Angiotensin II receptor blockers

An overview of Angiotensin II receptor blockers (ARBs) in medical treatment

Angiotensin II receptor blockers (ARBs) are a class of drugs primarily used to treat hypertension (high blood pressure) and heart failure. They work by blocking the effects of angiotensin II, a potent vasoconstrictor, thereby relaxing blood vessels and reducing blood pressure. ARBs are also used in the management of chronic kidney disease and diabetic nephropathy.

Mechanism of Action

ARBs selectively block the binding of angiotensin II to the AT1 receptor, which is found in various tissues such as vascular smooth muscle, adrenal gland, and kidneys. By inhibiting this interaction, ARBs prevent the vasoconstrictive and aldosterone-secreting effects of angiotensin II, leading to vasodilation and decreased blood pressure.

Clinical Uses

ARBs are indicated for:

• Hypertension: ARBs are effective in lowering blood pressure and are often used when patients are intolerant to ACE inhibitors.
• Heart Failure: They are used to improve symptoms and reduce mortality in patients with heart failure, particularly when ACE inhibitors are not tolerated.
• Chronic Kidney Disease: ARBs help in slowing the progression of kidney disease, especially in patients with diabetic nephropathy.
• Myocardial Infarction: Post-myocardial infarction, ARBs can be used to improve survival and reduce the risk of heart failure.

Commonly Used ARBs

Some of the commonly prescribed ARBs include:

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

Side Effects

ARBs are generally well-tolerated, but they can cause side effects such as:

• Dizziness
• Hyperkalemia: Elevated potassium levels in the blood.
• Renal impairment: Worsening of kidney function in susceptible individuals.
• Angioedema: Although rare, it can occur, especially in patients with a history of angioedema with ACE inhibitors.

Comparison with ACE Inhibitors

While both ARBs and ACE inhibitors target the renin-angiotensin-aldosterone system, they do so at different points. ACE inhibitors block the conversion of angiotensin I to angiotensin II, while ARBs block the action of angiotensin II at the receptor level. ARBs are less likely to cause a persistent dry cough, a common side effect of ACE inhibitors.

Also see

• Renin-angiotensin-aldosterone system
• Hypertension
• Heart failure
• ACE inhibitors
• Diabetic nephropathy