Flunitazene (Fluonitazene) is a benzimidazole derivative with opioid effects, first developed in the 1950s as part of the research that led to better-known compounds such as etonitazene. It is one of the least potent derivatives from this class to have appeared as a designer drug, with only around the same potency as morphine, but nevertheless has been sold since around 2020, and has been linked to numerous drug overdose cases.[1][2][3][4][5][6]
^Lamy FR, Daniulaityte R, Barratt MJ, Lokala U, Sheth A, Carlson RG (August 2021). ""Etazene, safer than heroin and fentanyl": Non-fentanyl novel synthetic opioid listings on one darknet market". Drug and Alcohol Dependence. 225: 108790. doi:10.1016/j.drugalcdep.2021.108790. PMID34091156. S2CID235362241.