title: Identification of metabolic pathways and enzyme systems involved in the in vitro human hepatic metabolism of dronedarone, a potent new oral antiarrhythmic drug.
abstract: The in vitro metabolism of dronedarone and its major metabolites has been studied in human liver microsomes and cryopreserved hepatocytes in primary culture through the use of specific or total cytochrome P450 (CYP) and monoamine oxidase (MAO) inhibitors. The identification of the main metabolites and enzymes participating in their metabolism was also elucidated by using rhCYP, rhMAO, flavin monooxygenases (rhFMO) and UDP-glucuronosyltransferases (rhUGT) and liquid chromatography/tandem mass spectrometry (LC/MS-MS) analysis. Dronedarone was extensively metabolized in human hepatocytes with a metabolic clearance being almost completely inhibited (98 ± 2%) by 1-aminobenzotriazole. Ketoconazole also inhibited dronedarone metabolism by 89 ± 7%, demonstrating the crucial role of CYP3A in its metabolism. CYP3A isoforms mostly contributed to N-debutylation while hydroxylation on the butyl-benzofuran moiety was catalyzed by CYP2D6. However, hydroxylation on the dibutylamine moiety did not appear to be CYP-dependent. N-debutyl-dronedarone was less rapidly metabolized than dronedarone, the major metabolic pathway being catalyzed by MAO-A to form propanoic acid-dronedarone and phenol-dronedarone. Propanoic acid-dronedarone was metabolized at a similar rate to that of N-debutyl-dronedarone and was predominantly hydroxylated by CYP2C8 and CYP1A1. Phenol-dronedarone was extensively glucuronidated while C-dealkyl-dronedarone was metabolized at a slow rate. The evaluation of the systemic clearance of each metabolic process together with the identification of both the major metabolites and predominant enzyme systems and isoforms involved in the formation and subsequent metabolism of these metabolites has enhanced the overall understanding of metabolism of dronedarone in humans.
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Klieber
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Arabeyre-Fabre
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Patricia
authors.initials: P
authors.lastname: Moliner
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Marti
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Martine
authors.initials: M
authors.lastname: Mandray
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Robert
authors.initials: R
authors.lastname: Ngo
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Ollier
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Brun
authors.affiliation: SANOFI-AVENTIS Recherche & Development Disposition, Safety and Animal Research Scientific Core Platform, Drug Disposition Domain 371 Rue du Professeur Joseph Blayac, 34184 Montpellier, Cedex 4, France.
authors.forename: Gérard
authors.initials: G
authors.lastname: Fabre
keywords: Antiarrhythmic drug; cytochrome P450; dronedarone metabolism; metabolite identification; monoamine oxidase