Pharmacology of carvedilol: Rationale for use in hypertension, coronary artery disease, and congestive heart failure

Carvedilol is a novel, multiple-action cardiovascular drug that is currently approved in many countries for the treatment of hypertension. The reduction in blood pressure produced by carvedilol results primarily from β-adrenoceptor blockade and vasodilation, the latter resulting from α1-adrenoceptor blockade. These actions, as well as several of the other activities of carvedilol, are associated with cardioprotection in animal models that occurs to a degree that is greater than that observed with other drugs. The multiple actions of carvedilol may also provide the underlying rationale for the use of the drug in the treatment of coronary artery disease and congestive heart failure. By virtue of being both a beta-blocker and a vasodilator, carvedilol significantly decreases myocardial work by reducing all three components of myocardial oxygen demand, namely, heart rate, contractility, and wall tension. The vasodilatory effects of carvedilol reduce afterload, and the resulting decrease in impedance to left ventricular ejection offsets the negative inotropic effect that would normally result from beta-blockade. As a consequence, stroke volume and cardiac output are maintained or even increased in animals and in patients with congestive heart failure who are treated with carvedilol. Carvedilol and several of its metabolites are potent antioxidants, and this activity may account, in part, for the cardioprotective effects of the drug observed in animal models of acute myocardial ischemia and, in theory, could also serve to protect the myocardium of patients with hypertension, coronary artery disease, and congestive heart failure, in which oxidative stress is now recognized to occur. The antioxidant effects of carvedilol may both inhibit the direct cytotoxic actions of reactive oxygen radicals and prevent oxygen-radical induced activation of transcription factors and genes associated with inflammatory and remodeling processes. Accordingly, carvedilol inhibits the gene expression of the intracellular adhesion molecule-1 (ICAM-1), an adhesion molecule for polymorphonuclear leukocytes, which typically infiltrate the myocardium under conditions of ischemia and may exacerbate ischemic injury. The antioxidant activity of carvedilol has been shown to inhibit the oxidation of low density lipoprotein (LDL) in vitro, thereby preventing the formation of this cytotoxic and atherogenic form of LDL. It follows, therefore, that in animal models of hyperlipidemia, carvedilol attenuates aortic lipid accumulation and decreases the aortic content of monocytes and foam cells, and at the same time it has been shown to preserve endothelial integrity and function. These actions of carvedilol are not shared by other beta-blockers or by other drugs currently used in the management of hypertension, coronary artery disease, or congestive heart failure. The multiple actions of carvedilol may provide the underlying pharmacologic rationale for the use of this drug in the treatment of patients with coronary artery disease or congestive heart failure, and these actions may account, at least in part, for the reduction in mortality produced by carvedilol in clinical trials involving patients with congestive heart failure. Likewise, these actions of carvedilol may also provide protection, beyond that afforded from reduction in blood pressure, against secondary organ damage in hypertensive patients treated with the drug.