An extended-release capsule formulation containing the phosphate salt of carvedilol, a nonselective beta-adrenergic blocking agent with alpha 1-adrenergic blocking activity. Carvedilol is a racemic mixture; the S(-) enantiomer non-selectively binds to and blocks beta-adrenergic receptors, exerting negative inotropic and chronotropic effects, leading to a reduction in cardiac output. Both R(+) and S(-) enantiomers bind to and block alpha 1-adrenergic receptors with equal potency, causing vasodilation and a reduction in peripheral vascular resistance. This agent has no intrinsic sympathomimetic activity.