title: Stereoselective metabolism of racemic carvedilol by UGT1A1 and UGT2B7, and effects of mutation of these enzymes on glucuronidation activity.
abstract: Carvedilol, an alpha- and beta-adrenergic blocking drug, is mainly metabolized by CYP2D6, UGT1A1, UGT2B4 and UGT2B7. This drug is administered orally as a racemic mixture of R(+)- and S(-)-enantiomers. It has been reported that CYP2D6 prefers metabolizing S-carvedilol to R-carvedilol stereoselectively. On the other hand, stereoselective metabolism of carvedilol by UGTs is still unclear. Moreover, we have reported that patients with chronic heart failure who had polymorphism in CYP2D6, UGT1A1 and/or UGT2B7 had lower metabolic activity and oral clearance than did patients with no polymorphism. The aim of this study was to clarify stereoselective metabolism of carvedilol by UGT1A1 and UGT2B7 and to determine by using a recombinant enzyme-introduced mutation whether genetic mutation in UGT1A1 and UGT2B7 causes reduction in metabolic activity for carvedilol. A glucuronidation assay using human liver microsomes and recombinant UGT1A1 and UGT2B7 expressed in HeLa cells demonstrated that UGT1A1 prefers metabolizing R-carvedilol to S-carvedilol. On the other hand, UGT2B7 prefers metabolizing S-carvedilol to R-carvedilol. Moreover, G71R mutation of UGT1A1 reduced both affinity and capacity but did not affect stereoselective metabolism. On the other hand, both A71S and H268Y mutations of UGT2B7 reduced capacity but did not affect affinity and, as a result, the efficiency of metabolism was remarkably reduced. However, as in the case of UGT1A1, neither of the mutations affected stereoselective metabolism.
authors.affiliation: Laboratory of Pharmcotherapeutic Information, Department of Biopharmaceutical Sciences and Pharmacy, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12-jo, Nishi-6-chome, Kita-ku, Sapporo, Japan. y-kuma@pharm.hokudai.ac.jp
authors.forename: Yoh
authors.initials: Y
authors.lastname: Takekuma
authors.forename: Toru
authors.initials: T
authors.lastname: Takenaka
authors.forename: Koujiro
authors.initials: K
authors.lastname: Yamazaki
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Ueno
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Sugawara
mesh_terms: D002227:Carbazoles / Q000737:chemistry / Q000378:metabolism*; D000077261:Carvedilol; D014453:Glucuronosyltransferase / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism; D015394:Molecular Structure; D009154:Mutation; D011412:Propanolamines / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013237:Stereoisomerism; D000099148:UGT1A1 Enzyme
chemical_list: D002227:Carbazoles; D000077261:Carvedilol; D014453:Glucuronosyltransferase; D007527:Isoenzymes; D011412:Propanolamines; D011994:Recombinant Proteins; D000099148:UGT1A1 Enzyme; C491474:UGT2B7 protein, human