title: MDR1 gene polymorphisms and response to acute risperidone treatment.
abstract: Polymorphic multidrug resistant protein 1 (MDR1) transports drugs against a concentration gradient across the blood-brain barrier and reduces their accumulation in the brain. MDR1 may therefore influence antipsychotic brain availability contributing to inter-individual differences in treatment response and adverse effects, regardless of plasma concentrations. In the present study we investigated the influence of two common MDR1 polymorphisms on the improvement of psychopathological symptoms and occurrence of extrapyramidal side effects (EPS) in Slovenian schizophrenia patients acutely treated with risperidone. A total of 59 clinically well defined patients with first episode schizophrenia spectrum disorders or after tapering their maintenance treatment were genotyped for MDR1 C3435T and G2677T/A. Steady-state plasma concentrations of risperidone active moiety (sum of risperidone and the 9-hydroxyrisperidone) were determined. G2677T/A and C3435T genotypes were not associated to psychopathological symptoms, efficacy of treatment and risk for parkinsonism. Marginal associations with akathisia (p=0.039 and p=0.042, respectively) and dystonia (p=0.013 and p=0.034, respectively) were observed for both G2677T/A and C3435T genotypes. However, higher AIMS and BARS scores were observed only in heterozygous carriers of G2677T/A and C3435T polymorphisms and there was no tendency of gene-dose effect. The present study does not suggest a major influence of MDR1 G2677T/A and C3435T polymorphisms on treatment response during short-term risperidone therapy in patients with schizophrenia or schizoaffective disorder.
authors.affiliation: Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia. matej.kastelic@mf.uni-lj.si
authors.forename: Matej
authors.initials: M
authors.lastname: Kastelic
authors.forename: Jure
authors.initials: J
authors.lastname: Koprivsek
authors.forename: Blanka Kores
authors.initials: BK
authors.lastname: Plesnicar
authors.forename: Alessandro
authors.initials: A
authors.lastname: Serretti
authors.forename: Laura
authors.initials: L
authors.lastname: Mandelli
authors.forename: Igor
authors.initials: I
authors.lastname: Locatelli
authors.forename: Iztok
authors.initials: I
authors.lastname: Grabnar
authors.forename: Vita
authors.initials: V
authors.lastname: Dolzan
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics*; D000328:Adult; D000704:Analysis of Variance; D014150:Antipsychotic Agents / Q000097:blood / Q000627:therapeutic use*; D005260:Female; D056726:Genetic Association Studies; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009069:Movement Disorders / Q000209:etiology; D011110:Polymorphism, Genetic / Q000235:genetics*; D011618:Psychotic Disorders / Q000188:drug therapy / Q000235:genetics; D018967:Risperidone / Q000097:blood / Q000627:therapeutic use*; D012559:Schizophrenia / Q000097:blood / Q000150:complications / Q000188:drug therapy* / Q000235:genetics*; D012565:Schizophrenic Psychology; D017524:Slovenia; D018709:Statistics, Nonparametric; D055815:Young Adult
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D014150:Antipsychotic Agents; D018967:Risperidone