aspirin + isosorbide mononitrate + atenolol + enalapril

This is a fixed-dose combination of four cardiovascular drugs: - **Aspirin** is an antiplatelet agent that irreversibly inhibits cyclooxygenase (COX), reducing thromboxane A2 production and thereby decreasing platelet aggregation. It helps prevent blood clots, lowering the risk of heart attack and stroke. - **Isosorbide mononitrate** is a nitrate vasodilator that acts as a prodrug for nitric oxide, relaxing vascular smooth muscle (mainly veins) to reduce cardiac preload and relieve angina. - **Atenolol** is a selective beta-1 adrenergic receptor blocker (beta-blocker) that decreases heart rate, myocardial contractility, and blood pressure, reducing cardiac workload and oxygen demand. - **Enalapril** is an angiotensin-converting enzyme (ACE) inhibitor prodrug. Its active metabolite enalaprilat inhibits ACE, reducing the formation of angiotensin II—a potent vasoconstrictor—leading to vasodilation, reduced blood pressure, decreased afterload/preload on the heart, and improved outcomes in hypertension and heart failure. This combination targets multiple mechanisms involved in coronary artery disease management—antiplatelet action to prevent thrombosis; nitrate-induced vasodilation for angina relief; beta-blockade for rate/blood pressure control; ACE inhibition for further blood pressure reduction and organ protection. Such combinations are used in secondary prevention after myocardial infarction or in patients with high cardiovascular risk[4][5][6][7][8].