Properidine is an opioid, an analgesic, and the isopropyl analog of pethidine.[1] Properidine is under international control and is listed in the United States under the Controlled Substances Act (1970) as a Schedule I substance. It is a narcotic, with an Administrative Controlled Substances Code Number (ACSCN) of 9644 and a 2 gramme annual aggregate manufacturing quota as of 2014. The salt in use is hydrochloride, with a free base conversion ratio of 0.88.[2]