title: A population pharmacokinetic evaluation of the influence of CYP2D6 genotype on risperidone metabolism in patients with acute episode of schizophrenia.
abstract: The objective of this prospective study was to characterize the metabolism of risperidone to (+)- and (-)-9-hydroxyrisperidone in vivo and to evaluate the influence of CYP2D6 genotype. A population pharmacokinetic modeling approach was used to estimate the interindividual variability of the pharmacokinetic parameters in 50 hospitalized patients with acute episode of schizophrenia. CYP2D6 genotype remarkably influenced the formation clearances of the risperidone metabolites, while creatinine clearance was related to the plasma clearance of 9-hydroxyrisperidone. CYP2D6 genotype was also associated with the average plasma concentration of risperidone active moiety (a sum of all three active compounds). In comparison to the patients with CYP2D6*1/*1 genotype, average steady-state plasma concentration of risperidone active moiety was 3.3- and 1.6-fold higher in poor metabolizers (both alleles nonfunctional; CYP2D6*3 or *4) and intermediate metabolizers (one nonfunctional allele and one allele for diminished enzyme activity; CYP2D6*10 or *41), respectively. Additionally, average plasma concentration of risperidone active moiety was higher in the patients with dystonia (p=0.0066) and parkinsonism (p=0.046). The results of this study imply the potential role of CYP2D6 genotyping in personalizing risperidone therapy in patients with schizophrenia to reduce the incidence of adverse extrapyramidal symptoms.
authors.affiliation: Department of Biopharmaceutics and Pharmacokinetics, Faculty of Pharmacy, University of Ljubljana, Askerceva cesta 7, Ljubljana, Slovenia.
authors.forename: Igor
authors.initials: I
authors.lastname: Locatelli
authors.forename: Matej
authors.initials: M
authors.lastname: Kastelic
authors.forename: Jure
authors.initials: J
authors.lastname: Koprivsek
authors.forename: Blanka
authors.initials: B
authors.lastname: Kores-Plesnicar
authors.forename: Ales
authors.initials: A
authors.lastname: Mrhar
authors.forename: Vita
authors.initials: V
authors.lastname: Dolzan
authors.forename: Iztok
authors.initials: I
authors.lastname: Grabnar
mesh_terms: D000208:Acute Disease; D014150:Antipsychotic Agents / Q000378:metabolism* / Q000493:pharmacokinetics; D019540:Area Under Curve; D001483:Base Sequence; D001499:Bayes Theorem; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics*; D017931:DNA Primers; D005838:Genotype; D006801:Humans; D018967:Risperidone / Q000378:metabolism* / Q000493:pharmacokinetics; D012559:Schizophrenia / Q000378:metabolism*
chemical_list: D014150:Antipsychotic Agents; D017931:DNA Primers; D019389:Cytochrome P-450 CYP2D6; D018967:Risperidone