Nitazene-related deaths in Norway 2021–2024

Nitazenes are potent synthetic opioids that were never marketed as analgesics, due to the high overdose risk with rapid respiratory arrest and death. This study aims to present the nitazene concentrations and toxicological findings in all nitazene-related deaths registered in Norway during 2021-2024. De-identified data from the LIMS database (Oslo University Hospital) and the Beaker database (St. Olavs Hospital) were extracted for all forensic autopsy cases in Norway with nitazenes detected in blood from January 2021 to October 2024, including nitazene and drug concentrations in peripheral blood and urine, age, gender, location of autopsy, date of death, and sampling date. Analysis of nitazenes was performed using liquid chromatography-mass spectrometry methods. Altogether, 36 nitazene-related deaths were registered in Norway; one death in 2021 (etonitazepyne (N-pyrrolidino etonitazene)), one death in 2022 (protonitazene), 13 deaths in 2023 (metonitazene n = 11, metonitazepyne (N-pyrrolidino metonitazene) n = 1, N-desethyl isotonitazene n = 1), and 21 deaths in 2024 (metonitazene n = 18, protonitazepyne (N-pyrrolidino protonitazene) n = 3). The nitazene-related deaths occurred in all regions of Norway, the majority were males (94.4 %), and median age was 29 years (range 19-56 years). Over 90 % of the cases also had one or more of other psychoactive drugs detected in blood, and 50 % had one or more designer benzodiazepines detected. The median (range) concentrations in post-mortem peripheral blood were 7.3 ng/ml (0.8-114.7 ng/ml) for metonitazene (n = 28) and 3.4 ng/ml (2.0-3.7 ng/ml) for protonitazepyne (n = 3). In summary, since June 2023 the prevalence of nitazene-related deaths escalated in Norway, and the majority were males in their twenties or younger. Our findings indicate that inexperienced drug users need better information about the extreme risk of accidental overdose when using such potent opioids.