B2receptorantagonister

Beta₂-receptor antagonists, commonly referred to as beta-blockers, are a class of medications primarily used to manage conditions involving excessive sympathetic nervous system activity, particularly those affecting the heart and blood vessels. These drugs selectively or non-selectively block beta₂-adrenergic receptors, which are found in various tissues, including the lungs, heart, blood vessels, and skeletal muscles. By inhibiting these receptors, beta₂-receptor antagonists reduce the effects of adrenaline (epinephrine) and noradrenaline (norepinephrine), leading to decreased heart rate, blood pressure, and myocardial contractility.

Beta₂-receptor antagonists are widely prescribed for conditions such as hypertension, angina pectoris, arrhythmias, and heart failure. They are also used in the management of migraines, anxiety disorders, and certain types of tremors. In asthma and other obstructive lung diseases, selective beta₂-agonists are preferred over antagonists due to the potential for beta₂-receptor antagonists to cause bronchoconstriction by blocking the beneficial effects of endogenous adrenaline on the lungs.

The classification of beta₂-receptor antagonists includes cardioselective agents, which primarily affect beta₁-receptors in the heart, and non-selective agents, which impact both beta₁- and beta₂-receptors. Examples of cardioselective beta-blockers include metoprolol and atenolol, while propranolol is a non-selective beta-blocker. The choice of medication depends on the patient’s condition, medical history, and potential side effects, such as fatigue, dizziness, or bronchospasm.

Beta₂-receptor antagonists are generally well-tolerated when used appropriately, but abrupt discontinuation can lead to rebound hypertension or cardiac ischemia. Therefore, tapering under medical supervision is recommended. Contraindications include severe bradycardia, heart block, and asthma, among others. As with all medications, individual responses may vary, and close monitoring by a healthcare provider is essential.