Clinical Pharmacogenetics Implementation Consortium Guideline for CYP2B6 Genotype and Methadone Therapy

Area of Science:

• Pharmacogenomics
• Clinical Pharmacology
• Drug Metabolism

Background:

• Methadone, a racemic mixture, treats opioid use disorder, neonatal abstinence syndrome, and pain.
• R-methadone offers higher analgesia, while S-methadone prolongs the QTc interval.
• CYP2B6 metabolizes methadone enantiomers to inactive EDDP metabolites.

Purpose of the Study:

• To evaluate the clinical significance of CYP2B6 genetic variations on methadone pharmacokinetics, efficacy, and safety.
• To determine if CYP2B6 genotype influences methadone dose requirements or QTc prolongation.

Main Methods:

• Systematic review and expert analysis of published literature on CYP2B6 and methadone.
• Investigation of studies linking CYP2B6 variants to methadone plasma concentrations, clinical effects, and QTc interval changes.

Main Results:

• Most CYP2B6 variants reduce enzyme activity, potentially increasing plasma methadone levels, particularly S-methadone.
• Data do not consistently demonstrate a clinically significant impact of CYP2B6 variability on methadone dose, efficacy, or QTc prolongation.

Conclusions:

• Current evidence does not support altering standard methadone prescribing practices based on CYP2B6 genotype.
• No change in clinical guidelines for methadone dosing or management is recommended based on CYP2B6 genetic status.