Quantification Of Oxycodone And Its Major Metabolites In Human Plasma By HPLC/MS/MS
By Mary E. Leonard, Vance Cooper, and Lori Payne
BASi has developed a sensitive, specific and robust method for detecting and quantifying oxycodone and its two major metabolites, noroxycodone and oxymorphone, in human plasma. The assay is performed using LC-MS/MS to quantify these analytes along with three isotopically-substituted internal standards, d oxycodone, d oxymorphone and d noroxycodone.
This assay addresses an important aspect of oxycodone metabolism. Cytochrome P450 isoforms CYP3A and CYP2D6 catalyze oxidation of oxycodone to noroxycodone and oxymorphone, respectively . Oxymorphone itself is a potent analgesic and is thus clinically relevant. It is up to ten times more potent per dose than orally administered morphine. However, the concentration of circulating oxymorphone following oxycodone administration is much lower (2 to 12-fold) than that of noroxycodone. This is especially true among poor metabolizers of oxycodone. Simultaneous quantification of oxymorphone, oxycodone and noroxycodone poses an analytical challenge . The range of the BASi method is 0.1-100 ng/mL for oxycodone and oxymorphone, and 0.5-100 ng/mL for noroxycodone. This method has been validated according to FDA regulations and has been used successfully to measure oxycodone and metabolite concentrations in clinical samples.