering medicines, many heart medications and antifungal drugs, Gurley says. Earlier this year the U.S. Food and Drug Administration warned that the supplement might block the activity of protease inhibitors used to treat people with AIDS. "What this tells you is that, if you're taking St. John's wort on a long-term basis in conjunction with conventional medication, the efficacy of those conventional medications is severely curtailed," Gurley says. Sales of St. John's wort passed $400 million in 1998, according to the FDA, making it one of the most popular supplements sold. Before medicines are put on the market, they are subjected to rigorous testing to determine whether they react with other drugs, says Dr. Benjamin G. Druss, an assistant professor of psychiatry and public health at Yale University's School of Medicine. But herbal supplements such as St. John's wort are considered dietary supplements and thus not regulated by the government. That's a significant loophole, Druss says. "The bottom line is that, just as these treatments are  potentially effective, so are they potentially dangerous, just like any other substance someone ingests into the body," he says. The body can digest or metabolize medicines along any of four pathways, Gurley says. St. John's wort speeds up the digestion process along the pathway responsible for digesting about 50 percent of the most common medicines, the study says. Gurley presented his findings yesterday to the American Association of Pharmaceutical Scientists, meeting in Indianapolis. But continuation of Gurley's research suggests that two of the other pathways similarly are affected by St. John's wort, which would raise the number of common medicines affected to 75 percent, he says. The expanded list includes traditional antidepressants, and Gurley says that could mean that people with depression could be badly hurt by piggybacking St. John's wort and prescribed medicines. People who've had organ transplants also should be wary of the supplement, Gurley says. St. John's wort can compromise the effectiveness of cyclosporine, a drug used to suppress the immune system's natural tendency to reject a transplanted organ, he says. Two people who received kidney and kidney-pancreas transplants suffered great setbacks when they began taking St. John's wort, Gurley says. In one of the cases, it took doctors more than a month to determine what was causing a woman's low levels of cyclosporine, despite repeated increases of the medication's dosage. The woman has since rejected the kidney and is now on dialysis, and her pancreas also is in bad shape, Gurley says. Stephen Piscitelli, who has conducted his own research into the metabolic effects of St. John's wort at the National Institutes of Health, agrees with the need for caution. "This specific herb can have serious drug interactions," Piscitelli says. "Just because something is natural doesn't mean something is safe." To measure the effect of St. John's wort on the metabolism of drugs, Gurley analyzed how long the body holds onto the drug midazolam. He gave 12 college students 300 milligrams of St. John's wort three times a day for 28 days and then gave them an oral dose of midazolam. An hour later, tests showed that the students' bodies had metabolized the midazolam more than twice as quickly as they had in tests before the St. John's wort regimen began, he says. By contrast, when the students were put on similar regimens of garlic and ginseng, the study says, metabolism of the medicine was not affected. Researchers remain unsure just what components of herbs are responsible for their different effects. Most herbs are a composite of various plant chemicals, and many of those have strong medicinal effects, Gurley says. Plus some herb mixtures contain elements such as lead and mercury, he says, so you are concocting combinations of medicines with truly unknown consequences. What To Do People need to be as frank as possible when talking with their doctors, experts say, revealing everything they're taking -- supplements as well as prescribed medications -- to avoid problems. And doctors need to educate themselves about supplements so they can ask the right questions, Druss says. To read more about St. John's wort, visit the National Institutes of Health and the National Institute of Mental Health online. Or, you may want to read previous HealthScout articles on St. John's wort and other herbal supplements.


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