Evaluation of documented drug interactions and contraindications associated with herbs and dietary supplements: a systematic literature review

Authors

  • H.-H. Tsai,

    1. School of Pharmacy and Graduate Institute, College of Pharmacy, China Medical University, Taichung, Taiwan
    2. Department of Pharmacy, China Medical University Hospital, Taichung, Taiwan
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  • H.-W. Lin,

    1. School of Pharmacy and Graduate Institute, College of Pharmacy, China Medical University, Taichung, Taiwan
    2. Department of Pharmacy, China Medical University Hospital, Taichung, Taiwan
    3. Department of Pharmacy Administration, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
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  • A. Simon Pickard,

    1. Department of Pharmacy Administration, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
    2. Center for Pharmacoeconomic Research, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
    3. Department of Pharmacy Practice, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
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  • H.-Y. Tsai,

    1. School of Pharmacy and Graduate Institute, College of Pharmacy, China Medical University, Taichung, Taiwan
    2. Department of Pharmacy, China Medical University Hospital, Taichung, Taiwan
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  • G. B. Mahady

    1. Department of Pharmacy Practice, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
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Hsiang-Wen (Margaret) Lin, PhD
School of Pharmacy and Graduate Institute,
College of Pharmacy, China Medical University
No. 91 Hsueh-Shih Road, Taichung 40402, Taiwan
Tel.: 886-4-22053366 ext 5151
Fax: 886-4-22078083
Email: hsiangwl@mail.cmu.edu.tw, hsiangwl@yahoo.com

Summary

Background and Aims:  The use of herbs and dietary supplements (HDS) alone or concomitantly with medications can potentially increase the risk of adverse events experienced by the patients. This review aims to evaluate the documented HDS-drug interactions and contraindications.

Methods:  A structured literature review was conducted on PubMed, EMBASE, Cochrane Library, tertiary literature and Internet.

Results:  While 85 primary literatures, six books and two web sites were reviewed for a total of 1,491 unique pairs of HDS-drug interactions, 213 HDS entities and 509 medications were involved. HDS products containing St. John’s Wort, magnesium, calcium, iron, ginkgo had the greatest number of documented interactions with medications. Warfarin, insulin, aspirin, digoxin, and ticlopidine had the greatest number of reported interactions with HDS. Medications affecting the central nervous system or cardiovascular system had more documented interactions with HDS. Of the 882 HDS-drug interactions being described its mechanism and severity, 42.3% were due to altered pharmacokinetics and 240 were described as major interactions. Of the 152 identified HDS contraindications, the most frequent involved gastrointestinal (16.4%), neurological (14.5%), and renal/genitourinary diseases (12.5%). Flaxseed, echinacea, and yohimbe had the largest number of documented contraindications.

Conclusions:  Although HDS-drug interactions and contraindications primarily concerned a relatively small subset of commonly used medications and HDS entities, this review provides the summary to identify patients, HDS products, and medications that are more susceptible to HDS-drug interactions and contraindications. The findings would facilitate the health-care professionals to communicate these documented interactions and contraindications to their patients and/or caregivers thereby preventing serious adverse events and improving desired therapeutic outcomes.

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