Abstract
Pharmacological properties of buprenorphine were studied in comparison with those of morphine and pentazocine. Buprenorphine was more potent than morphine and pentazocine in analgesic tests, using chemical, thermal, pressure, and electrical stimulation as the nociceptive stimuli. Buprenorphine exhibited analgesic activity in the D'Amour-Smith's test at high stimulus intensity and in the Haffner's test, while pentazocine exhibited little or no analgesic action in these tests. Buprenorphine showed a bell-shaped dose-response curve in the mouse D'Amour-Smith's test at high stimulus intensity. Analgesic action of buprenorphine was antagonized by naloxone administered before buprenorphine, but not antagonized by naloxone administered after buprenorphine. Duration of the analgesic action of buprenorphine was longer than those of morphine and pentazocine. Buprenorphine decreased the amplitudes of evoked potentials which were recorded from the nucleus ventralis posteromedialis, nucleus centralis lateralis, and periaquaductal central gray. As a naloxone antagonist, Buprenorphine was equivalent or less potent than naloxone and more potent than pentazocine. Tolerance developed to the analgesic activity of buprenorphine, but development of tolerance to buprenorphine was less than that of tolerance to morphine. It was concluded that buprenorphine may be a useful analgesic drug because of its high intrinsic activity and long duration of action.
