"In the late 1950s, the synthesis of 2-benzylbenzimidazole opioids led to the creation of several compounds now known collectively as nitazenes - although they do not technically meet the current United States Adopted Name (USAN) definition of an “azene.” They were of particular interest because their chemical structures are distinct from the typical morphine-like phenanthrene motif and meperidine analogs like fentanyl. The nitazenes were intended to be developed as analgesics but they were never approved for any therapeutic purpose [1,2] Their potency and street appeal caused them to be compared frequently to fentanyl, although they are structurally unrelated. As the Drug Enforcement Administration (DEA) and the Food and Drug Administration (FDA) have been better able to identify and schedule numerous fentanyl analogs [3], it appears that chemists in clandestine labs have gone back through historical pharmacology research literature for early attempts at developing synthetic opioids [4]. Novel psychoactive substances (NPS), including “novel” synthetic opioid analogs such as the re-emergence of the older nitazene drugs, are considered the driver in the recent upward trends in overdose mortality in the United States [5]. Despite the fact that nitazenes have been identified in the illicit recreational drug supply, few clinicians are aware of them or their implications for emergency medicine."


Pergolizzi J Jr, Raffa R, LeQuang JAK, Breve F, Varrassi G. Old Drugs and New Challenges: A Narrative Review of Nitazenes. Cureus. 2023;15(6):e40736. Published 2023 Jun 21. doi:10.7759/cureus.40736