The C.A.M. Report
Complementary and Alternative Medicine: Fair, Balanced, and to the Point
  • About this web log

    This blog is intended as an objective and dispassionate source of information on the latest CAM research. Since my background is in pharmacy and allopathic medicine, I view all CAM as advancing through the development pipeline to eventually become integrated into mainstream medical practice. Some will succeed while others fail. But all are treated fairly here.

  • About the author

    John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at www.Vicus.com, a complementary and alternative medicine website.

  • Common sense considerations

    The material on this weblog is for informational purposes. It is not medical advice or counsel. Be smart, consult your health professional before using CAM.

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    Potential for berberine to cause drug interactions

    Berberine is used to treat gastrointestinal infections, diabetes, high blood pressure, and cholesterol. Many studies report interactions between berberine-containing products and cytochrome P450, but little is known about whether berberine alters CYP activities in humans.

    Researchers at the Xiang Ya School of Medicine, in the People’s Republic of China, studied the effects of berberine on a series of drugs and P450 enzymes after repeated dosing.

    First, the details.

    • Healthy men were assigned to take each treatment in random order — crossover design.
    • After 2 weeks of berberine 300 mg 3 times daily by mouth, dextromethorphan (Benylin), losartan (Cozaar), and caffeine were used to evaluate enzyme activities of CYP3A4, 2C19, 2D6, 2C9, and CYP1A2, respectively.

    And, the results.

    • CYP2D6 activity decreased significantly as urinary levels of dextromethorphan/dextrorphan increased.
    • The losartan/E-3174 ratio increased significantly after berberine administration, indicating a decrease in CYP2C9 activity.
    • CYP3A4 activity was significantly inhibited as midazolam levels increased.
    • Compared to placebo, with berberine there was a significant delay in the time to maximum blood levels and elimination of midazolam from the body.
    • There were no other statistically significant differences.

    The bottom line?

    The authors concluded, “Repeated administration of berberine (300 mg, 3 times daily by mouth) decreased CYP2D6, 2C9, and CYP3A4 activities. Drug-drug interactions should be considered when berberine is administered.”

    Careful when taking berberine at the same time as taking dextromethorphan, losartan, and midazolam.

    8/29/11 20:57 JR

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