title: The impact of CYP2C19 and CYP2D6 genotypes on metabolism of amitriptyline in Japanese psychiatric patients.
abstract: We investigated the effect of the CYP2C19 and CYP2D6 genotypes on the metabolism of amitriptyline (AT) in Japanese psychiatric patients. Steady-state concentrations of AT and its metabolites (nortriptyline [NT], trans-10-hydroxy-nortriptyline [EHNT], cis-10-hydroxy-nortriptyline [ZHNT], trans-10-hydroxy-amitriptyline [EHAT], and cis-10-hydroxy-amitriptyline [ZHAT]) in 50 patients were determined by high-performance liquid chromatography. Significantly higher plasma concentrations of AT corrected for dose and body weight in the subjects with two mutated alleles of CYP2C19 than in those with no mutated alleles of CYP2C19 were observed (no mutated alleles vs. two mutated alleles: 36.0 +/- 18.2 vs. 64.0 +/- 25.2 ng/mL/mg/kg, p = 0.025). A significantly higher AT/NT ratio was seen in the subjects with two mutated alleles of CYP2C19 than in those with no mutated alleles of CYP2C19 (no mutated alleles vs. two mutated alleles: 1.27 +/- 0.59 vs. 3.40 +/- 1.02, p = 0.001). A trend for higher NT/EHNT ratio in the subjects with two mutated alleles of CYP2D6 than in those with no mutated alleles of CYP2D6 was observed (no mutated alleles vs. two mutated alleles: 0.73 +/- 0.39 vs. 1.31 +/- 0.81, p = 0.068). A trend for higher plasma concentrations of total hydroxylated metabolites of AT (EHAT + ZHAT) corrected for dose and body weight in the subjects with two mutated alleles of CYP2C19 than in those with no mutated alleles of CYP2C19 was found (no mutated alleles vs. two mutated alleles: 9.5 +/- 5.8 vs. 17.8 +/- 8.9, p = 0.051). Therefore, the genotype of CYP2C19 is one of the important determinants of the plasma concentrations of AT and the capacity to desmethylate AT. Mother compound AT is shunted via hydroxylation pathways from AT to EHAT and ZHAT in the subjects with homozygotes of mutated alleles of CYP2C19 in order to compensate for the decreased capacity to desmethylate AT.
authors.affiliation: Department of Psychiatry, Shiga University of Medical Science, Shiga, Japan. shimoda@belle.shiga-med.ac.jp
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Shimoda
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Someya
authors.forename: Aya
authors.initials: A
authors.lastname: Yokono
authors.forename: Sachiyo
authors.initials: S
authors.lastname: Morita
authors.forename: Genta
authors.initials: G
authors.lastname: Hirokane
authors.forename: Saburo
authors.initials: S
authors.lastname: Takahashi
authors.forename: Masako
authors.initials: M
authors.lastname: Okawa
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D000639:Amitriptyline / Q000097:blood / Q000378:metabolism* / Q000627:therapeutic use; D000929:Antidepressive Agents, Tricyclic / Q000378:metabolism* / Q000627:therapeutic use; D001189:Aryl Hydrocarbon Hydroxylases; D065731:Cytochrome P-450 CYP2C19; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics* / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics* / Q000378:metabolism; D005260:Female; D005838:Genotype; D006801:Humans; D007564:Japan; D008297:Male; D001523:Mental Disorders / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics* / Q000523:psychology; D008875:Middle Aged; D006899:Mixed Function Oxygenases / Q000235:genetics* / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D012044:Regression Analysis
chemical_list: D000929:Antidepressive Agents, Tricyclic; D000639:Amitriptyline; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D019389:Cytochrome P-450 CYP2D6