Wiktionary
metethoheptazine
n. (context pharmaceutical drug English) A particular narcotic painkiller.
Wikipedia
Metethoheptazine
Metethoheptazine (WY-535) is an opioid analgesic from the phenazepine family. It was invented in the 1960s.
Metethoheptazine produces similar effects to other opioids, including analgesia, sedation, dizziness and nausea.
Metethoheptazine is not listed as a controlled substance under the Controlled Substances Act 1970 in the United States. The Canadian Controlled Drugs and Substances Act specifically excludes the phenazepine opioids from control.