Antihypertensive drugs are currently divided into five major categories: diuretics, beta-blockers, calcium channel blockers, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers. 1. Diuretics act through sodium excretion, reducing extracellular volume and lowering peripheral vascular resistance to lower blood pressure. 2. beta-blockers act by inhibiting the central and peripheral RAS systems and hemodynamic autoregulation mechanisms. 3. 3. calcium channel blockers reduce the contractile responsiveness of resistance vessels by blocking the entry of extracellular calcium ions into vascular smooth muscle cells via calcium channels. 4. angiotensin-converting enzyme inhibitors lower blood pressure mainly by inhibiting peripheral and tissue angiotensin-converting enzymes, resulting in reduced angiotensin II production. 5. angiotensin II receptor blockers lower blood pressure by blocking tissue angiotensin II receptor subtypes. angiotensin II receptor subtype, thus more effectively blocking the water and sodium retention, vasoconstriction and remodeling effects of angiotensin II.