RAS inhibition in hypertension

Drugs that inhibit the renin-angiotensin system (RAS), namely angiotensin-converting enzyme inhibitors (ACE-I) and angiotensin receptor antagonists (ARA) are gaining increasing popularity as initial medications for the management of hypertensive patients. In the year 2002, ACE-I were the most commonly prescribed drugs for the treatment of hypertension in USA. Although their antihypertensive efficacy as monotherapy is similar to other antihypertensive agents, they have the advantage of better tolerability, limited side effects and a favorable metabolic profile. When compared to other antihypertensive agents (diuretics, beta-adrenergic blockers and calcium antagonists) in large clinical trials, ACE-I and ARA provided no additional advantages regarding improvement in cardiovascular and total mortality. With the exception of the superiority of ARA in prevention of stroke, RAS inhibitors have no advantage over other agents in prevention of other cardiovascular morbid events, namely, heart failure (though ACE-I are superior to calcium antagonists), coronary heart disease and total cardiovascular events. However, there is the possibility that these agents have other benefits beyond blood pressure lowering. At equal degrees of blood pressure reduction, RAS inhibitors prevent or delay the development of diabetes mellitus and provide better end-organ protection, kidneys, blood vessels and the heart when compared with other antihypertensive agents. The combined use of ACE-I and ARA is particularly useful in organ protection. RAS inhibitors are specifically indicated in the treatment of hypertension in patients with impaired left ventricular systolic function, diabetes, proteinuria, impaired kidney function, myocardial infarction, multiple cardiovascular risk factors and possibly elderly patients. The main limitation of the ACE-I is cough and rarely angioedema. Elderly patients or those who are volume depleted or receiving large doses of diuretics or in heart failure are liable to develop hypotensive reaction and/or deterioration in kidney function.