beta-Adrenoceptor blocking activity and duration of action of pindolol and propranolol in healthy volunteers.

The beta-adrenoceptor blocking activities of pindolol and propranolol have been investigated in healthy male volunteers. Pindolol was about forty times more potent than propranolol in reducing isoprenaline-induced tachycardia. Pindolol (5 mg) and propranolol (u99 mg) were approximately equiactive in reducing exercise-induced tachycardia, 2 h after oral administration. The duration of action of pindolol is significantly longer than that of propranolol; 24 h after pindolol (kmg), 36+/-5% of the masimum effect were still present, and after propranolol (100 mg) 16+/-4% remained. Despite the long duration of action of pindolol, there was no evidence for cumulation during oral administration of 5 mg t.d.s. for 5 days.