Effects of medroxalol on renal function and the renin-angiotensin-aldosterone axis

Ten subjects with hypertension received medroxalol, which blocks both alpha- and beta-adrenergic receptors, has intrinsic sympathomimetic beta 2-agonist properties and is a direct vasodilator. Renal function tests consisting of inulin clearance and p-amino hippuric acid (PAH) clearance, plasma renin activity (PRA) in recumbent and upright postures, and aldosterone excretion rate were performed. After intravenous medroxalol, inulin clearance and PAH clearance rose, renal vascular resistance fell, recumbent PRA was unchanged, and the rise in PRA with upright posture was blunted. After 1 mo on oral medroxalol, blood pressure was controlled while inulin clearance, PAH clearance, and renal vascular resistance were unchanged. The rise in PRA with upright posture remained blunted. Urinary aldosterone excretion was unchanged after 1 mo on medroxalol.