Cardiovascular effects of acebutolol and hydrochlorothiazide in essential hypertension.

During a double-blind crossover study of hydrochlorothiazide (HCT) and acebutolol (ACB), 11 patients 45 to 69 years old with essential hypertension underwent studies of forearm blood flow (FBF), arterial resistance (FAR), and venous compliance (FVC) using mercury-in-Silastic plethysmography. Placebo periods of 12 weeks were followed by a variable period of incremental doses of either active drug and a final 12week period at fixed dosage averaging 168 mg/day of HCT (range 100 to 200 mg) or 678 mg/day of ACB (range 400 to 800 mg). Supine diastolic pressures decreased (x ± SEM) from 98 ± 2 to 91 ± 3 mm Hg on HCT (p < 0.05) and from 99 ± 2 to 90 ± 4 mm Hg on ACB (p < 0.05). FAR decreased from 62.4 ± 10.6 to 47.1 ± 6.4 units after HCT (p < 0.05) and from 61.4 ± 10.7 to 53.7 ± 10.0 units after ACB (p < 0.05), whereas FVC increased 24.2% ± 10.9% after HCT (p < 0.05) and 29.1% ± 10.4% after ACB (p < 0.01). Although changes in FAR and FVC were similar after each drug, they were not correlated. Body weight was unaltered by either drug, yet HCT reduced pulse pressure, increased peripheral renin activity, and reduced serum potassium, whereas ACB did not alter these variables. Heart rates increased from 81 to 87 beats/min after HCT but decreased from 82 to 71 beats/min (p < 0.05) after ACB, resulting in a greater decrease in double product (heart rate X systolic pressure) after ACB. Although a similar proportion of patients had diastolic pressures < 90 mm Hg on HCT (6/11) as on ACB (7/11) and peripheral vascular effects were comparable, the central cardiovascular effects of these drugs were quite different. (Hypertension 4: 320-324, 1982)