Norepinephrine bitartrate acts directly on the α- and β-adrenergic receptors. Norepinephrine Bitartrate is a bitartrate salt of norepinephrine, a synthetic phenylethylamine that mimics the sympathomimetic actions of the endogenous norepinephrine. 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.