Propranolol-hydralazine combination in essential hypertension

The efficacy of a propranolol-hydralazine combination tablet was compared with that of each of its two components in the twice-daily treatment of mild to moderate essential hypertension (diastolic blood pressure: 100 to 125 mmHg). After a three-week, single-blind, placebo period, a 9- to 18-week, single-blind, dose-finding phase with the combination was performed. The daily doses of propranolol/hydralazine were 40 mg/25 mg, 80 mg/25 mg, 80 mg/50 mg, 120 mg/50 mg, 160 mg/50 mg, and 160 mg/100 mg. Of 83 patients, 73 (88%) had decreases in diastolic blood pressure equal to or greater than 10 mmHg. Thirty-eight (46%) patients had a diastolic blood pressure equal to or less than 90 mmHg while taking 80 mg propranolol/50 mg hydralazine or less given BID. Mean systolic and diastolic pressures were reduced by 16.8 mmHg (10.9%) and 17.6 mmHg (16.7%), respectively (P less than 0.001). A ten-week, double-blind, parallel-treatment phase followed in which patients were randomly assigned to the combination tablet or to propranolol or hydralazine. There were significantly larger increases in mean systolic (P less than 0.01) and mean diastolic (P less than 0.03) blood pressure when the components were taken alone than with the combination from the mean of the last three weekly dose-finding visits to the mean of the last four biweekly parallel-treatment visits. The changes in systolic/diastolic blood pressures were: hydralazine (n = 30), 14.43/8.62 mmHg; propranolol (n = 24), 9.87/6.09 mmHg; and the combination (n = 27), 1.47/1.53 mmHg. During the parallel-treatment phase, the proportions of patients with new complaints were: hydralazine, 16/31 (52%); propranolol, 10/25 (40%); and the combination, 11/27 (41%). In the hydralazine group, three patients had cardiovascular events (severe tachycardia, mild palpitations, and skipped heart beats) and two patients had mild anxiety; no such occurrences were noted in the propranolol or combination group. The mean change (increase) in heart rate from the end of dose-finding to the end of the double-blind period was significantly larger for patients taking hydralazine than for patients taking propranolol or the combination. Mean changes for these groups were: hydralazine, 12.4 beats/min; propranolol, 2.9 beats/min; and the combination, 1.8 beats/min (P = 0.0001). This study found the combination of propranolol plus hydralazine to be safe and more effective than either component.