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Angiotensin Receptor BlockersEdit

Angiotensin receptor blockers (ARBs) are a well-established class of cardiovascular and kidney drugs that work by interrupting the body’s main salt-and-blood pressure system, the renin–angiotensin–aldosterone system (RAAS). By blocking the AT1 receptor, which is the primary site where angiotensin II exerts vasoconstrictive and pro-remodeling effects, ARBs promote vasodilation, reduce aldosterone secretion, and lower blood pressure. They are often favored when patients cannot tolerate ACE inhibitors, because they tend to provoke fewer bothersome side effects such as cough or angioedema. Notable members of this class include losartan, valsartan, irbesartan, candesartan, telmisartan, olmesartan, and azilsartan. Beyond hypertension, ARBs have proven benefits in several other conditions, and they remain a frequent choice for clinicians seeking a balance of efficacy, tolerability, and cost.

ARBs are a key option in the management of several commonly encountered medical problems. They are used for hypertension, heart failure with reduced ejection fraction (HFrEF), and to protect kidney function in certain types of nephropathy, including diabetic nephropathy. They are also used after myocardial infarction in some patients to improve outcomes and reduce remodeling of the heart. In clinical practice, ARBs are frequently compared with angiotensin-converting enzyme as an alternative when cough or angioedema limits ACE inhibitor use. The pharmacologic profile—effective blood pressure lowering with a relatively favorable side effect spectrum—has made ARBs a core component of guideline-directed medical therapy for a broad range of patients, from primary prevention to high-risk groups.

Mechanism of action

ARBs selectively block the AT1 receptor, the primary receptor mediating the vasoconstrictive and pro-fibrotic actions of angiotensin II. This receptor blockade reduces vasoconstriction, decreases aldosterone release, and mitigates pathologic remodeling in the heart, vessels, and kidneys. In doing so, ARBs help lower blood pressure and protect end-organ function in conditions driven by RAAS overactivity. For a more detailed connection to the receptor, see angiotensin II receptor type 1 and the broader system they interact with, the Renin–angiotensin–aldosterone system.

In addition to hemodynamic effects, ARBs can blunt inflammation and fibrosis in settings of chronic injury, which contributes to organ protection in heart and kidney disease. Their pharmacologic profile can be advantageous when a patient requires RAAS blockade but is intolerant of ACE inhibitors, as ARBs generally do not cause ACE-inhibitor–associated cough and have a lower (though not zero) risk of angioedema.

Medical uses

  • Hypertension: ARBs lower blood pressure and reduce long-term cardiovascular risk in adults with elevated blood pressure.
  • Heart failure with reduced ejection fraction (HFrEF): ARBs improve symptoms, reduce hospitalizations, and may improve survival in patients who cannot tolerate ACE inhibitors or in whom such therapy is indicated.
  • Post-myocardial infarction: In certain patients, ARBs reduce remodeling and adverse outcomes after a heart attack.
  • Diabetic and non-diabetic nephropathy: ARBs lower intraglomerular pressure and proteinuria, providing renal protection in various forms of kidney disease, particularly in patients with diabetes.
  • Other vascular or cardiac conditions: ARBs may be used as part of combination therapy for selected patients with resistant hypertension or certain forms of left ventricular remodeling.

Notable agents in this class and their general clinical roles include losartan and valsartan as widely used first-line options, with others such as irbesartan, candesartan, telmisartan, olmesartan, and azilsartan playing important roles in diverse patient populations. The choice among ARBs often hinges on tolerability, dosing convenience, kidney function considerations, and cost considerations, including the availability of generics.

Safety, adverse effects, and tolerability

  • Hyperkalemia: Like other RAAS inhibitors, ARBs can raise serum potassium, particularly in patients with reduced kidney function, diabetes, or concomitant potassium-sparing therapies.
  • Kidney function: ARBs can affect kidney function in certain contexts; monitoring is advised in patients with chronic kidney disease, dehydration, or when NSAIDs are used chronically.
  • Angioedema and cough: ARBs have a lower risk of angioedema and cough than ACE inhibitors, but angioedema can still occur, and ARBs are generally avoided in people with a history of ACE-inhibitor–associated angioedema.
  • Pregnancy: ARBs are contraindicated in pregnancy due to fetal harm; they are typically discontinued if pregnancy is planned or detected.
  • Other adverse effects: Dizziness, fatigue, and rare renal or hepatic adverse events have been reported with ARBs, depending on the agent and patient population.

ARBs are often praised for tolerability, which has clinical and economic ramifications: better adherence, fewer discontinuations, and the potential for sustained blood pressure control in diverse patient groups. As with other RAAS blockers, careful patient selection and monitoring—especially in the context of kidney function and electrolyte balance—are essential.

Efficacy and comparative effectiveness

Clinical trials and meta-analyses have established that ARBs provide cardiovascular and renal protection comparable to other effective antihypertensive strategies in many settings, with some variability across populations and specific drugs. Trials such as ONTARGET compared an ARB with an ACE inhibitor and found similar cardiovascular outcomes, while combination therapy with both classes increased adverse events and did not improve outcomes. This has helped shape guideline recommendations against routine combination RAAS blockade.

In practice, the choice between ARBs and ACE inhibitors often centers on tolerability and patient preference. For patients who experience cough or angioedema with an ACE inhibitor, an ARB offers a well-supported alternative with substantial protective effects. For certain high-risk scenarios—such as post-MMI LV remodeling—some clinicians may favor ACE inhibitors based on trial data in specific subgroups, though ARBs remain a strong option when ACE inhibitors are not tolerated.

From a policy and cost perspective, the widening availability of generic ARBs supports access to effective therapy at a lower ongoing cost, a factor that matters for health systems emphasizing value-based care and for patients managing out-of-pocket expenses.

History and development

The RAAS-blocking strategy emerged as researchers identified how angiotensin II promotes vasoconstriction, sodium retention, and tissue remodeling. The first ARB to reach widespread clinical use was developed in the 1990s, with subsequent agents introduced over the following decades. The class has since become a mainstay in guidelines for hypertension and kidney protection, balancing efficacy with a favorable tolerability profile.

See also