Basis for cardiovascular therapy with beta-blocking agents.

Beta blockade is the cornerstone of the therapy for ischemic heart disease and is increasingly used as first-line therapy for hypertension. Three chief properties that distinguish among different beta blockers are cardioselectivity, intrinsic sympathomimetic activity (ISA) and pharmacokinetic differences. Cardioselectivity appears to confer some advantages, although there is a potential and serious danger in giving any beta blocker to patients with asthma, heart failure or active peripheral disease. The degree of ISA in different beta blockers may vary. This property may diminish the degree of cardiac depression caused by beta blockade, influencing the response to exercise, but on the other hand, it may make the beta blocker less beneficial in minimizing the effects of myocardial ischemia. Beta blockers also differ in duration of action, vasodilating capacity and effect on renal blood flow. Several mechanisms may be involved in the antihypertensive effects of beta antagonists. In elderly hypertensive patients, beta blockade should be given cautiously, especially if combined with a diuretic, and pharmacokinetic differences in this age group must be considered.