Esprolol hydrochloride: a new beta adrenergic antagonist with a rapid onset of effect.

Esprolol is a new, potent, beta adrenergic receptor antagonist that is differentiated from available drugs of this class by its rapid onset, short time to peak effect, and relatively short duration of action after sublingual and oral administration. The drug has potential for short-term use in patients with exertional angina and in patients with other diseases in which rapid-onset beta blocking action would be beneficial. The unique properties of esprolol are determined by the presence in its chemical structure of an ester group, which undergoes rapid metabolism by blood and tissue esterases to form an active metabolite, amoxolol. Preclinical testing and clinical trials in healthy volunteers have demonstrated the tolerability, pharmacokinetics, and beta adrenergic blocking properties of both esprolol and amoxolol. An ongoing trial to evaluate its usefulness in improving exercise performance in patients with exertional angina pectoris is nearing completion.