[Effect of the alpha 1-receptor blocker prazosin and the beta 1-receptor blocker acebutolol and their combination on blood pressure and pressure rate product. Ergometric studies of hypertensive patients]

Abstract

The cardiovascular risk of hypertension depends not only on blood pressure under resting conditions, but particularly on blood pressure increases induced by daily physical and emotional activity. Therefore, the ability of the beta 1-receptor antagonist acebutolol (400 mg/day) and of the alpha 1-receptor antagonist prazosin (4 mg/day) to reduce exercise-induced increases in blood pressure and pressure-rate product during and after standardized ergometric work (50-100 W) was compared in an intrapatient study including 20 outpatients with arterial hypertension (WHO stage 1-2) aged 29-55 years. Both drugs resulted in a significant reduction of systolic (p less than 0.01) and diastolic (p less than 0.001) blood pressure at rest. However, systolic blood pressure (p less than 0.001) and pressure-rate product (p less than 0.001) during exercise were only significantly reduced by acebutolol. The strongest blood pressure lowering effect under all conditions could be achieved by the combination of prazosin and acebutolol. From these findings it is concluded that: (1) beta-adrenoreceptor-blocking agents are the drugs of first choice in the baseline therapy of mild to moderate arterial hypertension, and (2) prazosin potentiates the antihypertensive effect of beta-blocking agents. This therapeutic regimen is recommended especially for hypertensives with ischemic heart disease, because prazosin fails to reduce pressure-rate product as a measure of myocardial O2-consumption.