Pharmacological Profile of Carvedilol as a β-Blocking Agent with Vasodilating and Hypotensive Properties

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Abstract
Summary: Carvedilol is a new β-receptor blocking and vasodilating drug that is presently undergoing clinical trials in hypertension and coronary heart disease. In this article, the pharmacodynamic properties of carvedilol are compared with those of standard drugs. The β-blocking activity was characterized in isolated organs and in conscious rats, rabbits, and dogs. For the β1-blockade in guinea pig atria, the pA10 values were 7.44 ± 0.16 for carvedilol and 6.77 ± 0.08 for propranolol. Carvedilol is a noncardioselective β-blocker. The i.v. doses that inhibited the tachycardia by 50% induced by 1 μg/kg isoprenaline were 62 μg/kg in dogs, 138 μg/kg in rabbits and 841 μg/kg in rats. In rabbits carvedilol was slightly more active and in rats less active than propranolol. In all models, carvedilol was much more active than labetalol or prizidilol. In contrast to propranolol, carvedilol relaxed rat aortic strips. A dose-dependent decrease in arterial blood pressure was seen in different in vivo models. The total peripheral and coronary resistance were decreased in conscious dogs. The doses required for both β-blockade and decrease in blood pressure were in the same range. The drug was also active after oral administration. There is no hint for development of tolerance.