Angiotensin-II receptor antagonists: a new class of antihypertensive agents

Pharmacologic agents that attenuate the influence of the renin-angiotensin-aldosterone system are known to reduce systemic arterial blood pressure through vasodilatory action and enhanced renal clearance of sodium and water. Angiotensin-converting enzyme inhibitors are known to antagonize the renin-angiotensin-aldosterone system through their ability to inhibit conversion of angiotensin I to angiotensin II. A new class of antihypertensive agents, angiotensin-II receptor antagonists, has recently been developed. These agents specifically block the receptor for angiotensin II, thereby limiting angiotensin II-mediated vasoconstriction and reducing aldosterone secretion. These effects result in a reduction in systemic arterial blood pressure through reduced vascular tone and enhanced sodium and water clearance. Clinical trials have demonstrated the efficacy of these agents in reducing blood pressure. These new antihypertensive agents also have uricosuric actions and are well tolerated, with a low incidence of cough and angioedema, side effects that are seen with angiotensin-converting enzyme inhibitors. Clinical trials are underway to see if these drugs will be useful in the treatment of diseases other than hypertension, such as congestive heart failure and chronic renal disease.