Metonitazene is an analgesic drug related to etonitazene and has been shown to have approximately 100 times the potency of morphine by central routes of administration, but if used orally it has been shown to have approximately 10 times the potency of morphine.
Metonitazene is classified as a novel opioid but is dissimilar from fentanyl and U-series analogues. Novel opioids have been reported to cause psychoactive effects similar to heroin, fentanyl, and other opioids. Novel opioids have also caused adverse events, including deaths, as described in the literature.
Structurally similar compounds to metonitazene include etonitazene, isotonitazene, and clonitazene.
Data suggests that this group of analogues have potency similar to or greater than fentanyl. Etonitazene is reported to be the most potent followed by isotonitazene
and metonitazene. Metonitazene is not explicitly a scheduled substance in the United States; however, etonitazene and clonitazene are Schedule I substances and isotonitazene was recently temporarily placed into Schedule I.
Isotonitazene was previously confirmed by NPS Discovery in November 2019, followed by proliferation in the United States initiating from the midwestern
region. Tentative identification of metonitazene was previously reported in March 2019 out of Canada (Alberta) from testing of drug paraphernalia also containing isotonitazene.