enalapril and bunazosin

To elucidate the mechanism underlying the sodium retention caused by alpha 1-adrenoceptor blockade in man, a placebo-controlled, randomised, double-blind study has been made of the acute effects of bunazosin an alpha 1-antagonist, on urinary sodium excretion, atrial natriuretic peptide (ANP), arginine vasopressin (AVP), and the renin-aldosterone system in 7 healthy men. A single oral dose of bunazosin 2.0 mg caused a significant reduction (P less than 0.05) in urinary sodium excretion after 0-2 h, 2-4 h, and 4-6 h. The mean values for plasma ANP, AVP, aldosterone, and cortisol concentrations at those times were similar after placebo and bunazosin, and plasma renin activity was significantly increased 2 and 4 h after bunazosin. Pretreatment with oral enalapril 10 mg, an angiotensin converting enzyme inhibitor, did not prevent the bunazosin-induced reduction in urinary sodium excretion. There was a significant positive correlation between the drug-induced changes in blood pressure and urinary sodium excretion. The results suggest that ANP, AVP, and renin-aldosterone may play little role in the sodium retention caused by acute alpha 1-adrenoceptor blockade in man.

Topics: Adrenergic alpha-Antagonists; Adult; Arginine Vasopressin; Atrial Natriuretic Factor; Enalapril; Humans; Male; Premedication; Quinazolines; Renin-Angiotensin System; Sodium

Topics: Adrenergic alpha-Antagonists; Adult; Blood Pressure; Cholinesterase Inhibitors; Drug Synergism; Enalapril; Humans; Quinazolines

We investigated the cerebral blood flow in mild to moderately hypertensive patients with chronic cerebral infarction before and after the administration of bunazosin hydrochloride sustained-release formulation, a selective sympathetic alpha1 receptor blocker.. Eleven mild to moderately hypertensive patients (mean age 65.6 years) with chronic cerebral infarction were studied.. The patients were on enalapril maleate, an angiotensin converting enzyme inhibitor, for one week and then enalapril maleate was switched to bunazosin hydrochloride sustained-release formulation.. The cerebral blood flow study was performed before and 8 weeks after starting the administration of bunazosin hydrochloride sustained-release formulation. Cerebral blood flow was measured using the stable xenon CT method. The picture analysis was performed using AZ-7000. The regional cerebral blood flow was measured by placing the region of interest on the CT images. The regional cerebral blood flows were measured before and 20 minutes after intravenous injection of 17 mg/kg acetazolamide.. The blood flows in the parietal cortex and caudate nucleus 8 weeks after starting the administration of bunazosin hydrochloride sustained-release formulation were significantly greater than those before. The cerebrovascular acetazolamide reactivity in the occipital cortex and caudate nucleus was significantly lower after switching to bunazosin hydrochloride sustained-release formulation than before.. Considering the reports that angiotensin converting enzyme inhibitors show little influence on cerebral blood flow, the present study suggests that bunazosin hydrochloride sustained-release formulation may show a good influence on cerebral blood flow in mild to moderately hypertensive patients with chronic cerebral infarction.

Topics: Acetazolamide; Adrenergic alpha-Antagonists; Aged; Angiotensin-Converting Enzyme Inhibitors; Blood Flow Velocity; Caudate Nucleus; Cerebral Infarction; Cerebrovascular Circulation; Delayed-Action Preparations; Diuretics; Enalapril; Female; Humans; Injections, Intravenous; Male; Occipital Lobe; Parietal Lobe; Quinazolines; Tomography, X-Ray Computed