First evidence in an oversea French department of the deadly risk of protonitazene use: about 5 post mortem cases (2025)

Protonitazene is a synthetic benzoimidazole opioid of the nitazenes class, developed in the 1950s as an effective analgesic, but never released in the market due to severe side effects and major risk of dependence. The laboratory was involved in the determination of the cause of death for 5 subjects deceased in a French department of the Indian Ocean. The 5 victims were male, aged between 20 and 35 years. The first 2 victims were found dead in their prison cell and the 3 other victims were found dead in a squat. Therefore, we have developed and validated a specific procedure to identify and quantify the drug in post mortem specimens using LC-MS/MS. The procedure involves extraction of 0.5 mL fluid at pH 9.5 with a mixture of organic solvents in presence of 20 ng fentanyl-d5 used as internal standard. Linearity of the method was verified from 0.1 to 20 ng/mL in both whole blood and urine (r² = 0.9983 and 0.9993, respectively). The limit of detection was estimated at 0.05 ng/mL in each matrix. Protonitazene was identified at <LOQ to 0.8 ng/mL, 0.4 to 2.9 ng/mL and 3.0 to 8.0 ng/mL in femoral blood, urine and bile, respectively. Post mortem concentrations were very low, which is consistent with reported high toxicity of protonitazene. As nitazenes represent a growing threat to public health in various parts of the world, this method seems to be a good response to the challenges posed by the identification of this class of substances. [Author's abstract]