Angiotensin II receptor antagonist

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Image:Losartan structure.png Angiotensin II receptor antagonists, also known as angiotensin receptor blockers (ARBs), AT₁-receptor antagonists or sartans, are a group of pharmaceuticals which modulate the renin-angiotensin-aldosterone system. Their main use is in hypertension (high blood pressure), diabetic nephropathy (kidney damage due to diabetes) and congestive heart failure.

1 Mode of action
2 Uses
3 Adverse effects
4 Members
5 References

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Mode of action

These substances are AT₁-receptor antagonists – that is, they block the activation of angiotensin II AT₁ receptors. Blockade of AT₁ receptors directly causes vasodilation, reduces secretion of vasopressin, reduces production and secretion of aldosterone, amongst other actions – the combined effect of which is reduction of blood pressure.

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Uses

Angiotensin II receptor antagonists are primarily used for the treatment of hypertension where the patient is intolerant of ACE inhibitor therapy. They do not inhibit the breakdown of bradykinin or other kinins, and are thus only rarely associated with the persistent dry cough that commonly limits ACE inhibitor therapy. More recently, they have been used for the treatment of heart failure in patients intolerant of ACE inhibitor therapy, particularly candesartan. Irbesartan and losartan have trial data showing benefit in hypertensive patients with type II diabetes, and may delay the progression of diabetic nephropathy.

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Adverse effects

This class of drugs is usually well-tolerated, with common adverse drug reactions (ADRs) including: dizziness, headache, and/or hyperkalaemia. Infrequent ADRs associated with therapy include: first dose orthostatic hypotension, rash, diarrhoea, dyspepsia, abnormal liver function, muscle cramp, myalgia, back pain, insomnia, decreased haemoglobin levels, renal impairment, pharyngitis, and/or nasal congestion. (Rossi, 2006)

While one of the main rationales for the use of this class is the avoidance of dry cough associated with ACE inhibitor therapy, it may still rarely occur. Additionally, there is also a small risk of cross-reactivity in patients who have experienced angioedema with ACE inhibitor therapy. (Rossi, 2006)

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