Hemodynamic effects of oxprenolol and propranolol in hypertension

Abstract

Oxprenolol is a β-adrenergic blocker with intrinsic sympathomimetic activity. Such drugs are not currently available in the United States, although they have the advantage of less negative inotropic effect than the available propranolol. In 18 patients with mild essential hypertension, oxprenolol (9 patients) or propranolol (9 patients) was added to thiazide in random double-blind fashion and continued for 7 wk during which supine heart rate, blood pressure, and noninvasively measured cardiac output (by CO2 rebreathing) were determined weekly. With thiazide dosage constant throughout, maximal dose titration to 386.6 ± 52.1 (SEM) mg/day of oxprenolol and 360.0 ± 45.4 mg /day of propranolol was achieved over the first 5 wk. Blood pressure fell with both (141.8 ± 4.8/96.0 ± 2.3 to 128.0 ± 5.1/87.2 ± 1.1 mm Hg on oxprenolol, p < 0.01; 150.8 ± 5.5/98.0 ± 1.7 to 129.9 ± 5.5/86.8 ± 3.4 mm Hg on propranolol, p < 0.01). Cardiac output fell from 6.85 ± 0.63 to 5.77 ± 0.45 1/min (p < 0.01) on oxprenolol, and from 6.79 ± 0.61 to 5.37 ± 0.37 1/min (p < 0.02) on propranolol. Oxprenolol reduced heart rate, from 76.4 ± 2.0 to 65.6 ± 2.1 beats/min (p < 0.001) and it fell from 82.0 ± 3.8 to 65.3 ± 3.7 beats/min (p < 0.001) with propranolol; the fall in heart rate was less but not significantly so for oxprenolol (-14.2 ± 1.8% and -19.8 ± 2.8%, p < 0.1). Thus oxprenolol is equivalent to propranolol in antihypertensive action; minor hemodynannic differences between the two drugs might reflect intrinsic sympathomimetic activity of oxprenolol. Oxprenolol should be considered as all alternative to propranolol. © 1979.