Definition

A synthetic phenylethylamine that mimics the sympathomimetic actions of the endogenous norepinephrine. Norepinephrine acts directly on the alpha- and beta-adrenergic receptors. Clinically, norepinephrine is used as a peripheral vasoconstrictor that causes constriction of arterial and venous beds via its alpha-adrenergic action. It is also used as a potent inotropic and chronotropic stimulator of the heart mediated through its beta-1 adrenergic action.