Metabolism and detection of designer benzodiazepines; A systematic review

<b>S</b>ynthesis and illicit use of designer benzodiazepines <b>are</b> growing concern<b>s</b>, with<b>these new</b>psychoactive substances (NPS) posing serious health consequences and new hurdles for toxicologists. <b>Consumption marker i</b>dentification and characterization is paramount in confirming their use. <b>The benzodiazepine core structure is a fusion of benzene and a seven-membered heterocycle with two nitrogen atoms forming the diazepine ring. Minor variations on the core structure produce different classes of benzodiazepines with marked differences in physiological effects.The present review</b> provide<b>s</b> a comprehensive <b>designer benzodiazepines metabolism</b>overview and <b>suggests</b>suitable <b>human consumption</b>biomarkers <b>for toxicology casework</b>. A systematic literature search of PubMed®, Scopus^TM, Web of Science^TM, and <b>Cochranedatabases</b>was conducted independent<b>ly by two coauthors</b>adhering to PRISMA guidelines. <b>Data from 30</b><i>in vitro</i> and <i>in vivo</i> models of designer benzodiazepines metabolism from January 2007 to February 2023 were included. 1,4-benzodiazepines (n = 10), 2,3-benzodiazepines (n = 1), triazolo-benzodiazepines (n = 9), and thieno-triazolo-benzodiazepines (n = 3) study design, sample pretreatment, analytical techniques and major metabolites detected in various matrices <b>are addressed</b>. Metabolites following hydroxylation and phase II glucuronide conjugation were the most prevalent analytes. <i>N</i>-<b>G</b>lucuronidation of parent azole-fused benzodiazepines, andnitro-reduced and <i>N</i>-acetylated metabolites of nitro-containing designer benzodiazepines were also common. From these data, we propose a generic metabolic pathway<b>for designer benzodiazepines</b>. The sporadic illicit market presents challenges in toxicological casework and necessitates comprehensive biomarker investigations, especially in cases with legal implications. There are few<b>metabolism</b>data <b>for</b> many designer benzodiazepines, emphasizing the need for research focusing on closing th<b>e</b>se gaps.