Study Shows It May Reduce Effectiveness of Many Prescription Drugs

N E W Y O R K, Feb. 10 The Food and Drug Administration Thursday urged caution by those who use St. John’s Wort, warning that the herbal supplement may reduce the effectiveness of certain prescription drugs.
　　
　　The FDA advisory, issued to health care professionals, comes in response to a report in today’s issue of the British medical journal Lancet that suggests St. John’s Wort, as hypericum perforatum is commonly known, could make a wide range of drugs from oral contraceptives to AIDS medication to cholesterol-lowering drugs less effective.
　　“Based on [the] study and reports in the medical literature, St. John’s wort appears to be an inducer of an important metabolic pathway,"the FDA advisory said.
　　
　　“As many prescription drugs used to treat conditions such as heart disease, depression, seizures, certain cancers or to prevent conditions such as transplant rejection or pregnancy are metabolized via this pathway, health care providers should alert patients about potential drug interactions to prevent loss of therapeutic effect,"it said.
　　
　　Many doctors have already begun urging that anyone taking prescription drugs not take St. John’s Wort.
　　
　　“We’re very worried,"says Dr. Stephen Piscatelli, coordinator of the Pharmacokinetics Laboratory at the National Institutes of Health Clinical Center and the lead investigator of one of the two research letters published today.
　　
　　“This is seminal in terms of how we regulate herbal products,"adds David Flockhart, associate professor of medicine and pharmacology at Georgetown University.
　　
　　“It means that St. John’s Wort ought to be regulated,"Flockhart says. “And a lot of people aren’t going to like me for saying that, but you’ve got an herbal here that has a major drug interaction"　　
　　 One industry analyst estimated that sales of St. John’s Wort last year were over $200 million.
　　AIDS, Heart Treatments Affected
　　Piscatelli’s study focused on eight AIDS patients taking the protease inhibitor indinavir. When the subjects took both indinavir, used commonly for the treatment of AIDS, and St. John’s Wort, researchers found less of the AIDS drug in the patients blood. Having a low level of the drug in an AIDS patient’s body is a common cause of resistance and treatment failure.
　　
　　Researchers in Zurich, Switzerland, also published a letter in which they detail the cases of two heart transplant recipients who rejected their new organs both after taking St. John’s Wort.
　　
　　The supplement apparently lowered the level of cyclosporine, an anti-rejection medication in the blood. Withdrawal of St. John’s Wort allowed the drug to do its job; no further episodes of rejection occurred.
　　
　　Scientists are concerned about the implications of this research. They believe St. John’s Wort makes drugs move through the body more quickly than they otherwise would, a process that keeps them from being effective.

50 Drugs Could be Affected
　　About 50 drugs are circulated through the body in the same way that indinavir and organ-rejection drugs are including cholesterol-lowering drugs and oral contraceptives.
　　
　　“I think people should just stay away from St. John’s Wort until we [know how safe it is],"says Dr. Curt Furberg, professor of public health science at Wake Forest University School of Medicine. “I think they’re taking an unnecessary risk when they take these agents with prescription drugs. 　　
　　Even the trade association for natural medicine manufacturers is worried. “If people are using St. John’s Wort, they should not be taking prescription medication without checking with their doctor or pharmacist first,"says Mark Blumenthal, founder and executive director of the American Botanical Council.
　　
　　“The only problem is that doctors and pharmacists may not even know about these latest findings,"he said. “The bottom line is: When in doubt, don’t use it." 　　
　　St. John’s Wort is widely used in Germany as a treatment for depression and anxiety. Some U.S. physicians have started recommending it to patients and report that the herb has shown effectiveness in stemming depression and anxiety.

Consumers Beware
　　
　　Consumers should be careful about all herbal medicines and what they contain, researchers say.
　　
　　“My wife bought tea recently and I saw St. John’s Wort was in it,"says Dr. Jerome Lasker, professor of Biochemistry at Mount Sinai Medical Center. “It’s everywhere." 　　
　　In light of the latest findings, Dr. Robert Califf, who is conducting a trial testing the efficacy of St. John’s Wort, is considering changing his experiment design to see whether taking the supplement may be changing drug levels and interactions in his subjects.
　　
　　“We’ll have to look and see if it would be worthwhile to measure drug levels [in our subjects] "I suspect it will be,"he says. “These herbal medications shouldn’t be taken for granted." 　　
　　From ABCnews