Clinically Relevant Herb-Drug Interactions: A 30-year Historical Perspective

Join Bill J. Gurley, Ph.D., a leading researcher in dietary supplement safety and efficacy, for an exploration of the rise of botanical dietary supplements over the past 30 years and their potential for clinically significant herb–drug interactions. This session will highlight key botanicals linked to pharmacodynamic and pharmacokinetic mechanisms and offer insights into their implications for safe clinical practice.What You Will Learn:
The Dietary Supplement Health and Education Act, a legislative measure

ushering in a novel class of complementary healthcare products known as dietary supplements, had its 30th anniversary in October 2024. Over this 30-year period, dietary supplement usage evolved from a few hundred products made up mostly of vitamins, minerals, and select botanical extracts to more than 75,000 single and multi-ingredient products that are now regular staples in the American healthcare system and used by half of all U.S. consumers.

One of the fastest-growing segments of the dietary supplement market during this 3-decade interval has been those products formulated with botanical extracts. Coincident with the growing popularity of botanical dietary supplements (BDS) has been their concomitant ingestion with conventional prescription medications.When taken with prescription drugs, BDS may give rise to clinically significant herb–drug interactions (HDI).

Pharmacodynamic HDI describe interactions between phytochemicals and conventional medications at the drug receptor level, while pharmacokinetic HDI stem from phytochemical-mediated induction and/or inhibition of human drug metabolizing enzymes and/or transporters. This focus session will summarize BDS identified over the last 30 years that pose clinically relevant HDI and whose mechanisms are either pharmacodynamically or pharmacokinetically mediated.

Teacher Name:  Bill J. Gurley, Ph.D.

Teacher Bio:  Bill J. Gurley is a leading researcher in the field of dietary supplement safety and efficacy, with nearly 30 years of experience in basic and clinical research. He currently serves as Professor and Principal Scientist at the National Center for Natural Products Research (NCNPR) at the University of Mississippi, where he co-directs the Clinical Research Facility and chairs the university’s Institutional Animal Care and Use Committee.  Before joining NCNPR in 2019, he was a Professor of Pharmaceutical Sciences at the University of Arkansas for Medical Sciences (UAMS) College of Pharmacy, where he also served as Vice-Chair of the Department of Pharmaceutical Sciences and Chair of the Institutional Animal Care and Use Committee.

Dr. Gurley’s research has played a critical role in shaping regulatory policies on dietary supplements. His work on Ephedra-containing supplements contributed to the FDA’s 2004 decision to remove these products from the U.S. market. He was also the first investigator to systematically evaluate the herb-drug interaction potential of popular dietary supplements and assess their clinical relevance. His research team was the first to document the serious clinical implications of herb-drug interactions involving St. John’s wort, influencing how such interactions are understood and managed.

His primary research interests include clinical pharmacokinetics, herb-drug interaction mechanisms, safety evaluation of multi-component botanical dietary supplements (BDS), phytochemical modulation of human drug-metabolizing enzymes and transport proteins, human phytochemical disposition, and BDS dosage form performance. These efforts have resulted in more than 200 peer-reviewed scientific publications.

Dr. Gurley is an expert panel member for the United States Pharmacopeia’s Dietary Supplements division, an advisor to the American Botanical Council, and a co-editor of the American Herbal Products Association’s Botanical Safety Handbook. He also serves on the editorial boards of Clinical Pharmacology & Therapeutics, Phytomedicine, HerbalGram, and Clinical Therapeutics.

He earned a B.S. in Chemistry from Tennessee Technological University, followed by a B.S. in Pharmacy and a Ph.D. in Pharmaceutics from the University of Tennessee Health Science Center.

Monthly online workshops focusing on mentorship, business, clinical, and community herbalism to foster professional development in the herbalism community.

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