title: In vitro effects of tacrolimus on human cytochrome P450.
abstract: Tacrolimus, a potent immunosuppressive drug, is known to be metabolized predominantly in the liver by cytochrome P450 3A (CYP3A). In order to determine the potential of tacrolimus to inhibit the metabolism of other drugs, we have investigated its inhibitory effects on specific cytochrome reactions. Specific substrates for the seven cytochromes (CYPs) 1A2, 2A6, 2C9, 2C19, 2D6, 2E1 and 3A4/5 were incubated with human hepatic microsome preparations with or without specific inhibitors or tacrolimus and the metabolites were detected by high-pressure liquid chromatography (HPLC) or fluorimetric methods. All the specific inhibitors reduced or abolished the specific CYP activity. Tacrolimus had no effect on any CYP at concentrations below 1 microM, while at higher concentrations it had a mild inhibitory effect on CYP3A4 and 3A5. These observations suggest that tacrolimus is unlikely to potentiate the effect of coadministered drugs through inhibition of their metabolism in the liver.
authors.affiliation: Toxicology laboratory, C.H.U. de Bicêtre, AP/HP. 78 rue du General Leclerc, 94270 Kremlin-Bicêtre, France.
authors.forename: K
authors.initials: K
authors.lastname: Lecointre
authors.forename: V
authors.initials: V
authors.lastname: Furlan
authors.forename: A M
authors.initials: AM
authors.lastname: Taburet
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019388:Cytochrome P-450 CYP1A2 / Q000378:metabolism; D065609:Cytochrome P-450 CYP1A2 Inhibitors; D065637:Cytochrome P-450 CYP2A6; D065731:Cytochrome P-450 CYP2C19; D065729:Cytochrome P-450 CYP2C9; D019389:Cytochrome P-450 CYP2D6 / Q000378:metabolism; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D065691:Cytochrome P-450 CYP2E1 Inhibitors; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016559:Tacrolimus / Q000494:pharmacology*
chemical_list: D065609:Cytochrome P-450 CYP1A2 Inhibitors; D065690:Cytochrome P-450 CYP2D6 Inhibitors; D065691:Cytochrome P-450 CYP2E1 Inhibitors; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D007166:Immunosuppressive Agents; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D019392:Cytochrome P-450 CYP2E1; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; C104464:CYP3A protein, human; D019388:Cytochrome P-450 CYP1A2; D065637:Cytochrome P-450 CYP2A6; D065731:Cytochrome P-450 CYP2C19; D019389:Cytochrome P-450 CYP2D6; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D016559:Tacrolimus