ARBs

Angiotensin II receptor blockers (ARBs) are a class of antihypertensive medications that selectively antagonize the angiotensin II type 1 (AT1) receptor. By blocking AT1 receptors in vascular smooth muscle and other tissues, ARBs prevent angiotensin II–mediated vasoconstriction and aldosterone release, leading to vasodilation, reduced systemic vascular resistance, and lower blood pressure.

ARBs also reduce intraglomerular pressure, which can protect renal function in diabetic nephropathy, and they decrease aldosterone-driven sodium retention and sympathetic activity. They are generally well tolerated and provide a useful alternative for patients who cannot take ACE inhibitors.

Indications for ARBs include hypertension as first-line or add-on therapy, heart failure with reduced ejection fraction, and certain post–myocardial infarction settings. They are also used to treat proteinuric kidney diseases, particularly in patients who cannot tolerate ACE inhibitors. ARBs can be used alone or in combination with other antihypertensives as part of a comprehensive cardiovascular risk reduction strategy.

Adverse effects and contraindications: ARBs typically cause fewer cough and angioedema than ACE inhibitors, but angioedema can occur. Common adverse effects include dizziness, hyperkalemia, and hypotension. They should not be used during pregnancy due to teratogenic risk, and caution is advised in renal impairment. They may increase potassium levels, especially when used with potassium-sparing diuretics or NSAIDs.

Pharmacokinetics and interactions: most ARBs are taken orally. Losartan is a prodrug; others like valsartan are not. Metabolism is hepatic with renal and fecal routes of excretion, and half-lives vary by agent. Interactions include reduced antihypertensive effect with NSAIDs and increased risk of hyperkalemia with potassium-sparing therapies. Concomitant use with aliskiren is generally discouraged in patients with diabetes or CKD.

Common agents include losartan, valsartan, irbesartan, candesartan, telmisartan, and olmesartan.