Butonitazene is classified as a novel opioid of the benzimidazole sub-class and is structurally dissimilar from fentanyl. Novel opioids have been reported to cause psychoactive effects similar to heroin, fentanyl, and other opioids. Novel opioids have also caused adverse events, including death, as described in the literature. Structurally similar compounds include isotonitazene, etonitazene, and metonitazene. These synthetic opioids were first synthesized and reported in the literature in the 1950s.1 Data suggest that this group of analogues can have potency similar to or greater than fentanyl.2 Etonitazene is reported to be the most potent followed by isotonitazene and metonitazene. Butonitazene is not explicitly scheduled in the United States; however, isotonitazene and etonitazene are Schedule I substances.
