Fatal polysubstance intoxications involving inhalation of nitazene analogues: identification of fluetonitazepyne and 5-methyl etodesnitazene
Authors:
Open Access
- 10 November 2026
- journal article
- Published by Springer Nature in International journal of legal medicine
Abstract
The illicit opioid market has undergone notable diversification, with 2-benzylbenzimidazoles (nitazenes) representing an increasingly prevalent class of non-fentanyl synthetic opioids. These compounds challenge forensic toxicology through marked µ-opioid receptor potency and rapid structural evolution, often undetected by routine immunoassay screening. We report two fatal polysubstance intoxications involving inhalation of nitazene analogues via vaping devices, identified in biological matrices. GC-MS-based identification was corroborated by untargeted LC-HRMS screening with in silico data mining and confirmed against certified reference standards. Case 1 involved a 40-year-old male found deceased after an estimated 2–3 days without contact. Fluetonitazepyne was quantified at 0.58 ng/mL in peripheral blood alongside ethanol (0.55 g/kg), supra-therapeutic citalopram (340 ng/mL), sub-therapeutic lithium, and cannabinoid metabolites, concordant with a recovered vaping vial containing the same nitazene. Death could not be established with certainty; based on toxicological findings, it was most likely acute fluetonitazepyne intoxication in the presence of central nervous system (CNS) depressants. Case 2 concerned a 22-year-old male with a witnessed cardiorespiratory arrest following inhalation from a vaping device confirmed to contain 5-methyl etodesnitazene. Despite bystander cardiopulmonary resuscitation (CPR), naloxone administration (1.6 mg), and intensive care, he died from acute anoxic encephalopathy approximately 24 h later. Ante mortem peripheral blood confirmed 5-methyl etodesnitazene at 3.3 ng/mL alongside barbital at toxic concentrations (39 mg/L). Concurrent CNS depressant exposure potentiated fatal respiratory depression, more clearly established in Case 2. These cases document the lethal potential of emerging nitazene analogues and the value of untargeted HRMS-based screening in the absence of certified reference standards.Keywords
Funding Information
- University of Lausanne
This publication has 24 references indexed in Scilit:
- 5-Methyl etodesnitazene human metabolism: LC-ESI±-HRMS/MS analysis (mono- and di-protonation) of human hepatocyte incubations and positive biospecimensAnalytical and Bioanalytical Chemistry, 2026
- Clinical Experiences With the Nitazene Class of Synthetic Opioids: A Cohort StudyAnnals of Emergency Medicine, 2025
- Post‐Mortem Identification and Toxicological Findings of Fluetonitazepyne and IsotonitazepyneDrug Testing and Analysis, 2025
- The emergence of nitazenes: a new chapter in the synthetic opioid crisisArchives of Toxicology, 2025
- In vitro structure–activity relationships and forensic case series of emerging 2-benzylbenzimidazole ‘nitazene’ opioidsArchives of Toxicology, 2024
- Pharmacological evaluation and forensic case series of N-pyrrolidino etonitazene (etonitazepyne), a newly emerging 2-benzylbenzimidazole ‘nitazene’ synthetic opioidArchives of Toxicology, 2022
- The Physiology and Maintenance of Respiration: A Narrative ReviewPain and Therapy, 2020
- Liquid chromatography-high resolution mass spectrometry for broad-spectrum drug screening of dried blood spot as microsampling procedureAnalytica Chimica Acta, 2019
- Drug concentrations in post‐mortem femoral blood compared with therapeutic concentrations in plasmaDrug Testing and Analysis, 2013
- Interpreting results of ethanol analysis in postmortem specimens: A review of the literatureForensic Science International, 2007