Comparison of the haemodynamic profiles of the hypotensive action of verapamil and carvedilol.

Comparative haemodynamic investigations with carvedilol and verapamil were carried out on conscious, instrumented dogs. Arterial blood pressure, right atrial pressure (RAP), cardiac output (CO), heart rate, stroke volume and total peripheral resistance (TPR) were determined after intravenous (i.v.) injection of incremental doses (0.01-3 mg/kg) of the drugs. Carvedilol reduced the blood pressure in a dose-dependent manner, concomitant with a reduction in TPR. The RAP and the CO were not affected, indicating that arterial vasodilatation was induced by carvedilol. Verapamil showed a decrease in the blood pressure with a reduction of CO and SV. Moreover, at high doses the RAP was increased, indicating a reduction of the cardiac performance. Thus, in our experimental model remarkable differences between the haemodynamic effects of i.v. injections of carvedilol and verapamil have been observed, whereas after oral administration blood pressure also decreases after verapamil due to a reduction of TPR.