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In vitro identification of the human cytochrome p450 enzymes involved in the oxidative metabolism of loxapine
Author(s) -
Luo Jiang Ping,
Vashishtha Sarvesh C.,
Hawes Edward M.,
McKay Gordon,
Midha Kamal K.,
Fang Jim
Publication year - 2011
Publication title -
biopharmaceutics and drug disposition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.419
H-Index - 58
eISSN - 1099-081X
pISSN - 0142-2782
DOI - 10.1002/bdd.768
Subject(s) - cyp1a2 , cyp3a4 , cytochrome p450 , microsome , chemistry , cyp2a6 , cyp2d6 , pharmacology , enzyme , cytochrome , flavin containing monooxygenase , biochemistry , in vitro , drug metabolism , monooxygenase , biology
In vitro studies were conducted to identify the hepatic cytochrome P450 (CYP) enzymes responsible for the oxidative metabolism of loxapine to 8‐hydroxyloxapine, 7‐hydroxyloxapine, N ‐desmethylloxapine (amoxapine) and loxapine N ‐oxide. These studies included use of cDNA‐expressed enzymes, correlation analysis with 12 phenotyped human liver microsomal samples, and use of selective inhibitors of cytochrome P450s. The resultant data indicated that loxapine was mainly metabolized by human liver microsomes to (i) 8‐hydroxyloxapine by CYP1A2, (ii) 7‐hydroxyloxapine by CYP2D6, (iii) N ‐desmethyloxapine by CYP3A4 and (iv) loxapine N ‐oxide by CYP3A4. The involvement of flavin‐containing monooxygenase (FMO) in the formation of loxapine N ‐oxide was also observed. Copyright © 2011 John Wiley & Sons, Ltd.