Atenolol

Atenolol is a cardioselective beta-adrenergic receptor blocker (beta-1 selective) used to treat various cardiovascular conditions. By blocking beta-1 receptors in the heart, it reduces heart rate, decreases myocardial contractility, and lowers blood pressure. It also diminishes renin release from the kidneys, contributing to its antihypertensive effect. Atenolol is relatively hydrophilic and is primarily eliminated by the kidneys, with minimal hepatic metabolism. In adults with normal renal function, the elimination half-life is about 6 to 7 hours, but clearance is reduced in renal impairment. It can be given orally or by intravascular injection.

Common indications include essential hypertension, angina pectoris due to coronary artery disease, certain supraventricular arrhythmias, and to reduce mortality after myocardial infarction. Dosing is individualized and depends on the condition being treated and patient response. Atenolol tablets are typically available in 25, 50, and 100 mg strengths.

Adverse effects are usually related to beta-blockade and may include bradycardia, fatigue, dizziness, hypotension, and cold extremities. Less commonly, induced bronchospasm can occur in patients with reactive airway disease, given incomplete selectivity in some individuals. Atenolol can mask signs of hypoglycemia and should be used with caution in diabetes. Contraindications include severe bradycardia, advanced heart block without a functioning pacemaker, cardiogenic shock, and uncompensated heart failure.

Drug interactions include additive heart-rate–lowering effects with non-dihydropyridine calcium channel blockers (such as verapamil or diltiazem), and increased risk of hypoglycemia with insulin or other antidiabetic agents. Atenolol crosses the placenta and may affect the fetus; its use in pregnancy is generally avoided unless clearly beneficial. It is excreted in breast milk, so breastfeeding considerations are advised.