Antihypertensive and vasodilating effects of acute medroxalol, a new beta-blocker with beta-2-adrenergic receptor stimulation.

Abstract

The effects of medroxalol, a new beta-blocking drug, were simultaneously studied on the brachial artery, the arterioles and the veins of the forearm in 15 patients with mild to moderate essential hypertension after administration of a single oral dose of 200 mg, by means of pulsed Doppler velocimetry of the brachial artery and strain gauge mercury-in silastic plethysmography of the forearm. In addition the systolic time intervals including preejection period (PEP) and left ventricular time (LVET) were also measured after drug administration. Acute oral medroxalol produced a rapid and significant decrease in systolic and diastolic blood pressure and in heart rate. Concomitantly a significant increase was observed in brachial artery diameter (p less than 0.05), blood velocity and flow (p less than 0.01); forearm vascular resistance decreased (p less than 0.001) but forearm venous tone was unchanged. Lastly medroxalol prolonged PEP but shortened LVET corrected for heart rate. These results demonstrate a rapid antihypertensive action of a single dose of medroxalol with a dilation of the arteries but not of the veins of the forearm and a discrepant effect on the systolic time intervals.