Echinacea purpureaand P‐glycoprotein drug transport in Caco‐2 cells

Open Access
Publisher Website
Google Scholar
Abstract
Echinacea is widely used as a medical herbal product, but its interaction potential with the drug efflux transporter P‐glycoprotein (P‐gp) has not yet been evaluated. The interaction potential ofEchinacea purpureatowards P‐gp mediated drug transport was studied in human intestinal Caco‐2 cells. Digoxin (30 nm) was used as a substrate and verapamil as a control inhibitor. Ethanol, 0.8%, needed for herbal extraction and compatibility with the commercial products, inhibited the net digoxin flux by 18%.E. purpureainfluenced to a higher degree the B–A transport of digoxin than the A–B transport. A minor increase in net digoxin flux was observed at low concentrations ofE. purpurea, an effect anticipated to be allosteric in nature. At higher concentrations, from 0.4 to 6.36 mg dry weight/mL, a statistically significant linear dose‐related decrease was observed in the net digoxin flux, indicating a dose dependentE. purpureainhibition of P‐gp. BothVmaxandKmof the net digoxin flux, calculated to 23.7 nmol/cm2/h and 385 µm, respectively, decreased in the presence ofE. purpureain an uncompetitive fashion. Although the effects ofEchinacea purpureaon systemic P‐gp mediated drug transport are probably limited, an influence on drug bioavailability can not be excluded. Copyright © 2008 John Wiley & Sons, Ltd.