Flunitazene 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 etonitazene, metonitazene, and isotonitazene. Etonitazene and its analogue synthetic opioids were first synthesized and reported in the literature in the 1950s. Data suggest that this group of
analogues can have potency similar to or greater than fentanyl. However, recent in vitro data suggest that flunitazene is much less potent than fentanyl.
Flunitazene is not explicitly scheduled in the United States; however, etonitazene and isotonitazene are Schedule I substances.