Beta adrenergic blocking agents prevent stimulation of the beta adrenergic receptors at the nerve endings of the sympathetic nervous system and therefore decrease the activity of the heart. They block sympathetic stimulation of the heart and reduce systolic pressure, heart rate, cardiac contractility and output, so decrease myocardial oxygen demand and increase exercise tolerance.
Beta adrenergic blocking agents are used to treat angina, control abnormal heart rhythms and to reduce high blood pressure. However, non-cardioselective beta blockers can cause significant bronchial constriction and could be harmful especially in patients with respiratory conditions such as asthma or chronic obstructive pulmonary disease.
