Ethnic and genetic factors in methadone pharmacokinetics: a population pharmacokinetic study.

Article Details

Citation

Bart G, Lenz S, Straka RJ, Brundage RC

Ethnic and genetic factors in methadone pharmacokinetics: a population pharmacokinetic study.

Drug Alcohol Depend. 2014 Dec 1;145:185-93. doi: 10.1016/j.drugalcdep.2014.10.014. Epub 2014 Oct 24.

PubMed ID
25456329 [ View in PubMed
]
Abstract

BACKGROUND: Treatment of opiate use disorders with methadone is complicated by wide interindividual variability in pharmacokinetics. To identify potentially contributing covariates in methadone pharmacokinetics, we used population pharmacokinetic modeling to estimate clearance (CL/F) and volume of distribution (V/F) for each methadone enantiomer in an ethnically diverse methadone maintained population. METHODS: Plasma levels of the opiate-active R-methadone and opiate-inactive S-methadone were measured in 206 methadone maintained subjects approximately two and twenty-three hours after a daily oral dose of rac-methadone. A linear one-compartment population pharmacokinetic model with first-order conditional estimation with interaction (FOCE-I) was used to evaluate methadone CL/F and V/F. The influence of covariates on parameter estimates was evaluated using stepwise covariate modeling. Covariates included ethnicity, gender, weight, BMI, age, methadone dose, and 21 single nucleotide polymorphisms in genes implicated in methadone pharmacokinetics. RESULTS: In the final model, for each enantiomer, Hmong ethnicity reduced CL/F by approximately 30% and the rs2032582 (ABCB1 2677G>T/A) GG genotype was associated with a 20% reduction in CL/F. The presence of the rs3745274 minor allele (CYP2B6 515G>T) reduced CL/F by up to 20% for S-methadone only. A smaller effect of age was noted on CL/F for R-methadone. CONCLUSION: This is the first report showing the influence of the rs2032582 and rs3745274 variants on methadone pharmacokinetics rather than simply dose requirements or plasma levels. Population pharmacokinetics is a valuable method for identifying the influences on methadone pharmacokinetic variability.

DrugBank Data that Cites this Article

Drugs
Pharmaco-genomics
DrugInteracting Gene/EnzymeAllele nameGenotypesDefining change(s)Type(s)DescriptionDetails
MethadoneATP-dependent translocase ABCB1
Gene symbol: ABCB1
UniProt: P08183
---GGpgx reviewThe ABCB1 2677G > T/A GG genotype affects methadone pharmacokinetics and was associated with a 20% reduction in CL/F.Details
MethadoneCytochrome P450 2B6
Gene symbol: CYP2B6
UniProt: P20813
CYP2B6*6Not Availablepgx reviewThe presence of the rs3745274 minor allele (CYP2B6 515G > T) has been found to affect methadone pharmacokinetics. It reduces CL/F by up to 20% for S-methadone only and reduces (R)- and (S)-methadone N-demethylation,Details