What is "isomethadone"

n. A synthetic opioid analgesic and antitussive related to methadone.

Isomethadone ( INN, BAN; Liden), also known as isoamidone, is a synthetic opioid analgesic and antitussive related to methadone that was used formerly as a pharmaceutical drug but is now no longer marketed. Isomethadone was used as both an analgesic and antitussive. It binds to and activates both the μ- and δ-opioid receptors, with the (S)- isomer being the more potent of its two enantiomers. Isomethadone is a Schedule II controlled substance in the United States, with an ACSCN of 9226 and a 2014 aggregate manufacturing quota of 5 grammes. The salts in use are the hydrobromide (free base conversion ratio 0.793), hydrochloride (0.894), and HCl monohydrate (0.850). Isomethadone is also regulated internationally as a Schedule I controlled substance under the United Nations Single Convention on Narcotic Drugs of 1961.