B-330 Homogeneous Enzyme Immunoassay for Hydrocodone

Abstract Background Hydrocodone is a semi-synthetic derivative of codeine and produces opioid-like effects similar to morphine. Hydrocodone (Trade names: Vicodin, Lortab, Hycodan, Vicoprofen) is one of the most frequently prescribed opioids in the U.S. as an antitussive (cough suppressant) and narcotic analgesic agent for the treatment of moderate to severe pain. Its ease of prescription and opioid-like effects has led to widespread drug diversion and abuse. The two commercially available homogeneous immunoassays for the detection of hydrocodone in urine at a cutoff of 300 ng/mL suffer undesirable cross-reactivity to oxycodone and morphine at concentrations below 25 000 ng/mL. ARK Diagnostics has developed the ARK Hydrocodone Assay to detect hydrocodone at a cutoff of 300 ng/mL with no cross-reactivity to oxycodone, morphine, and codeine at concentrations below 100 000 ng/mL. Methods The ARK™ Hydrocodone Assay is a liquid stable homogeneous enzyme immunoassay, consisting of two reagents, with a cutoff of 300 ng/mL and semi-quantitative range up to 800 ng/mL. The performance of this assay was evaluated on the Beckman Coulter AU680 Automated Clinical Chemistry Analyzer. Precision, spiked recovery, specificity, Histogram Overlap Analysis of ±25% controls and the cutoff, and method comparison with LC-MS/MS were evaluated. Results In semi-quantitative mode, total precision ranged from 3.9% to 9.9%CV. Spiked recovery of hydrocodone ranged from 86.2% (720 ng/mL) to 102.9% (240 ng/mL). The active metabolite, hydromorphone, showed an approximate equivalence to the 300 ng/mL hydrocodone cutoff at 299 ng/mL (100.3% cross-reactivity). Histogram overlap analysis showed no overlap between cutoff and control levels. Method correlation with LC-MS/MS using authentic urine samples showed an excellent agreement with a specificity of 100% and sensitivity of 96.9% (98 positives and 128 negatives). Conclusion The ARKTM Hydrocodone Assay measures hydrocodone and its metabolite hydromorphone in human urine with acceptable performance. The assay is sensitive, rapid, and applicable to a wide range of clinical chemistry analyzers.