Impact of beta 1 selectivity and intrinsic sympathomimetic activity on potential unwanted noncardiovascular effects of beta blockers.

Beta-adrenoceptor-blocking drugs are widely used as effective antihypertensive and antianginal agents, but treatment with these agents may be contraindicated in hypertensive patients in whom receptor blockade would interfere with noncardiovascular activities dependent on sympathetic drive. beta blockade impairs pulmonary function in asthmatic patients through antagonism of beta 2 bronchodilation. However, patients with chest problems may be treated effectively with beta 1-selective drugs, including acebutolol, atenolol and metoprolol. The metabolic response to hypoglycemia, which is mediated by beta-receptor stimulation, involves insulin release, gluconeogenesis, tachycardia and increased systolic pressure. Beta 1-selective drugs are preferred in patients who need to increase blood glucose levels because they do not interfere with glycogenolysis. Hypertension induced by pregnancy may be treated with a beta blocker with no apparent adverse effects on the fetus or neonate. Those possessing intrinsic sympathomimetic activity may be preferable.