Conorfone

Conorfone (INN; TR-5109), also known as conorphone and codorphone, as well as conorphone hydrochloride (USAN), is an opioid analgesic that was never marketed. It is an analogue of hydrocodone substituted with an 8-ethyl group and an N-cyclopropylmethyl group. It acts as a mixed agonist-antagonist at the μ-opioid receptor, and is slightly more potent than codeine in analgesic effects but associated with somewhat greater side effects.