Study of the analgesic effects of galanthamine, a cholinesterase inhibitor.

The effects of galanthamine, an alkaloidal anticholinesterase agent whose chemical structure bears similarity to codeine, was studied in various animal and isolated organ tests. Antinociceptive activity of galanthamine given subcutaneously was detected and compared to physostigmine and morphine in the rat hot plate test. Naloxone partially blocked the effect of galanthamine but not that of physostigmine. Both cholinesterase inhibitors provided analgesia in the mouse acetic acid writhing test. They potentiated the effect of morphine in the rat hot plate test but inhibited the barbiturate anaesthesia potentiation of morphine in the rat. While galanthamine provided analgesia in the intact animal, it failed to produce opiate-like activity in such isolated organs as longitudinal muscle strip of the guinea-pig ileum, mouse vas deferens, and cat nictitating membrane.