title: Effect of gamma-oryzanol on cytochrome P450 activities in human liver microsomes.
abstract: The effects of gamma-oryzanol, a drug mainly used for the treatment of hyperlipidaemia, on several cytochrome P450 (CYP) specific reactions in human liver microsomes were investigated to predict drug interactions with gamma-oryzanol in vivo from in vitro data. The following eight CYP catalytic reactions were used in this study: CYP1A1/2-mediated 7-ethoxyresorufin O-deethylation, CYP2A6-mediated coumarin 7-hydroxylation, CYP2B6-mediated 7-benzyloxyresorufin O-debenzylation, CYP2C8/9-mediated tolbutamide methylhydroxylation, CYP2C19-mediated S-mephenytoin 4'-hydroxylation, CYP2D6-mediated bufuralol 1'-hydroxylation, CYP2E1-mediated chlorzoxazone 6-hydroxylation, and CYP3A4-mediated testosterone 6beta-hydroxylation. gamma-Oryzanol had little inhibitory effects on CYP activities, indicating that this compound would not be expected to cause clinically significant interactions with other CYP-metabolized drugs at expected therapeutic concentrations.
authors.affiliation: Tokushima Research Institute, Otsuka Pharmaceutical Co., Ltd., Japan. k_umehara@research.otsuka.co.jp
authors.forename: Ken
authors.initials: K
authors.lastname: Umehara
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Shimokawa
authors.forename: Gohachiro
authors.initials: G
authors.lastname: Miyamoto
mesh_terms: D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology*; D010666:Phenylpropionates / Q000494:pharmacology*
chemical_list: D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D010666:Phenylpropionates; D003577:Cytochrome P-450 Enzyme System; C013172:gamma-oryzanol