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In order to find a suitable analgesic for the treatment of postoperative pain in pigs the analgesic effect of buprenorphine, etorphine and pethidine has been compared in 8 domestic pigs. For assessment of the analgesic action one thermal (hot plate) and two mechanical (cannulation of ear vein, needle prick) noxious stimuli have been employed. In a pilot experiment on 2 pigs in which methadone was included the maximal effective doses were estimated for each drug. Methadone was found unsuitable because of unacceptable side effects (respiratory dysfunction, hyperactivity) at effective dose levels. Next buprenorphine 120 μg/kg, etorphine 3 μg/kg and pethidine 20 mg/kg all given intramuscularily were compared in a randomized blind trial with a balanced cross‐over design on 6 pigs. Etorphine proved to have the highest and pethidine the lowest maximal analgesic effect which was especially evident in the needle‐prick test. Buprenorphine proved to have the longest duration of action in all three analgesic tests, in the hot plate test lasting between 7 and 24 hrs. Etorphine had a duration of 3 to 5 hrs whereas the effect of pethidine was short, only lasting about 2 hrs. Etorphine provides a complete analgesia but has a small safety margin for which reason it should be used with caution in the pig. The experimental results indicate that buprenorphine should be the first drug of choice in the treatment of pain after surgical intervention due to its long duration of action and lack of side effects.

1. The antagonistic effect of the p-receptor blocking compounds propranolol, Ph QA 33 and INPEA on ouabain-induced cardiac fibrillations in guinea-pigs was compared with their local anaesthetic and p-receptor blocking properties.2. All three compounds were found capable of increasing the tolerance to ouabain and of reversing ouabain-induced fibrillations, the ED50 being 0.3 mg/kg intravenously, 0.5 mg/kg intravenously, and 1.5 mg/kg intravenously, respectively for propranolol, Ph QA 33 and INPEA. 3. Propranolol and Ph QA 33 were found to be moderate to strong local anaesthetics while INPEA had a considerably weaker though significant effect.4. The order of potency as p-receptor blocking compounds was propranolol > Ph QA 33 > INPEA, the latter compound being less than 1% as active as propranolol. 5. Despite the surprising finding that INPEA was effective against noncatecholamine-induced arrhythmias, the results support the general assumption that the anti-arrhythmic effect of p-receptor blocking compounds is related to their local anaesthetic action rather than to their P-blocking ability.Since the work by Lucchesi (1965) on the dextro and racemic form of pronethalol, several investigations have shown,that the effect of p-adrenergic blocking agents on non-catecholamine-induced arrhythmias is, to a large extent, unrelated to their p-receptor blocking action (Howe & Shanks, 1966). The unspecific anti-arrhythmic effect of P-blocking compounds is now assumed to be due chiefly to their quinidinelike or local anaesthetic action, a property common to most P-blocking agents.

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