Cardiovascular consequences of primary antihypertensive therapy with prazosin hydrochloride.

Ten patients with essential hypertension who had no end-organ damage were treated with prazosin, starting with a dose of 1 mg/day. The dose was titrated to a maximal tolerated dose not exceeding 20 mg/day in divided doses or until diastolic blood pressure decreased to 90 mm Hg or lower. Among this study population a statistically significant decrease in blood pressures was achieved in the supine, sitting and standing positions. Baseline studies were repeated after 8 weeks of continuous therapy. There was no significant change in peripheral plasma renin activity, serum aldosterone or urinary sodium excretion. Plasma volume increased significantly and the patient weight increased proportionately. Cardiac ejection fraction at rest did not change significantly after prazosin therapy. Exercise ejection fraction also was not changed significantly from baseline during therapy, and the exercise-induced increase in blood pressure was significantly blunted. No adverse effects of prazosin on cardiac function were detected in this short-term study.