title: From bench to bedside: utilization of an in vitro model to predict potential drug-drug interactions in the kidney: the digoxin-mifepristone example.
abstract: Drug interactions are a common source of drug-induced toxicity. For drugs with narrow therapeutic windows, such as digoxin, an understanding of the potential mechanisms by which drugs might interact is essential to clinical practice. This article describes the utility of a renal tubular cell culture model in the prediction of drug interactions involving P-glycoprotein. Digoxin is a cardiac glycoside that undergoes active secretion in the renal tubules by the MDR1 (P-glycoprotein) drug efflux pump. Mifepristone (RU486) is a recently introduced abortifacient that is largely unstudied in terms of drug-drug interactions. The authors used an in vitro model to study the effects of mifepristone on the renal tubular secretion and cellular uptake of digoxin by Madin-Darby canine kidney (MDCK) cells. Mifepristone significantly inhibited the renal tubular secretion of digoxin (p = 0.0005), without interfering with its ability to enter the renal tubular cell. Similar results were found with the P-glycoprotein substrate vinblastine. The findings suggest that drug interactions may result if mifepristone is administered with P-glycoprotein substrates, highlighting the usefulness of this model in the study of not only common but also rare combinations of drugs.
authors.affiliation: Division of Clinical Pharmacology and Toxicology, Research Institute, Hospital for Sick Children, Departments of Pediatrics and Pharmacology, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Cindy
authors.initials: C
authors.lastname: Woodland
authors.forename: Gideon
authors.initials: G
authors.lastname: Koren
authors.forename: Shinya
authors.initials: S
authors.lastname: Ito
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000019:Abortifacient Agents / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D004077:Digoxin / Q000037:antagonists & inhibitors* / Q000378:metabolism* / Q000493:pharmacokinetics; D004285:Dogs; D005260:Female; D007684:Kidney Tubules / Q000166:cytology / Q000378:metabolism*; D015735:Mifepristone / Q000494:pharmacology*; D014747:Vinblastine / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000019:Abortifacient Agents; D015735:Mifepristone; D014747:Vinblastine; D004077:Digoxin