[Benzodiazepines’ reactivity in immunoassay techniques – problems with interpretation]

The progress of civilization and the development of pharmaceuticals industry have caused an increase in psychoactive substances abuse. That is why there are often cases of overdose and poisoning with these substances. Benzodiazepines are among the most commonly used drugs. They are a group of medications producing sedative, anxiolytic, hypnotic, myorelaxant and anticonvulsant effects. Benzodiazepines are a large and diversified group of compounds (over 50 different benzodiazepines are used in clinical treatment), and their metabolites are biologically active. The progress of technology allows the use of more advanced and accurate diagnostic methods. The enzyme multiplied immunoassay technique (EMIT) is a routinely used method in toxicology laboratories, and it is often employed to determine the concentration of benzodiazepines in tested material. This technique is quite easy and quick to perform. However, these advantages have different kinds of consequences, e.g. false-positive results. Therefore, it is important to confirm the results with reference methods. The aim of this study was to evaluate the reactivity of chosen benzodiazepines using the EMITRtoxTMSerum Benzodiazepines Assay.

The precision and accuracy of the results were calculated. Nine benzodiazepines were analyzed (chlordiazepoxide, estazolam, flurazepam, medazepam, nitrazepam, nordazepam, oxazepam, prazepam, and temazepam) using the V-Twin System with EMIT technology from Siemens. Every drug was tested 3 times using different concentrations: 300 ng/mL, 1000 ng/mL, and 2000 ng/mL.

The EMIT test showed the highest precision for the quantitative determination of prazepam, and the lowest precision for the determination of nitrazepam and medazepam, whereas the test’s accuracy was highest for the determination of prazepam, and lowest in the case of nitrazepam.