(2S)-2-[17-(Cyclopropylmethyl)-4,5a-epoxy-3-hydroxy-6-methoxy-6a,14-ethano-14a-morphinan-7a-yl]-3,3-dimethylbutan-2-ol hydrochloride
A derivative of the opioid alkaloid THEBAINE that is a more potent and longer lasting analgesic than MORPHINE. It appears to act as a partial agonist at mu and kappa opioid receptors and as an antagonist at delta receptors. The lack of delta-agonist activity has been suggested to account for the observation that buprenorphine tolerance may not develop with chronic use.