Beta-receptor antagonism does not fully explain esmolol-induced hypotension.

Esmolol is an ultra-short-acting beta-blocker that is widely used to lower blood pressure in acute settings intraoperatively and in patients with hypertension. Other beta-blockers have not been used in this way because of the belief that beta-blockers do not acutely lower blood pressure. The purpose of this study was to determine if esmolol has a hypotensive effect that is greater than other beta-blockers at similar degrees of beta-blockade. Esmolol, metoprolol, and propranolol were administered intravenously at three doses chosen to produce comparable degrees of beta-blockade. In spite of achieving comparable beta-blockade, esmolol produced a greater reduction in blood pressure than the other beta-blockers, implying that the hypotensive effect of esmolol cannot be accounted for simply by beta-blockade. There was no evidence to support a direct vasodilatory action of esmolol, and esmolol did not lower plasma norepinephrine concentrations.