Pharmacogenomic testing in patients with chronic pain to support personalized medicine [poster]
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Individual genetic differences influence drug efficacy and adverse events. Pain management involves empiric medication adjustments based on observed clinical outcomes. The CYP2D6 enzyme system metabolizes onefourth of all prescription drugs, including many used for chronic pain (e.g. opiates, selective serotonin reuptake inhibitors, tricylic antidepressants). Approximately 7-14% of people are slow metabolizers, 7% ultra-rapid metabolizers, and 35% carriers of a non-functional CYP2D6 allele, elevating the risk of adverse events when individuals receive multiple drugs metabolized by this system. Translating pharmacogenomic testing into clinical practice requires identification of genetic loci and evaluation of a predictive test in clinical situations. We conducted a pilot cross-sectional study on 78 patients with chronic orofacial pain to determine the prevalence of genetic variation of inherited polymorphisms in CYP2D6. The study sample was part of NIDCR's TMJ Registry and Repository. Patients were evaluated and outcomes analyzed for adverse events and symptom severity. Genotyping was conducted on blood samples using the Sequenom iPLEX® ADME PGx panel of SNPs to identify CYP2D6 variations. The prevalence of CYP2D6 polymorphisms in the study population was similar to the general population. The majority of pain patients (54%) were normal and extensive metabolizers or intermediate metabolizers (22%), 15% rapid metabolizers, and 7% poor metabolizers. Poor metabolizers tended towards high scores on the adverse events checklist and fast metabolizers had high average pain levels. These preliminary results suggest patient care may be improved by genotyping to increase proper drug selection, dose optimization and minimization of adverse drug reactions to improve patient outcomes and safety.