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Cited by 6Forensic Toxicology and Drug AnalysisPharmaceutical Quality and CounterfeitingOpioid Use Disorder Treatment

Emergence of counterfeit oxycodone tablets containing Nitazenes in France: First national alert and analytical characterization

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Dugues, Paméla, Rabai, Abderrahmane, Chenorhokian, Sevag, Pfau, Gregory, Cherki, Sabrina, Bellouard, Marie, Alvarez, Jean Claude, Larabi, Islam Amine·2025·Toxicologie Analytique et Clinique
DOI 10.1016/j.toxac.2025.07.002
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Abstract

Background Nitazenes, a class of synthetic opioids more potent than fentanyl, have been increasingly detected in the global illicit drug market, particularly within counterfeit medicines, causing intoxication and death. They represent a significant public health concern due to their high toxicity and their invisibility to conventional toxicological screening methods. Methods Five counterfeit oxycodone tablets were collected in Paris by a drug-checking service between February and May 2025. Visual inspection indicated the tablets mimicked authentic oxycodone “M30” formulations. Two tablets were received intact and three in powder form (ground beforehand). Analytical testing was conducted using LC-DAD, GC-MS, LC-MS/MS, and LC-HRMS. Quantification was performed by LC-MS/MS for 340 substances, including 163 new psychoactive substances (NPS). Results No oxycodone was detected in any of the samples; instead, all contained the synthetic opioids metonitazene and protonitazene. Quantification showed that tablets contained between 3.2% and 6.0% metonitazene, with protonitazene present in smaller amounts (less than 0.2%). The estimated metonitazene content in intact tablets ( n = 2) ranged from 3.7 to 4.0 mg, approximately equivalent to 23 mg of fentanyl, far exceeding lethal thresholds. Conclusion These findings confirm the circulation of synthetic opioids in counterfeit tablets sold as oxycodone in Paris and its suburbs. The presence of multiple nitazenes underscores the complexity and risk of the current illicit market. Drug-checking services and toxicological analyses are essential for early detection and public health response. Enhanced surveillance, harm reduction, and regulatory coordination are urgently required to mitigate the growing threat of nitazene-related poisonings worldwide.

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Crossref · 10.1016/j.toxac.2025.07.002

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  • Following international scheduling in 2021, a rapid proliferation of other nitazene analogues has emerged worldwide, with dozens reported in toxicology investigations and seized-drug casework.

    “Following its international scheduling in 2021, a rapid proliferation of other nitazene analogues has emerged worldwide, with dozens of different nitazene analogues now reported in both toxicology investigations and seized-drug casework [6,7,8,9].”

    From Nitazenes: The Emergence of a Potent Synthetic Opioid Threat (2025) · cites this paper as [7]

  • The first nitazene widely identified in the recreational drug market was isotonitazene, in 2019, in Europe, Canada, and the United States.

    “The first nitazene to be widely identified in the recreational drug market was isotonitazene, in 2019, in Europe, Canada, and the United States.”

    From Nitazenes: The Emergence of a Potent Synthetic Opioid Threat (2025) · cites this paper as [7]

  • Polysubstance use, often involving combinations with fentanyl, methamphetamine, amphetamine, or flualprazolam, further complicates clinical management and increases the risk of synergistic respiratory depression.

    “This polysubstance use, often involving combinations with fentanyl, methamphetamine, amphetamine, or flualprazolam, further complicates clinical management and increases the risk of synergistic respiratory depression [7,12,27].”

    From Nitazenes: The Emergence of a Potent Synthetic Opioid Threat (2025) · cites this paper as [7]

  • The rapid and consistent emergence of novel nitazene analogues with slight chemical modifications enables them to circumvent existing drug laws, which are often based on specific substances, creating a regulatory lag.

    “Regulatory evasion: The rapid and consistent emergence of novel nitazene analogues with slight chemical modifications enables them to circumvent existing drug laws, which are often based on specific substances, creating a regulatory lag.”

    From Nitazenes: The Emergence of a Potent Synthetic Opioid Threat (2025) · cites this paper as [7]

  • Nitazene analogues are relatively straightforward to synthesise, do not require controlled precursors, and can be produced in small-scale clandestine laboratories worldwide.

    “Ease of synthesis: Nitazene analogues are relatively straightforward to synthesise, do not require controlled precursors, and can be produced in small-scale clandestine laboratories worldwide.”

    From Nitazenes: The Emergence of a Potent Synthetic Opioid Threat (2025) · cites this paper as [7]

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Authors
Dugues, P., Rabai, A., Chenorhokian, S., Pfau, G., Cherki, S., Bellouard, M., Alvarez, J. C., & Larabi, I. A.
Affiliations
Inserm (FR)
ORCID
Venue
Toxicologie Analytique et Clinique
Publisher
Elsevier BV
Published
2025-12
Volume
37
Issue
4
Pages
529-539
ISSN
  • 0768-598X (ISSN-L)
  • 2352-0078
DOI
10.1016/j.toxac.2025.07.002
OpenAlex
W4412913891
Cited by
6
References
24
Citations by year
2026: 3 · 2025: 3
FWCI
3.08
Type
journal article
Language
fr
Open access
Licence
Locations
Annales de Toxicologie Analytique (publishedVersion, cc-by-nc-nd)
Topics
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Toxicology › Forensic Toxicology and Drug Analysis
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Pharmaceutical Quality and Counterfeiting
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Opioid Use Disorder Treatment
Keywords
nitazenes, synthetic opioids, drug checking, illicit drug markets, new psychoactive substances, opioid toxicity, pharmacovigilance, harm reduction

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