In vitro, in vivo metabolism and quantification of the novel synthetic opioid N-piperidinyl etonitazene (etonitazepipne)
Author:
Berardinelli Diletta12, Taoussi Omayema1, Carlier Jeremy1, Tini Anastasio1, Zaami Simona3, Sundermann Tom4, Busardò Francesco Paolo1, Auwärter Volker2
Affiliation:
1. Department of Biomedical Sciences and Public Health , Marche Polytechnic University , Ancona , Italy 2. Forensic Toxicology , Institute for Legal Medicine, Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg , Freiburg , Germany 3. Department of Anatomical, Histological, Forensic and Orthopaedic Sciences , Sapienza University of Rome , Rome , Italy 4. Institute of Forensic and Traffic Medicine, Heidelberg University Hospital , Heidelberg , Germany
Abstract
Abstract
Objectives
N-piperidinyl etonitazene (etonitazepipne) is a newly synthesized opioid related to the 2-benzylbenzimidazole analog class. Etonitazepipne has been formally notified and placed under intensive monitoring in Europe in January 2022. Nitazenes have high affinity at µ-opioid receptor (MOR). Etonitazepipne, specifically shows a EC50 of 2.49 nM, suggesting about 50 times higher potency combined with higher efficacy compared to morphine. Antinociceptive potency l (‘hot plate test’ with rats) was 192-fold greater than that of morphine.
Methods
Here we report on a post-mortem case involving etonitazepipne and its quantification using a standard addition method (SAM) through liquid chromatography tandem mass spectrometry (LC-MS/MS). In addition, characterization and identification of phase I human metabolites using in vitro assay based on pooled human liver microsomes (pHLM) was performed along with the analysis of authentic urine samples by means of high-performance liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS).
Results
The concentration of etonitazepipne in post-mortem blood and urine was 8.3 and 11 ng/mL, respectively. SAM was validated by assessing the following parameters: intraday and interday repeatability, matrix effect and recovery rate in post-mortem blood. A total of 20 and 14 metabolites were identified after pHLM incubation and urine analysis, respectively. Most pronounced in vitro and in vivo transformations were O-deethylation, hydroxylation, ketone reduction, and combinations thereof.
Conclusions
Considering small traces of the parent drug often found in real cases, the identification of metabolic biomarkers is crucial to identify exposure to this drug. O-deethylated, oxidated metabolites, and combination thereof are proposed as urinary biomarkers along with the parent compound.
Publisher
Walter de Gruyter GmbH
Subject
Biochemistry (medical),Clinical Biochemistry,General Medicine
Reference39 articles.
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