Unraveling isotonitazene: Insights into chemistry, pharmacology, and analytical techniques in forensic toxicology

Isotonitazene, a highly potent synthetic opioid, has become a major public health issue due to its potency, and it can lead to fatal overdoses, even at low concentrations. A total of 80 people who died from isotonitazene have been reported. Its rapid rise in popularity has presented unique challenges for forensic toxicology laboratories tasked with identifying and quantifying it in biological and non-biological samples due to its low dose, its analogues, lack of reference standard, and matrix effects. As a result, forensic laboratories are continually working to develop and refine analytical techniques. Therefore, a referenced compilation of previously published analytical techniques on isotonitazene for sample preparation, detection, and quantification would be useful.

PubMed and Scopus databases were searched using keywords related to isotonitazene and new synthetic opioids. English-language articles published between November 2019 and April 2025 were included, along with reports from international organizations like the United Nations Office on Drugs and Crime (UNODC), European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), and World Health Organization (WHO).

Isotonitazene is characterized and described in terms of synthesis, physical and chemical properties, available forms, pharmacokinetics, pharmacodynamics, medical use, toxic effects, production, distribution, and trafficking. This article also outlines sample preparation and analytical techniques for identifying and quantifying isotonitazene in both biological and non-biological samples. Lastly, the treatment of synthetic opioid overdoses is discussed.

This review offers forensic scientists, public health authorities, law enforcement, and toxicologists up-to-date data on detecting and quantifying isotonitazene in various biological and non-biological matrices.