Angiotensin ii receptor antagonist

Angiotensin II Receptor Antagonist

Angiotensin II receptor antagonists, also known as angiotensin II receptor blockers (ARBs), are a class of drugs primarily used to treat high blood pressure (hypertension) and heart failure. They work by blocking the effects of angiotensin II, a potent vasoconstrictor, thereby relaxing blood vessels and reducing blood pressure.

Mechanism of Action

Angiotensin II is a hormone that plays a crucial role in the renin-angiotensin system, which regulates blood pressure and fluid balance. It exerts its effects by binding to angiotensin II receptors, primarily the AT1 receptor, located on the surface of various cell types, including vascular smooth muscle cells.

ARBs selectively block the binding of angiotensin II to the AT1 receptor, preventing vasoconstriction and the release of aldosterone, a hormone that promotes sodium and water retention. This leads to vasodilation, decreased blood volume, and ultimately, lower blood pressure.

Clinical Uses

ARBs are commonly prescribed for:

• Hypertension: ARBs are effective in lowering blood pressure and are often used when patients cannot tolerate ACE inhibitors due to side effects such as cough.
• Heart failure: They help reduce the workload on the heart by lowering blood pressure and decreasing fluid retention.
• Chronic kidney disease: ARBs can slow the progression of kidney disease, particularly in patients with diabetes.
• Myocardial infarction: Post-heart attack, ARBs can help improve survival and reduce the risk of further cardiovascular events.

Commonly Used ARBs

Some of the widely used angiotensin II receptor antagonists include:

• Losartan
• Valsartan
• Irbesartan
• Candesartan
• Telmisartan
• Olmesartan

Side Effects

While ARBs are generally well-tolerated, they can cause side effects in some individuals. Common side effects include:

• Dizziness
• Hyperkalemia (elevated potassium levels)
• Fatigue
• Headache

Rarely, ARBs can cause more serious side effects such as kidney dysfunction or angioedema, although the latter is less common compared to ACE inhibitors.

Contraindications

ARBs should be used with caution or avoided in certain populations, including:

• Pregnant women: ARBs can cause fetal harm and are contraindicated during pregnancy.
• Patients with bilateral renal artery stenosis: ARBs can worsen kidney function in these individuals.

Also see

• Renin-angiotensin system
• ACE inhibitors
• Hypertension
• Heart failure
• Chronic kidney disease

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