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These drugs, also called angiotensin II receptor antagonists, inhibit the effects of angiotensin II, whereas ACE inhibitors block the formation of angiotensin II. In this way, it prevents the constriction of blood vessels and retention of salt and water, thereby lowering blood pressure.
These drugs are also vasodilators that have many of the same features as the ACE inhibitors, and are also of particular value in patients with heart failure and diabetics with kidney disease. The angiotensin II receptor blockers should also be avoided during pregnancy and in patients with high blood levels of potassium.
Unlike ACE inhibitors, these drugs do not cause an increase in bradykinin and do not produce a dry cough and angioedema. The benefits of ARBs are very similar to Ace inhibitors, without the problems of cough, taste disturbance and angioedema.
A few angiotensin II receptor blockers:
- Losartan in Cozaar
- Irbesartan in Aprovel
- Telmisartan in Micardis
Indications for use as anti-hypertensive drug:
- ACE inhibitor may cause cough or angioedema.
- Heart failure in patients unable to take ACE inhibitors
- Chronic kidney disease
- Safe for diabetic patients, and protect the kidneys
- Prevention of stroke and dementia
Contraindications:
- Pregnancy, or if planning to become pregnant
- Hyperkalaemia – high blood levels of potassium
- Bilateral renal artery stenosis – narrowing of the arteries supplying the kidneys, on both sides
Possible side-effects:
Side-effects and allergic reactions are rare. This may lead to better adherence to treatment. One advantage over ACE inhibitors is that it does not cause a dry cough as a side effect. (About 10 to 20 % of patients using ACE inhibitors may develop a dry, hacking cough.)
ARBs generally have placebo-like tolerability and are very useful in patients with mutliple drug intolerances.
Possible drug interactions:
Similar to ACE inhibitors
Article written by Dr Kathleen Coetzee, MBChB
Reviewed by Prof Brian Rayner, head of the division of nefhrology and hypertension, University of Cape Town and Groote Schuur Academic Hospital, December 2010
