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Influence of Panax ginseng on Cytochrome P450 (CYP)3A and P-glycoprotein (P-gp) Activity in Healthy Participants

Authors

  • Dr Christine Y. Malati PharmD,

    1. Clinical Pharmacokinetics Research Laboratory, Pharmacy Department, Clinical Research Center, National Institutes of Health, Bethesda, Maryland
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  • Dr Sarah M. Robertson PharmD,

    1. Office of Clinical Pharmacology, Center for Drug Evaluation and Research, US Food and Drug Administration, Department of Health and Human Services, Silver Spring, Maryland
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  • Ms Jennifer D. Hunt MSN,

    1. National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
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  • Ms Cheryl Chairez BSN,

    1. National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
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  • Mr Raul M. Alfaro MS,

    1. Clinical Pharmacokinetics Research Laboratory, Pharmacy Department, Clinical Research Center, National Institutes of Health, Bethesda, Maryland
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  • Dr Joseph A. Kovacs MD,

    1. Department of Critical Care Medicine, Clinical Research Center, National Institutes of Health, Bethesda, Maryland
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  • Dr Scott R. Penzak PharmD

    Corresponding author
    1. Clinical Pharmacokinetics Research Laboratory, Pharmacy Department, Clinical Research Center, National Institutes of Health, Bethesda, Maryland
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Address for correspondence: Scott R. Penzak, PharmD, FCP, Clinical Center Pharmacy Department, Bldg 10, 1N 257, National Institutes of Health, Bethesda, MD 20892; e-mail: spenzak@mail.cc.nih.gov.

Abstract

A number of herbal preparations have been shown to interact with prescription medications secondary to modulation of cytochrome P450 (CYP) and/or P-glycoprotein (P-gp). The purpose of this study was to determine the influence of Panax ginseng on CYP3A and P-gp function using the probe substrates midazolam and fexofenadine, respectively. Twelve healthy participants (8 men) completed this open-label, single-sequence pharmacokinetic study. Healthy volunteers received single oral doses of midazolam 8 mg and fexofenadine 120 mg, before and after 28 days of P ginseng 500 mg twice daily. Midazolam and fexofenadine pharmacokinetic parameter values were calculated and compared before and after P ginseng administration. Geometric mean ratios (postginseng/preginseng) for midazolam area under the concentration-time curve from zero to infinity (AUC0-∞), half-life (t1/2), and maximum concentration (Cmax) were significantly reduced at 0.66 (0.55–0.78), 0.71 (0.53–0.90), and 0.74 (0.56–0.93), respectively. Conversely, fexofenadine pharmacokinetics were unaltered by P ginseng administration. Based on these results, P ginseng appeared to induce CYP3A activity in the liver and possibly the gastrointestinal tract. Patients taking P ginseng in combination with CYP3A substrates with narrow therapeutic ranges should be monitored closely for adequate therapeutic response to the substrate medication.

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