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Synthesis, Chemical Characterization, and μ-Opioid Receptor Activity Assessment of the Emerging Group of “Nitazene” 2-Benzylbenzimidazole Synthetic Opioids
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Abstract
Several 2-benzylbenzimidazole opioids (also referred to as “nitazenes”) recently emerged on the illicit market. The most frequently encountered member, isotonitazene, has been identified in multiple fatalities since its appearance in 2019. Although recent scheduling efforts targeted isotonitazene, many other analogues remain unregulated. Being structurally unrelated to fentanyl, little is known about the harm potential of these compounds. In this study, ten nitazenes and four metabolites were synthesized, analytically characterized via four different techniques, and pharmacologically evaluated using two cell-based β-arrestin2/mini-Gi recruitment assays monitoring μ-opioid receptor (MOR) activation. On the basis of absorption spectra and retention times, high-performance liquid chromatography coupled to diode-array detection (HPLC-DAD) allowed differentiation between most analogues. Time-of-flight mass spectrometry (LC-QTOF-MS) identified a fragment with m / z 100.11 for 12/14 compounds, which could serve as a basis for MS-based nitazene screening. MOR activity determination confirmed that nitazenes are generally highly active, with potencies and efficacies of several analogues exceeding that of fentanyl. Particularly relevant is the unexpected very high potency of the N -desethylisotonitazene metabolite, rivaling the potency of etonitazene and exceeding that of isotonitazene itself. Supported by its identification in fatalities, this likely has in vivo consequences. These results improve our understanding of this emerging group of opioids by laying out an analytical framework for their detection, as well as providing important new insights into their MOR activation potential.
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“the presence of a nitazene analogue even at trace amounts, which could be below the cut-off for detection with NTS, may readily give rise to dangerous opioid effects in (unknowing) users.”
From Nitazene test strips: a laboratory evaluation (2024) · cites this paper as [7]
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“we found e.g. etodesnitazene to have a similar in vitro potency and efficacy as fentanyl [7, 13]”
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Metadata
- Authors
- Vandeputte, M. M., Van Uytfanghe, K., Layle, N. K., St. Germaine, D. M., Iula, D. M., & Stove, C. P.
- Affiliations
- Ghent University (BE)
- Laboratory of Toxicology, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent 9000, Belgium
- Cayman Chemical (United States) (US)
- Forensic Chemistry Division, Cayman Chemical Company, Ann Arbor, Michigan 48108, United States
- Corresponding author
- Stove, Christophe P.
- Venue
- ACS Chemical Neuroscience
- Publisher
- American Chemical Society (ACS)
- Published
- 2021-03-24
- Volume
- 12
- Issue
- 7
- Pages
- 1241-1251
- ISSN
- 1948-7193 (ISSN-L)
- OpenAlex
- W3135956040
- Cited by
- 161
- References
- 52
- Citations by year
- 2026: 29 · 2025: 47 · 2024: 31 · 2023: 22 · 2022: 24 · 2021: 8
- FWCI
- 13.85
- Type
- journal article
- Language
- en
- Open access
- green
- doi.org
- Licence
- Locations
- ACS Chemical Neuroscience (publishedVersion)
- PubMed (publishedVersion)
- Ghent University Academic Bibliography (Ghent University) (submittedVersion, other-oa)
- Funders
- Fonds Wetenschappelijk Onderzoek (3S038719)
- Bijzonder Onderzoeksfonds (01J15517)
- Topics
- Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Toxicology › Forensic Toxicology and Drug Analysis
- Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Opioid Use Disorder Treatment
- Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Pharmacology › Alkaloids: synthesis and pharmacology
- Keywords
- nitazenes, isotonitazene, etonitazene, opioid metabolites, illicit drug markets, opioid screening
- MeSH terms
- Analgesics, Opioid, Benzimidazoles, Chromatography, Liquid, Fentanyl
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