Neuro-muscular depressant action of pindolol in comparison with propranolol and procaine.

The action of beta-adrenergic blockers on neuromuscular function has been reexamined using a recent beta-blocker pindolol (Visken), along with propranolol and procaine, on three isolated skeletal muscle preparations from the same species, frog: hyoglossus muscle stimulated through hypoglossal nerve, rectus abdominis and hyoglossus muscles using acetylcholine as an agonist. The depressant action of pindolol and propranolol was found to be non-competitive. The three test-drugs potentiated the depressant actions of d-tubocurarine and succinylcholine. The results point to a local anaesthetic mode of action of beta-blockers. Pindolol which is 10-40 times more potent than propranolol as a beta-blocker but now shown to be only one-fourth as potent in its neuro-muscular depressant action, may have lesser neuro-muscular side effects than propranolol in patients receiving high doses of propranolol for antihypertensive therapy.