Green Tea Catechins as Perpetrators of Drug Pharmacokinetic Interactions.

Green tea (Camellia sinensis) is a commonly consumed beverage or dietary supplement. As a natural product with a myriad of proposed health benefits, patients are likely to consume green tea while taking their medications unaware of its potential to interact with drugs and influence drug efficacy and safety. Catechins are the abundant polyphenolic compounds in green tea (e.g., (-)-epigallocatechin-3-gallate), which are reported to influence determinants of drug pharmacokinetics, such as drug solubility and the activity of drug transporters and drug metabolizing enzymes. This review summarized the results of clinical studies investigating the influence of green tea catechins on the pharmacokinetics of clinically used medications. The majority of analyses (72%) reported significant decreases (by 18-99%) in systemic drug exposure with green tea consumption (atorvastatin, celiprolol, digoxin, fexofenadine, folic acid, lisinopril, nadolol, nintedanib, raloxifene, and rosuvastatin). One analysis (6%) reported a 50% increase in drug systemic exposure (sildenafil) and for 22% of analyses drug pharmacokinetics were not affected by green tea consumption (fluvastatin, pseudoephedrine, simvastatin, and tamoxifen). For most drugs reporting an interaction, green tea catechins were proposed to decrease intestinal drug absorption by inhibiting OATP uptake (particularly OATP1A2), enhancing P-gp efflux activity or reducing drug solubility. Case reports have associated changes in drug pharmacokinetics with green tea consumption to changes in drug efficacy or safety (e.g., nadolol and erlotinib). These findings prompt the need for further research in relating evidence from existing literature to predict additional clinically important green tea-drug interactions and to provide appropriate recommendations for patients and clinicians.