Etazene induces developmental toxicity in vivo Danio rerio and in silico studies of new synthetic opioid derivative

Abstract

Synthetic opioids are gaining more and more popularity among recreational users as well as regular abusers. One of such novel psychoactive substance, is etazene, which is the most popular opioid drug in the darknet market nowadays. Due to limited information available concerning its activity, we aimed to characterize its developmental toxicity, including cardiotoxicity with the use of in vivo Danio rerio and in silico tools. Moreover, we aimed, for the first time, to characterize the metabolite of etazene, which could become a potential marker of its use for future forensic analysis. The results of our study proved severe dose-dependent developmental toxicity of etazene (applied concentrations 10–300 µM), including an increase in mortality, developmental malformations, and serious cardiotoxic effects, as compared with well-known and used opioid—morphine (applied concentrations 1–50 mM). In silico findings indicate the high toxic potential of etazene which may lead to drug-drug interactions and accumulation of substances. Furthermore, phase I metabolite of etazene resulting from N-dealkylation reaction was identified, and therefore it should be considered as a target for toxicological screening. Nonetheless, the exact mechanism of observed effects in response to etazene should be further examined.

Identification of etazene (etodesnitazene) metabolites in human urine by LC‐HRMS

“…In a recent report on N-piperidinyl etonitazene, it was already suggested that some metabolites would undergo glucuronide conjugation, but no actual conjugates were found. 14 The present findings are comparable with results obtained in a recent etazene metabolism study performed in zebrafish 6 and rats. 21 As metabolism of drugs may differ for zebrafish/rats and humans due to species differences in, for example, expression of metabolic enzymes, it is important to confirm this in human samples.…”

“…However, two less abundant N-oxide metabolites were not detected in the human urine and conversely no phase II metabolites were found in the rat samples. 21 In the zebrafish, only the N-dealkylated metabolite M2 was detected, 6 which in the human urine sample was only present in a small amount. Next to the species difference, time between drug intake and sampling and differences in used analytical techniques should also be considered to explain these (small) discrepancies.…”

“…5 Furthermore, etazene was also found to induce severe dose-dependent toxicity in Danio rerio larvae, including increase in mortality, developmental malformations, and serious cardiotoxicity. 6 Since 2019, an increasing trend in the quantity of seized benzimidazoles has been noticed in Europe. In 2020, 16 seizures (out of a total of 594 opioid seizures) of etazene were reported to the European Monitoring Centre for Drugs and Drugs Addiction (EMCDDA), and etazene was the second most seized nitazene opioid after isotonitazene with 44 seizures.…”

“…Etonitazene and N ‐pyrrolidino etonitazene are considered to be the most potent nitazene analogs so far 5 . Furthermore, etazene was also found to induce severe dose‐dependent toxicity in Danio rerio larvae, including increase in mortality, developmental malformations, and serious cardiotoxicity 6 …”