Evaluation of a homogenous enzyme immunoassay for the detection of synthetic cannabinoids in urine

Abstract

Introduction The recent emergence and widespread availability of many new synthetic cannabinoids support the need for an accurate and high-throughput urine screen for these new designer drugs. We evaluated performance of the immunalysis homogeneous enzyme immunoassay (HEIA) to sensitively, selectively, and rapidly identify urinary synthetic cannabinoids. Methods 2443 authentic urine samples were analyzed with the HEIA that targets JWH-018 N-pentanoic acid, and a validated LC-MS/MS method for 29 synthetic cannabinoids and metabolites. Semiquantitative HEIA results were obtained, permitting performance evaluation at and around three cutoffs (5, 10 and 20 μg/L), and diagnostic sensitivity, specificity and efficiency determination. Performance challenges at ±25 and ±50% of each cutoff level, cross-reactivity and interferences also were evaluated. Results Sensitivity, specificity, and efficiency of the immunalysis HEIA K2 Spice kit with the manufacturer's recommended 10 μg/L cutoff were 75.6%, 99.6% and 96.8%, respectively, as compared to the reference LC-MS/MS method with limits of detection of 0.1 -10 μg/L. Performance at 5 μg/L was 92.2%, 98.1% and 97.4%, and for the 20 μg/L cutoff were 62.9%, 99.7% and 95.4%. Semi-quantitative results for in-house prepared standards were obtained from 2.5-30 μg/L, and documented acceptable linearity from 5-25 μg/L, with inter-day imprecision <30% (n = 17). Thirteen of 74 synthetic cannabinoids evaluated were classified as highly cross-reactive (≥50% at 10 μg/L); 4 showed moderate cross-reactivity (10–50% at 10 μg/L), 30 low cross-reactivity (<10% at 500 μg/L), and 27 <1% cross-reactivity at 500 μg/L. There was no interference from 102 investigated compounds. Only a mixture containing 1000 μg/L each of buprenorphine/norbuprenorphine produced a positive result above our proposed cutoff (5 μg/L) but below the manufacturer's recommended cutoff concentration (10 μg/L). Conclusion The Immunalysis HEIA K2 Spice kit required no sample preparation, had a high-throughput, and acceptable sensitivity, specificity and efficiency, offering a viable method for screening synthetic cannabinoids in urine that cross-react with JWH-018 N-pentanoic acid antibodies.

Simultaneous quantification of 37 synthetic cannabinoid metabolites in human urine by liquid chromatography-tandem mass spectrometry

“…However, synthetic cannabinoids cannot be detected by most preliminary immunoassay screening procedures, which contribute to the prevalent use of these drugs. In spite of the recent development of immunoassays that target synthetic cannabinoids, they are still limited due to insufficient specificity and the continuous emergence of newly modified synthetic cannabinoids [13,14]. Thus, some screening methods employing mass spectrometric techniques have been developed for selective and sensitive detection of synthetic cannabinoids and their metabolites in various biological matrices [15][16][17][18][19].…”

Pneumomediastinum: A Complication of Synthetic Cannabinoid K2 Use

“…Liquid chromatography and homogenous enzyme immuno-assay (HEIA) spectrometry have been proposed as diagnostic methods [31,32]. Sensitivity, specificity, and efficiency of HEIA K2 spice kit is based on quantitative cut-off points.…”

“…Based on the trails, the manufacturer's recommended cut-off point was 10 μg/L. The sensitivity, specificity, and efficiency for that cut-off were 75.6%, 99.6% and 96.8%, respectively [31]. Management of SC/K2 intoxication is mainly supportive, aimed at fluid resuscitation, airway protection, management of electrolyte imbalance and minimizing organ damage.…”

Bioanalytical methods for the determination of synthetic cannabinoids and metabolites in biological specimens

“…Moreover, cross-reactivity and false positives can occur, and as such, toxicologists recommend that all positive immunoassay findings must be retested and confirmed by chromatographic analysis. Immunoassay tests have been used for the screening of SCs in oral fluid [101] and their metabolites in urine samples [82,93,[102][103][104]. …”