Adrenergic Antagonists: Pharmacological Actions of β-Receptor Blockers

β-receptor blockers predominantly exhibit cardiovascular effects by inhibiting catecholamine-induced sympathetic responses. They decrease heart rate, contractility, and cardiac output leading to cardiac depression.

This can potentially result in life-threatening bradycardia and heart failure.

Therapeutically, β-blockers are utilized as mild antihypertensives, and for treating angina pectoris and cardiac arrhythmias.

Nonselective β-blockers inhibit the β₂-receptors in bronchial smooth muscle, causing bronchoconstriction. This can be potentially fatal to patients with asthma or obstructive lung diseases.

They help control exaggerated sympathetic responses in pheochromocytoma and thyrotoxicosis. They are useful in chronic migraine prevention and act as an anti-anxiety agent.

Further, β-blockers like propranolol impede sympathetically induced lipolysis and insulin release.

They also treat chronic open-angle glaucoma by reducing aqueous humor production to lower intraocular pressure.

Additionally, propranolol is the drug of choice for treating severe infantile hemangioma.

β-blocker treatment can also lead to CNS-related effects like fatigue, forgetfulness, sleep disturbances and depression.