(2S)-2-[17-(Cyclopropylmethyl)-4,5a-epoxy-3-hydroxy-6-methoxy-6a,14-ethano-14a-morphinan-7a-yl]-3,3-dimethylbutan-2-ol hydrochloride
Buprenorphine Hydrochloride is the hydrochloride salt form of buprenorphine, a synthetic phenanthrene with narcotic analgesic activity. Buprenorphine hydrochloride is a partial agonist at the mu-opioid receptor and an antagonist at the kapa-opioid receptor in the central nervous system. However, under the conditions of recommended use it behaves as a classic mu-opioid agonist, mimicking the actions of endogenous peptides at CNS opioid receptors. The agonist action results in a raised pain threshold and increased tolerance to pain.  However, it also causes sedation, physical dependence, and respiratory depressant effects and decreases heart rate and blood pressure.