Angiotensin II Receptor Antagonists Role in Arterial Hypertension

Angiotensin II receptor blockers represent a class of effective and well tolerated orally active antihypertensive drugs. Activation of AT(1) receptors leads to vasoconstriction, stimulation of the release of catecholamines and antidiuretic hormone and promote growth of vascular and cardiac muscle. AT(1) receptor blockers antagonise all those effects. Losartan was the first drug of this class marketed, shortly followed by valsartan, irbesartan, telmisartan, candesartan, eprosartan and others on current investigation. All these drugs have the common properties of blockading the AT(1) receptor thereby relaxing vascular smooth muscle, increase salt excretion, decrease cellular hypertrophy and induce antihypertensive effect without modifying heart rate or cardiac output. Most of the AT(1) receptor blockers in use controlled blood pressure during the 24 h with a once-daily dose, without evidence of producing tolerance to the antihypertensive effect and being with low incidence of side effects even at long term use. Monotherapy in mild-to-moderate hypertension controls blood pressure in 40 to 50% of these patients; when a low dose of thiazide diuretic is added, 60-70% of patients are controlled. The efficacy is similar to angiotensin-converting enzyme (ACE) inhibitors, diuretics, calcium antagonists and beta-blocking agents. AT(1) receptor blockers are specially indicated in patients with hypertension who are being treated with ACE inhibitors and developed side effects such as, cough or angioedema. The final position in the antihypertensive therapy in this special population and other clinical situations, such as left ventricular hypertrophy, heart failure, diabetes mellitus and renal disease, has to be determined in large prospective clinical trials, some of which are now being conducted and seem promising.