title: Identification of the cytochrome P450 enzymes involved in the metabolism of domperidone.
abstract: The objective was to identify the major cytochrome P450 enzyme(s) involved in the metabolism of domperidone. Experiments were performed using human liver microsomes (HLMs), recombinant human cytochrome P450 enzymes, cytochrome P450 chemical inhibitors and monoclonal antibodies directed against cytochrome P450 enzymes. Four metabolites were identified from incubations performed with HLMs and excellent correlations were observed between the formation of domperidone hydroxylated metabolites (M1, M3 and M4), N-desalkylated domperidone metabolite (M2) and enzymatic markers of CYP3A4/5 (r2 = 0.9427, 0.951, 0.9497 and 0.8304, respectively). Ketoconazole (1 microM) decreased the formation rate of M1, M2, M3 and M4 by 83, 78, 75 and 88%, respectively, whereas the effect of other inhibitors (quinidine, furafylline and sulfaphenazole) was minimal. Important decreases in the formation rate of M1 (68%), M2 (64%) and M3 (54%) were observed with anti-CYP3A4 antibodies. Formation of M1, M2 and M3 in HLMs exhibited Michaelis-Menten kinetics (Km: 166, 248 and 36 microM, respectively). Similar Km values were observed for M1, M2 and M3 when incubations were performed with recombinant human CYP3A4 (Km: 107, 273 and 34 microM, respectively). The data suggest that CYP3As are the major enzymes involved in the metabolism of domperidone.
authors.affiliation: Faculté de Pharmacie, Université Laval, Québec, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Simard
authors.forename: V
authors.initials: V
authors.lastname: Michaud
authors.forename: B
authors.initials: B
authors.lastname: Gibbs
authors.forename: R
authors.initials: R
authors.lastname: Massé
authors.forename: E
authors.initials: E
authors.lastname: Lessard
authors.forename: J
authors.initials: J
authors.lastname: Turgeon
mesh_terms: D002478:Cells, Cultured; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis* / Q000378:metabolism*; D004294:Domperidone / Q000493:pharmacokinetics* / Q000494:pharmacology; D006801:Humans; D008862:Microsomes, Liver / Q000378:metabolism*; D025941:Protein Interaction Mapping
chemical_list: D004294:Domperidone; D003577:Cytochrome P-450 Enzyme System