Abstract: An analgesic composition in parenteral unit dosage form or in a unit dosage form suitable for delivery via the mucosa comprising an amount of buprenorphine which is less than the clinical dose required to achieve pain relief and an amount of naloxone such that the ratio by weight of buprenorphine to naloxone is in the range of from 12.5:1 to 27.5:1, or an amount of naltrexone or nalmefene such that the ratio by weight of buprenorphine to naltrexone or nalmefene is in the range of from 12.5:1 to 22.5:1. The analgesic action of the buprenorphine is potentiated by the low dose of naloxone, naltrexone or nalmefene.

Abstract: An analgesic composition in parenteral unit dosage form or in a unit dosage form suitable for delivery via the mucosa comprising an amount of buprenorphine which is less than the clinical dose required to achieve pain relief and an amount of naloxone such that the ratio by weight of buprenorphine to naloxone is in the range of from 12.5:1 to 27.5:1, or an amount of naltrexone or nalmefene such that the ratio by weight of buprenorphine to naltrexone or nalmefene is in the range of from 12.5:1 to 22.5:1. The analgesic action of the buprenorphine is potentiated by the low dose of naloxone, naltrexone or nalmefene.

Abstract: An analgesic composition in parenteral unit dosage form or in a unit dosage form suitable for delivery via the mucosa comprising an amount of buprenorphine which is less than the clinical dose required to achieve pain relief and an amount of naloxone such that the ratio by weight of buprenorphine to naloxone is in the range of from 12.5:1 to 27.5:1, or an amount of naltrexone or nalmefene such that the ratio by weight of buprenorphine to naltrexone or nalmefene is in the range of from 12.5:1 to 22.5:1. The analgesic action of the buprenorphine is potentiated by the low dose of naloxone, naltrexone or nalmefene.

Abstract: 2-[2-(1,4-Benzodioxanyl)]-2-imidazoline or a non-toxic salt thereof, substantially free of 2-[2-(2-methyl-1,3-benzodioxyl)]- 2-imidazoline or a non-toxic salt thereof.2-[2-(1,4-Benzodioxanyl)]-2-imidazoline or a non-toxic salt thereof characterised in that the nuclear magnetic resonance spectrum of the compound in a protonated form exhibits multiplets in the region of .tau.4.4 and .tau.5.4.Process for the preparation of 2-[2-(1,4-benzodioxanyl)]-2-imidazoline, pharmaceutical compositions thereof or of its salts, and their use as presynaptic .alpha..sub.2 -adrenoreceptor antagonists.