Carvedilol (Coreg, SmithKline Beecham), a nonselective beta-blocker with alpha-blocking and antioxidant properties, is the first beta-blocker approved for use in Canada for the management of congestive heart failure (CHF). Carvedilol is indicated in patients with mild to moderate heart failure (NewYork Heart Association [NYHA] class II and III) refractory to conventional therapy with diuretics and angiotensin-converting enzyme (ACE) inhibitors. Although only approved for use in Canada for CHF, carve-dilol, as with other beta-blockers, also possesses antihypertensive and antianginal activities, and is approved for use for these indications in other countries. buy prednisone
Although carvedilol is considered a nonselective beta-antagonist that blocks both beta-1 and beta-2 receptors, it is mildly selective for the beta-1 receptor . Carvedilol also possesses alpha-blocking or vasodilating activity (similar to that of labetalol), which contributes to its beneficial effects in both hypertension and heart failure. The ratio of beta to alpha blockade is of the order of 10:1, with carvedilol demonstrating 50% less alpha blockade than labetalol . The additional vasodilatory effects of carvedilol have several advantages in the management of hypertension, coronary artery disease and CHF. Alpha blockade diminishes some of the undesirable adverse effects of beta-blockers, such as myocardial depression and peripheral vasoconstriction. In contrast to propranolol, the administration of single doses of carvedilol is not associated with reductions in cardiac output or increases in peripheral vascular resistance. While propranolol increases pulmonary capillary wedge pressure (PCWP) as a function of its negative inotropic properties, carvedilol decreases PCWP secondary to its vasodilatory actions . Furthermore, the undesirable effects of direct-acting vasodilators, such as reflex tachycardia and fluid retention, are also blunted by the combination of beta- and alpha-blocking properties.