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Updated: Aug 6, 2026

Measuring Rates of Herbicide Metabolism in Dicot Weeds with an Excised Leaf Assay
Published on: September 7, 2015
Herb-drug interactions: focus on pharmacokinetics
1PsychoFarmacology Consulting Services, College Park, MD, USA. alkaloid@jerrycott.com
Abstract:
Recent literature regarding drug-drug, herb-drug, and food-drug interactions must not be ignored; nor can they always be taken at face value. Studies have shown that St. John's wort (SJW) (Hypericum perforatum) can reduce plasma levels of indinavir, cyclosporin, digoxin, and possibly other drugs as well. Current knowledge regarding the metabolism of these medications suggests that the cytochrome P450 (CYP) drug metabolizing enzyme systems cannot account for all these effects. It has been reported that the P-glycoprotein (Pgp) transmembrane pump is also induced by SJW. Medications that are substrates of both CYP 3A4 and Pgp are of particular concern and may pose special interaction risks when combined with certain foods or botanical products such as SJW.
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