beta-adrenergic antagonist An agent that binds to but does not activate β-adrenergic receptors thereby blocking the actions of endogenous or exogenous β-adrenergic agonists. β-Adrenergic antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches and anxiety. adrenergic antagonist beta-adrenergic drug