Drug-permeability and transporter assays in Caco-2 and MDCK cell lines.

The human colon adenocarcinoma Caco-2 and Madin-Darby canine kidney epithelial cell lines provide in vitro tools to assess a drug's permeability and transporter interactions during discovery and development. The cells, when cultured on semiporous filters, form confluent monolayers that model the intestinal epithelial barrier for permeability, transporter and drug-interaction assays. The applications of these assays in pharmaceutical research include qualitative prediction and ranking of absorption, determining mechanism(s) of permeability, formulation effects on drug permeability, and the potential for transporter-mediated drug-drug interactions. This review focuses on recent examples of Caco-2 and Madin-Darby canine kidney cells assays for drug permeability including transfected and knock-down cells, miniaturization and automation, and assay combinations to better understand and predict intestinal drug absorption.