Marianne K Kringen1, Fatemeh Chalabianloo, Jean-Paul Bernard, Jørgen G Bramness, Espen Molden, Gudrun Høiseth. 1. *Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo; †Department of Addiction Medicine, Haukeland University Hospital, Bergen; ‡Norwegian National Advisory Unit on Concurrent Substance Abuse and Mental Health Disorders, Innlandet Hospital Trust, Hamar; §Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, Oslo; ¶Department of Forensic Sciences, Oslo University Hospital, Oslo; and ‖Norwegian Center for Addiction Research, University of Oslo, Oslo, Norway.
Abstract
BACKGROUND: A considerable interindividual variability in methadone pharmacokinetics is seen in patients on methadone maintenance treatment. The aim of this study was to clarify the impact of the reduced function CYP2B6*6 variant allele together with variants in other candidate genes on a steady-state methadone concentration in a naturalistic setting. METHODS: Information of methadone serum concentration, dose, age, sex, and CYP2C9, CYP2C19, and CYP2D6 genotypes were collected from a routine therapeutic drug monitoring database, whereas variant alleles in CYP2B6 and CYP3A5 were retrospectively genotyped. Linear mixed model analyses were used to study the impact of gene variants on methadone serum concentration/dose (C/D) ratios, including age, sex, and time since the last dose intake as covariates. RESULTS: Overall, 155 serum samples from 62 patients were included in this study. The estimated mean methadone C/D ratios was 17.8 nmol·L·mg for homozygous carriers of CYP2B6*6, which was significantly (P < 0.001) higher than noncarriers (9.2 nmol·L·mg). There was no difference in C/D ratios between heterozygous carriers of CYP2B6*6 (9.1 nmol·L·mg) and noncarriers. An increase in mean methadone C/D ratios was also seen for homozygous carriers of CYP3A5*3 and heterozygous carriers of CYP2C9*2 or *3 and CYP2C19*2 or *3. CONCLUSIONS: Patients homozygous for CYP2B6*6 had a >90% higher methadone C/D ratio. Genotyping of CYP2B6 may therefore be of value when assessing dose requirements in methadone maintenance treatment.
BACKGROUND: A considerable interindividual variability in methadone pharmacokinetics is seen in patients on methadone maintenance treatment. The aim of this study was to clarify the impact of the reduced function CYP2B6*6 variant allele together with variants in other candidate genes on a steady-state methadone concentration in a naturalistic setting. METHODS: Information of methadone serum concentration, dose, age, sex, and CYP2C9, CYP2C19, and CYP2D6 genotypes were collected from a routine therapeutic drug monitoring database, whereas variant alleles in CYP2B6 and CYP3A5 were retrospectively genotyped. Linear mixed model analyses were used to study the impact of gene variants on methadone serum concentration/dose (C/D) ratios, including age, sex, and time since the last dose intake as covariates. RESULTS: Overall, 155 serum samples from 62 patients were included in this study. The estimated mean methadone C/D ratios was 17.8 nmol·L·mg for homozygous carriers of CYP2B6*6, which was significantly (P < 0.001) higher than noncarriers (9.2 nmol·L·mg). There was no difference in C/D ratios between heterozygous carriers of CYP2B6*6 (9.1 nmol·L·mg) and noncarriers. An increase in mean methadone C/D ratios was also seen for homozygous carriers of CYP3A5*3 and heterozygous carriers of CYP2C9*2 or *3 and CYP2C19*2 or *3. CONCLUSIONS:Patients homozygous for CYP2B6*6 had a >90% higher methadone C/D ratio. Genotyping of CYP2B6 may therefore be of value when assessing dose requirements in methadone maintenance treatment.
Authors: Senthil Packiasabapathy; Blessed W Aruldhas; Nicole Horn; Brian R Overholser; Sara K Quinney; Janelle S Renschler; Senthilkumar Sadhasivam Journal: Pharmacogenomics Date: 2020-07-24 Impact factor: 2.533
Authors: Blessed W Aruldhas; Sara K Quinney; Brian R Overholser; Michael A Heathman; Andrea R Masters; Reynold C Ly; Hongyu Gao; Senthil Packiasabapathy; Senthilkumar Sadhasivam Journal: CPT Pharmacometrics Syst Pharmacol Date: 2021-08-26
Authors: Immaculate M Langmia; Katja S Just; Sabrina Yamoune; Jürgen Brockmöller; Collen Masimirembwa; Julia C Stingl Journal: Front Genet Date: 2021-07-12 Impact factor: 4.599