Evaluation of the DRI oxycodone immunoassay for the detection of oxycodone in urine

We evaluated the performance of the DRI Oxycodone (DRI-Oxy) enzyme immunoassay for the detection of oxycodone and its primary metabolite, oxymorphone, in urine, by testing 1523 consecutive urine specimens collected from pain management patients. All 1523 specimens were tested with the DRI-Oxy assay at a cut-off of 100 ng/mL and then analyzed by gas chromatography-mass spectrometry (GC-MS) for opiates, including oxycodone and oxymorphone. Approximately 29% (435) of the 1523 specimens yielded positive results by the DRI-Oxy assay. Of these 435 specimens, GC-MS confirmed the presence of oxycodone and/or oxymorphone at >100 ng/mL in 433 specimens, an agreement of 99.5%. In addition to oxycodone and/or oxymorphone, 189 of the 433 positive specimens contained other opiates including codeine, hydrocodone, hydromorphone, and morphine. These other opiates were also present in 54% (590/1084) of the oxycodone negative specimens. The DRI-Oxy assay demonstrated no cross-reactivity, yielding negative results, with specimens containing concentrations of codeine, >75,000 ng/mL; hydrocodone, >75,000 ng/mL; hydromorphone, >12,000 ng/mL; and morphine, >163,000 ng/mL. From the presented study, the sensitivity of the DRI-Oxy was 0.991 and the selectivity 0.998. The DRI-Oxy assay provided a highly reliable method for the detection of oxycodone and/or oxymorphone in urine specimens.