A comparison of single doses of bucindolol and oxprenolol in hypertensive patients.

Single doses of bucindolol 50, 100 and 200 mg were compared to placebo and single doses of oxprenolol 40, 80 and 160 mg in seven patients with mild hypertension, in a double-blind randomized study. Both bucindolol and oxprenolol inhibited exercise induced tachycardia. The mean maximum inhibition of exercise heart rate was similar after each dose of both drugs (20%, P less than 0.001). Bucindolol produced a significantly greater reduction in blood pressure than either oxprenolol or placebo. This was most apparent in standing systolic and diastolic and post-exercise systolic blood pressures between 1 and 2 h after dosing and was dose-related. All seven patients experienced adverse effects related to hypotension within the first 2 h after ingestion of bucindolol 200 mg. Plasma concentrations of oxprenolol, bucindolol or 5-hydroxy-bucindolol, sampled 2 h after dosing, could not be related to either the changes in blood pressure or to the occurrence of symptoms. The results emphasise the need for careful dose-finding of new drugs prior to their more widespread evaluation in phase 3 studies.