Metonitazene is an analgesic compound related to etonitazene,^[2][3] which was first reported in 1957,^[4] and has been shown to have approximately 1000 times the potency of morphine by central routes of administration,^[5] but if used orally it has been shown to have approximately 10 times the potency of morphine.^[6]

Its effects are similar to other opioids such as fentanyl and heroin, including analgesia, euphoria, and sleepiness.^[6][7] Adverse effects include vomiting, and respiratory depression that can potentially be fatal.^[8] Because of high dependency potential and dangerous adverse effects it has never been introduced into pharmacotherapy. It is instead commonly used in the illicit manufacture of counterfeit-OxyContin opioid pills.

In the United States, metonitazene is a Schedule I controlled substance under the Controlled Substances Act.

Metonitazene is not controlled under the 1971 Convention on Psychotropic Substances; however, in many countries possession or intent to sell for human consumption might be prosecuted under several analog acts.

• AH-7921
• Etonitazepyne
• Isotonitazene
• MT-45
• Piperidylthiambutene
• U-47700