Reactivity of Commercial Benzodiazepine Immunoassays to Phenazepam

Abstract

Phenazepam is a long acting benzodiazepine that is not controlled in Canada, the United States or many European countries. The abuse of phenazepam has gained recent attention due to the number of hospitalizations and fatalities resulting from overdose. The compound is relatively potent with recommended doses of 0.5 -1.0 mg, or 1/10th the recommended dose of diazepam, and is easy to obtain locally or from international suppliers via the internet. Increased risk of phenazepam overdose is attributed to its potency and the forms in which it is supplied. Individuals without scales or balances are prone to estimate dose amounts of powder visually, which can result in significant errors. The detection of phenazepam has been described using various methods including GC, GC/MS and LC/MS, but no data regarding the sensitivity of commercially available immunoassays exist. In this study, phenazepam-spiked urine samples were analyzed using five commercial instruments and two point of care devices. The concentrations of phenazepam required for detection ranged from 140-462 ng/mL, which is comparable to those of other benzodiazepines. Laboratorians and clinicians should be confident that phenazepam will be detected via most commercial drugs of abuse screens in patients after significant ingestion.

Detectability of designer benzodiazepines in CEDIA, EMIT II Plus, HEIA, and KIMS II immunochemical screening assays

“…The cross-reactivity results obtained for phenazepam agreed very well with previous findings for both the EMIT II Plus (133% vs. 142%) and the KIMS II (82% vs. 83%) assays. [12] In contrast, recent information from the manufacturer of CEDIA stated a cross-reactivity of only 57% for phenazepam, [17] which is not in agreement with our result of 139%. For flubromazepam, the cross-reactivity value in the KIMS II assay in the present study on urine was somewhat higher than that reported previously with serum matrix (111% vs. 71%).…”

“…[9] Knowledge about the detectability of designer benzodiazepines in commercial benzodiazepine immunoassays is limited. [12] Flubromazepam was found to show 70% cross-reactivity in FPIA and KIMS. [10] In CEDIA, etizolam showed 237% cross-reactivity.…”

“…[11] Phenazepam was reported to be detectable in the EMIT II Plus (Siemens Healthcare Diagnostics, Deerfield, IL, USA) and KIMS II (Roche Diagnostics, Mannheim, Germany) assays with crossreactivity figures of 142% and 83%, respectively. [12] Flubromazepam was found to show 70% cross-reactivity in FPIA and KIMS. [13] Pyrazolam has been studied using FPIA and CEDIA, and, although no cross-reactivity figures were given, the tests were reported not to detect pyrazolam through urinary analysis after a controlled drug intake.…”

Designer Benzodiazepines: A Review of Toxicology and Public Health Risks

“…Furthermore, the newest DBDZ may have high cross-reactivity with common BZD immunoassays, which often do not distinguish between designer and prescribed BZD. Metabolism to licensed BZD, the sale of metabolites of prescribed BZD and the unavailability of confirmatory testing in health care centers pose the risk of an incorrect interpretation of analytical findings [5,127,[155][156][157]. The roles DBZD play in deaths remains poorly understood, and how different pathologists and toxicologists attribute and interpret cause of death is largely unknown.…”

Analytical Methods used for the detection and quantification of benzodiazepines

“…e enzyme-linked immunosorbent assay (ELISA) technique is an immunoenzymatic detection and quantification technique that makes possible to visualize an antigenantibody reaction by means of a color reaction produced by the action on a substrate of an enzyme previously fixed to the antibody. ELISA has been used in many studies to detect BZDs in different biological specimens [24,48,[57][58][59]. ere are several different ELISA methods, namely, the competitive and the noncompetitive ELISA.…”