title: Characterization of the cytochrome P450 enzymes and enzyme kinetic parameters for metabolism of BVT.2938 using different in vitro systems.
abstract: An important step in the drug development process is identification of enzymes responsible for metabolism of drug candidates and determination of enzyme kinetic parameters. These data are used to increase understanding of the pharmacokinetics and possible metabolic-based drug interactions of drug candidates. The aim of the present study was to characterize the cytochrome P450 enzymes and enzyme kinetic parameters for metabolism of BVT.2938 [1-(3-{2-[(2-ethoxy-3-pyridinyl)oxy]ethoxy}-2-pyrazinyl)-2(R)-methylpiperazine], a potent and selective 5HT2c-receptor agonist. The enzyme kinetic parameters were determined for formation of three main metabolites of BVT.2938 using human liver microsomes and expressed cytochrome P450 (CYP) isoforms. The major metabolite was formed by hydroxylation of the pyridine ring (CL(int)=27 microl/mgmin), and was catalysed by both CYP2D6*1 and CYP1A1, with K(m) values corresponding to 1.4 and 2.7 microM, respectively. The results from enzyme kinetic studies were confirmed by incubation of BVT.2938 in the presence of the chemical inhibitor of CYP2D6*1, quinidine. Quinidine inhibited the formation of the major metabolite by approximately 90%. Additionally, studies with recombinant expressed CYP isoforms from rat indicated that formation of the major metabolite of BVT.2938 was catalysed by CYP2D2. This result was further confirmed by experiments with liver slices from different rat strains, where the formation of the metabolite correlated with phenotype of CYP2D2 isoform (Sprague-Dawley male, extensive; Dark Agouti male, intermediate; Dark Agouti female, poor metabolizer). The present study showed that the major metabolite of BVT.2938 is formed by hydroxylation of the pyridine ring and catalysed by CYP2D6*1. CYP1A1 is also involved in this reaction and its role in extra-hepatic metabolism of BVT.2938 might be significant.
authors.affiliation: Preclinical R&D, Biovitrum AB, Lindhagensgatan 133, SE-112 76 Stockholm, Sweden. pawel.baranczewski@biovitrum.com
authors.forename: Pawel
authors.initials: P
authors.lastname: Baranczewski
authors.forename: Per Olof
authors.initials: PO
authors.lastname: Edlund
authors.forename: Hans
authors.initials: H
authors.lastname: Postlind
mesh_terms: D000818:Animals; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism; D004364:Pharmaceutical Preparations / Q000378:metabolism; D010879:Piperazines / Q000032:analysis; D011719:Pyrazines / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: C510632:1-(3-(2-((2-ethoxy-3-pyridinyl)oxy)ethoxy)-2-pyrazinyl)-2-methylpiperazine; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D004364:Pharmaceutical Preparations; D010879:Piperazines; D011719:Pyrazines; D011994:Recombinant Proteins; D003577:Cytochrome P-450 Enzyme System