Pharmacogenetics of opioid response
A A Somogyi1, J K Coller, D T Barratt
1Discipline of Pharmacology, School of Medical Sciences, Faculty of Health Sciences, University of Adelaide, Adelaide, Australia; Centre for Personalised Cancer Medicine, University of Adelaide, Adelaide, Australia; Department of Clinical Pharmacology, Royal Adelaide Hospital, Adelaide, Australia.
Clinical Pharmacology and Therapeutics
|February 12, 2015
Summary
Genetic variations in opioid metabolism, particularly CYP2D6, impact pain relief and toxicity risk. While tramadol shows clear effects in poor metabolizers, clinical use of opioid genetics remains premature due to complex factors.
Area of Science:
- Pharmacogenomics
- Pain Management
- Opioid Metabolism
Background:
- Opioid analgesics often require metabolic activation to exert their therapeutic effects.
- Genetic variations in drug-metabolizing enzymes, such as Cytochrome P450 2D6 (CYP2D6), can significantly alter drug response.
- Understanding these genetic influences is crucial for optimizing pain management and minimizing adverse events.
Purpose of the Study:
- To review the clinical implications of genetic variations in opioid metabolism, focusing on CYP2D6 and other relevant genes.
- To assess the current state of clinical translation for pharmacogenetic testing in opioid therapy.
- To identify factors hindering the widespread adoption of pharmacogenetics in pain and addiction treatment.
Main Methods:
- Literature review of studies investigating genetic polymorphisms in opioid-metabolizing enzymes and their clinical outcomes.
- Analysis of data on CYP2D6 poor and ultra-rapid metabolizer phenotypes concerning opioid efficacy and toxicity.
- Examination of findings related to ABCB1 and OPRM1 gene variants, particularly in specific populations.
Main Results:
- Poor CYP2D6 metabolizers exhibit reduced formation of active opioid metabolites, leading to minimal pain reduction, reliably demonstrated for tramadol.
- Ultra-rapid CYP2D6 metabolizers face an elevated risk of opioid toxicity, notably with codeine.
- ABCB1 genetic associations lack consistent findings, while OPRM1 variants in Asian populations correlate with increased opioid dosage requirements.
Conclusions:
- Pharmacogenetic variations, especially in CYP2D6, significantly influence opioid efficacy and safety, with differential effects observed in poor and ultra-rapid metabolizers.
- Clinical application of opioid pharmacogenetics is currently premature due to the complex interplay of numerous genetic and non-genetic factors influencing pain and addiction phenotypes.
- Further research is needed to integrate genetic information effectively into personalized pain management strategies.
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