Esmolol. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy.

Esmolol is a relatively cardioselective beta-adrenoceptor antagonist. Since esmolol is rapidly metabolised by blood-borne esterases, it has a very short half-life (about 9 mins) and a short duration of action. In this respect esmolol is unique amongst currently available beta-adrenoceptor antagonists, and it is anticipated that it will be particularly useful in critical care situations where administration by continuous intravenous infusion should permit a level of control over beta-adrenoceptor antagonism that has previously been unattainable. In perioperative settings, esmolol attenuates tachycardia induced by a variety of surgical stimuli such as endotracheal intubation, sternotomy and aortic dissection, suggesting a clinical use of the drug to prevent potentially serious complications in surgical patients with cardiovascular disease. Additionally, clinical studies have shown that titrated dosages of esmolol achieved therapeutic response rates of 66 to 79% in patients with supraventricular tachyarrhythmias, which favourably compared with response rates achieved with propranolol. In most of these patients esmolol produced a reduction in ventricular rate which was well maintained during infusion but disappeared within 30 minutes following esmolol withdrawal. Preliminary studies involving small numbers of patients have reported that esmolol exerts significant antihypertensive effects in patients with postoperative hypertension, and beneficial effects in patients with myocardial ischaemia and infarction, but support for these results is required from additional large, well-controlled studies. Esmolol has been generally well tolerated, and although hypotension has occurred in up to 44% of patients it resolved during or soon after the infusion of esmolol. Thus, esmolol is the first titratable beta-adrenoceptor antagonist able to be rapidly 'switched on' and 'off', a property that is expected to offer a major contribution to safety in critical care patients requiring beta-adrenoceptor antagonism for short durations.