St. John's Wort Herb
Can Interfere With Drugs
By Maggie Fox
Reuters Health and Science Correspondent
WASHINGTON (Reuters) - St. John's wort, an herb commonly used by people to treat themselves for depression and anxiety, can interfere with a key drug used in AIDS cocktails, as well as a drug used for transplant patients, researchers said on Thursday.
They said patients taking the drug indinavir, sold by Merck under the name Crixivan, should be careful about taking St. John's wort.
``When St. John's wort and the protease inhibitor indinavir are taken together, the levels of indinavir in the blood drop dramatically,'' Dr. Stephen Piscitelli of the National Institutes of Health, who led the study, said in a statement.
This could allow the virus to come back and, worse, start developing resistance.
``Patients and health-care professionals need to be aware of this interaction,'' added Dr. Judith Falloon of the National Institute of Allergy and Infectious Diseases (NIAID), one of the institutes at the NIH. ``Most people taking medications to treat HIV infection should avoid using St. John's wort.''
It is well known that what patients eat and drink can affect the way drugs are absorbed and used by the body. For example, grapefruit juice is known to increase the effectiveness of some HIV drugs, and some of the drugs must be taken with food while others must be taken on an empty stomach.
Other research has also shown that patients who take alternative or herbal medicine often do not tell their doctors about it, in part for fear the doctors will disapprove.
``There is a misconception that herbal products like St. John's wort are safe, but this study demonstrates that there can be dangerous interactions when taken with other drugs prescribed to treat medical conditions. It is important for patients to tell their health-care providers about their use of herbal products and complementary medicines,'' Piscitelli told the Lancet medical journal, which published the study.
The NIH researchers saw reports on how St. John's wort affects the body and feared it might affect the protease inhibitor class of drugs used in treating HIV infection.
They tested eight healthy volunteers, first giving them three daily doses of Crixivan alone on an empty stomach, testing their blood levels of the drug, and then adding St. John's wort capsules.
``The results were dramatically conclusive,'' Piscitelli said. ``All the participants showed a marked drop in blood levels of indinavir after taking St. John's wort. The drop ranged from 49 percent to 99 percent.''
Protease inhibitors are often key to making HIV drug cocktails work. They can keep the virus suppressed and keep patients healthy, although they are not cured, but only if all the drugs are taken correctly.
If drug levels fall -- for instance if something like St. John's wort interferes or if the patient misses a few doses -- the virus not only comes back with a vengeance but can mutate into forms that resist the drugs.
``Resistance to indinavir can decrease the response to other protease inhibitors,'' Piscitelli said.
In a second study, Frank Ruschitzka and colleagues from University Hospital, Zurich, in Switzerland said St. John's wort can also interfere with cyclosporine, a drug used to keep patients from ``rejecting'' organ transplants.
Two patients who got heart transplants started suffering acute rejection of their hearts and had to be hospitalized after taking the herb. When they stopped taking St. John's wort, the cyclosporine levels in their bodies returned to normal and their conditions improved, Ruschitzka reported.

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