Affinity and efficacy studies of buprenorphine analogues at opioid receptors

Buprenorphine is a widely used analgesic. Its in vivo properties are partial agonism at μ-receptors and antagonism at κ-receptors. For the investigation of the role of the tertiary alcohol function in the pharmacology of buprenorphine, a series of ring constrained analogues of buprenorphine, in which the tertiary hydroxyl substituent on C19 is fixed in different positions either above (BU46 and BU95) or below (BU47, BU96, BU48 and BU61) the plane of the ring, have been studied in several biological test systems, include binding assays, isolated tissue bioassays and intracellular assays. [Continues.]