5. LC-MS/MS Observations on the Metabolic Ratio of Oxycodone to Oxymorphone in Urine Samples from Pain Patients
Tue 12:12 PM - PosterSplash Track 1
David A. Yee
University of California, San Diego
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Advancements in LC-MS/MS allow quantitative urine drug monitoring of oxycodone and its metabolite oxymorphone. This opens possibility monitoring adherence and forming predictive models of effectiveness and toxicity of oxycodone treatment. We found a 28.5% nonadherence rate in pain patients. It was observed that increasing concentrations of oxycodone lead to smaller proportions of oxymorphone suggesting saturation of oxycodone metabolism. Samples with concentrations of oxycodone above 100,000 ng/mL, contained a sub-population of subjects with metabolic ratios roughly 100-fold less than the predictive model. This study shows that it is possible to identify slow metabolizers who may be at risk for adverse events.