Beta-blockers and hypertension

While there is general agreement on the natural history, pathology, and pathophysiology of hypertension, there continues to be controversy over the selection of specific antihypertensive agents. All antihypertensive agents will, by definition, lower blood pressure, and factors beyond side effects and other difficulties associated with therapy form the basis of selecting specific agents. One of these factors is the effect of a given drug on core organ function. Propranolol was the first beta-adrenoceptor-blocking agent introduced for the treatment of hypertension. Initiation of therapy with propranolol may result in a decline in blood pressure more at the expense of cardiac function due to a concomitant rise in total peripheral resistance. Furthermore, propranolol may result in a decline in both glomerular filtration rate (GFR) and renal blood flow (RBF). In contrast, cardioselective beta-blockers or those with intrinsic sympathomimetic activity may not adversely affect renal function. It had been predicted that nadolol, a noncardioselective beta-blocker without intrinsic sympathomimetic activity, should result in decreased renal function. In contrast, observations demonstrated a preservation or improvement in both RBF and GFR, suggesting the presence of an alternative effective mechanism. Recent additions to the beta-adrenolytic group of antihypertensive agents include drugs with concurrent beta-blockade and vasodilation. This vasodilatation may be achieved through agonist properties resulting in lesser increases in vasomotor tone and smaller, if any, decreases in cardiac output. Alternatively, vasodilation may be achieved by concomitant alpha-adrenoceptor blockade, such as with labetalol. This agent preserves GFR and RBF during therapy of hypertension, in patients with normal as well as diminished renal function and hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)