Personalized pain management: The use of pharmacogenomics in pain treatment strategies.

Pain is commonly experienced among Canadians but can be difficult to treat due to complex mechanisms. Several medications used for analgesia (e.g., acetaminophen, NSAIDs, opioids, antidepressants, anticonvulsants), can have variable responses, limiting their safety and effectiveness. Pharmacogenomics studies have uncovered genetic variation found within drug processing (i.e., pharmacokinetic) and response (i.e., pharmacodynamic) pathways that are linked to the development of ineffectiveness and/or adverse effects to analgesics. As a result, several gene-drug associations with strong evidence have been incorporated into clinical practice guidelines. For example, individuals are currently recommended to undergo genetic testing for variation within CYP2C9 (adverse effects to some NSAIDs and anticonvulsants), CYP2D6 (ineffectiveness/adverse effects to some opioids, antidepressants, and anticonvulsants), CYP2C19 (ineffectiveness/adverse effects to some antidepressants), CYP2B6 (adverse effects to some antidepressants), and HLA-A and HLA-B (adverse effects to some anticonvulsants) so that modifications can be made to reduce the likelihood of treatment ineffectiveness/adverse effects. As there is limited evidence for treatment recommendations for all analgesics, and in children and minority ancestral groups, further pharmacogenomics studies are needed to identify additional genetic variation that contributes to undesirable outcomes. Ultimately, pharmacogenomics is helping to develop personalized pain management strategies to improve pain treatment outcomes for all patients.