title: Effects of various CYP2D6 genotypes on the steady-state plasma concentrations of risperidone and its active metabolite, 9-hydroxyrisperidone, in Japanese patients with schizophrenia.
abstract: The effects of various CYP2D6 genotypes on the steady-state plasma concentrations (Css) of risperidone and its active metabolite, 9-hydroxyrisperidone, were studied in 85 Japanese schizophrenic patients (27 men and 58 women) treated with 6 mg/d risperidone for at least 2 weeks. Plasma concentrations of risperidone and 9-hydroxyrisperidone were measured using liquid chromatography-tandem mass spectrometry. The patients had the following CYP2D6 genotypes: wild-type (wt)/wt (40 patients), CYP2D6*10 (*10)/wt ( 28), CYP2D6*5 (*5)/wt ( 8), *10/*10 ( 5), *5/*10 ( 3), and CYP2D6*4/CYP2D6*14 ( 1), respectively. The Css values of risperidone and 9-hydroxyrisperidone were corrected to the median body weight of 58 kg. The medians (ranges) of the Css of risperidone in the aforementioned genotype groups were 2.2 (0.37-35.7), 6.4 (2.1-26.5), 12.3 (4.7-39.5), 19.4 (13.4-26.4), 64.0 (41.6-68.8), and 91.8 nmol/L. Those values for risperidone-to-9-hydroxyrisperidone ratio were 0.03 (0.01-0.33), 0.06 (0.03-0.19), 0.14 (0.07-0.29), 0.28 (0.25-0.38), 0.48 (0.38-0.58), and 2.35, respectively. The Css of risperidone was significantly (P < 0.05 or P < 0.001) different among the four genotype groups (wt/wt, *10/wt, *5/wt, and *10/*10), except between the *5/wt and *10/*10 groups. Also, the risperidone-to-9-hydroxyrisperidone ratio significantly (P < 0.005 or P < 0.001) differed among these genotype groups. No significant differences were found in the Css of 9-hydroxyrisperidone and the active moiety (the Css of risperidone plus 9-hydroxyrisperidone) among these genotype groups. This study confirms previous findings that the CYP2D6 status affects the Css of risperidone via its strong regulation of 9-hydroxylation of risperidone. However, similar active moiety of risperidone among different genotype groups suggests that the determination of the CYP2D6 genotype has little importance for clinical situations.
authors.affiliation: Department of Neuropsychiatry, Hirosaki University School of Medicine, Hirosaki, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mihara
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kondo
authors.forename: Norio
authors.initials: N
authors.lastname: Yasui-Furukori
authors.forename: Akihito
authors.initials: A
authors.lastname: Suzuki
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ishida
authors.forename: Shingo
authors.initials: S
authors.lastname: Ono
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kubota
authors.forename: Tatsuji
authors.initials: T
authors.lastname: Iga
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Takarada
authors.forename: Ronald
authors.initials: R
authors.lastname: de Vries
authors.forename: Sunao
authors.initials: S
authors.lastname: Kaneko
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007555:Isoxazoles / Q000097:blood*; D007564:Japan; D008297:Male; D008875:Middle Aged; D000068882:Paliperidone Palmitate; D011743:Pyrimidines / Q000097:blood*; D018967:Risperidone / Q000097:blood* / Q000627:therapeutic use; D012559:Schizophrenia / Q000097:blood* / Q000188:drug therapy / Q000235:genetics*
chemical_list: D007555:Isoxazoles; D011743:Pyrimidines; D019389:Cytochrome P-450 CYP2D6; D018967:Risperidone; D000068882:Paliperidone Palmitate