Atenolol + hydrochlorothiazide + amlodipine + hydralazine

Atenolol + hydrochlorothiazide + amlodipine + hydralazine is a combination of four antihypertensive agents, each with a distinct mechanism of action, used together to manage high blood pressure (hypertension) in patients who require multiple medications for adequate control. Atenolol is a beta-1 selective adrenergic receptor blocker that reduces heart rate and cardiac output. Hydrochlorothiazide is a thiazide diuretic that lowers blood pressure by promoting sodium and water excretion via the kidneys. Amlodipine is a calcium channel blocker that relaxes vascular smooth muscle, leading to vasodilation and reduced peripheral resistance. Hydralazine is a direct-acting vasodilator that primarily relaxes arteriolar smooth muscle, further decreasing systemic vascular resistance. This multi-drug regimen may be considered in resistant hypertension or when monotherapy or dual therapy does not achieve target blood pressure[2][4][7].