title: Methadone inhibits rhodamine123 transport in Caco-2 cells.
abstract: This study investigated the effects of racemic methadone (MET) on P-glycoprotein (P-gp) activity in cell culture. MET showed no differential rates of passage between the basolateral to apical (B to A) and apical to basolateral (A to B) direction across Caco-2 cell monolayers in a transwell system. MET transport in either direction was not importantly influenced by the P-gp inhibitor verapamil. However, MET was a potent inhibitor (IC(50) = 7.5 microM) of rhodamine123 B to A transport across Caco-2 cell monolayers, causing a reduction to 25% of control at 100 microM MET. In this model of Caco-2 monolayers, rates of MET passage between B to A and A to B directions could not be distinguished. However, MET can inhibit P-gp activity at intraluminal concentrations that might be achieved clinically. This may lead to increased bioavailability of coadministered compounds.
authors.affiliation: Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
authors.forename: E
authors.initials: E
authors.lastname: Störmer
authors.forename: M D
authors.initials: MD
authors.lastname: Perloff
authors.forename: L L
authors.initials: LL
authors.lastname: von Moltke
authors.forename: D J
authors.initials: DJ
authors.lastname: Greenblatt
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D001692:Biological Transport; D018938:Caco-2 Cells; D004347:Drug Interactions; D006801:Humans; D008691:Methadone / Q000097:blood / Q000494:pharmacology*; D020112:Rhodamine 123 / Q000378:metabolism*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D020112:Rhodamine 123; D014700:Verapamil; D008691:Methadone