title: Stereoselective inhibition of cytochrome P450 forms by lansoprazole and omeprazole in vitro.
abstract: The stereoselectivity of the inhibitory interaction potential of lansoprazole and omeprazole isomers on six human cytochrome P450 forms was evaluated using human liver microsomes. Lansoprazole enantiomers showed stereoselective inhibition of CYP2C9-catalysed tolbutamide 4-methylhydroxylation, CYP2C19-catalysed S-mephenytoin 4'-hydroxylation, CYP2D6-catalysed dextromethorphan O-demethylation, CYP2E1-catalysed chlorzoxazone 6-hydroxylation and CYP3A4-catalysed midazolam 1-hydroxylation, whereas omeprazole only inhibited CYP2C19 stereoselectively. Of the P450 forms tested, CYP2C19-catalysed S-mephenytoin 4'-hydroxylation was extensively inhibited by both the lansoprazole and omeprazole enantiomers in a competitive and stereoselective manner; the S-enantiomers of both drugs inhibited the hydroxylation more than the R-enantiomers. The estimated K(i) values determined for CYP2C19-catalysed S-mephenytoin 4'-hydroxylation were 0.6, 6.1, 3.4 and 5.7 microM for S-lansoprazole, R-lansoprazole, S-omeprazole and R-omeprazole, respectively. The results indicate that although both lansoprazole and omeprazole are strong inhibitors of CYP2C19, the inhibition of CYP2C19 by lansoprazole is highly stereoselective, whereas the inhibition by omeprazole is less stereoselective. In addition, S-lansoprazole, the most potent CYP2C19 inhibitor, is not a good CYP2C19-selective inhibitor owing to its inhibition of other P450 forms.
authors.affiliation: Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine and Clinical Pharmacology Center, Busan Paik Hospital, Busan, Korea.
authors.forename: K H
authors.initials: KH
authors.lastname: Liu
authors.forename: M J
authors.initials: MJ
authors.lastname: Kim
authors.forename: J H
authors.initials: JH
authors.lastname: Shon
authors.forename: Y S
authors.initials: YS
authors.lastname: Moon
authors.forename: S Y
authors.initials: SY
authors.lastname: Seol
authors.forename: W
authors.initials: W
authors.lastname: Kang
authors.forename: I J
authors.initials: IJ
authors.lastname: Cha
authors.forename: J G
authors.initials: JG
authors.lastname: Shin
mesh_terms: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D002478:Cells, Cultured; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism*; D064748:Dexlansoprazole; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry; D006801:Humans; D064747:Lansoprazole; D008862:Microsomes, Liver / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology*; D009853:Omeprazole / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D013237:Stereoisomerism
chemical_list: D053799:2-Pyridinylmethylsulfinylbenzimidazoles; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D064747:Lansoprazole; D003577:Cytochrome P-450 Enzyme System; D009853:Omeprazole; D064748:Dexlansoprazole