title: Comparison of in vitro P-glycoprotein screening assays: recommendations for their use in drug discovery.
abstract: The ATP-dependent drug efflux pump P-glycoprotein (P-gp) affects the absorption and disposition of many compounds. P-gp may also play role in clinically significant drug-drug interactions. Therefore, it is important to find potential substrates or inhibitors of P-gp early in the drug discovery process. To identify compounds that interact with this transporter, several P-gp assays were validated and compared by testing a set of 28 reference compounds, including inhibitors of cytochrome P450 3A4 (CYP3A4). The assays included in silico predictions, inhibition assays (based on cellular uptake of rhodamine-123 or calcein AM), and functional assays (ATPase activity assay and transcellular transport assay, the latter for a subset of compounds). In addition, species differences were studied in an indirect fluorescence indicator screening assay and test systems expressing porcine, mouse, or human P-gp. Our results suggest that several P-gp assays should be used in combination to classify compounds as substrates or inhibitors of P-gp. Recommendations are given on screening strategies which can be applied to different phases of the drug discovery and development process.
authors.affiliation: F. Hoffmann-LaRoche Ltd., Pharmaceuticals Division, CH-4070 Basel, Switzerland.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Schwab
authors.forename: Holger
authors.initials: H
authors.lastname: Fischer
authors.forename: Ali
authors.initials: A
authors.lastname: Tabatabaei
authors.forename: Sonia
authors.initials: S
authors.lastname: Poli
authors.forename: Jörg
authors.initials: J
authors.lastname: Huwyler
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis* / Q000037:antagonists & inhibitors / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D005452:Fluoresceins; D005456:Fluorescent Dyes; D006801:Humans; D007202:Indicators and Reagents; D051379:Mice; D008958:Models, Molecular; D012235:Rhodamines; D013045:Species Specificity; D013552:Swine
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D012235:Rhodamines; C085925:calcein AM; D000251:Adenosine Triphosphatases