Celiprolol: a new beta adrenoceptor antagonist with novel ancillary properties.

Celiprolol HC1 is a new cardioselective beta-blocker with properties which may make it the next advance in the evolution of this class of compounds. Its cardioselectivity has been demonstrated both in vitro and in vivo, with an intravenous potency equivalent to atenolol. The compound is devoid of a membrane stabilizing effect which is reflected in anesthetized dogs by a lack of myocardial electrophysiological effects. The compound induces a vasodilator effect in anesthetized dogs which is partially attenuated by propranolol, suggesting a weak beta 2-agonist activity. This beta 2-agonist property is also manifested in other peripheral tissues and undergoes down-regulation with repeat exposure. In contrast to other beta-blockers, celiprolol produces a bronchodilation in anesthetized cats which is propranolol-resistant. Isolated tissue studies suggest that a weak alpha 2-blocking effect contributes to this bronchodilation, although another unknown mechanism participates as well. Celiprolol induces a cardiac stimulation in anesthetized dogs which is inhibited by propranolol. The mechanism for this effect appears to be due to adrenergic interaction. These unique properties of celiprolol convey salutary effects in the clinical use of celiprolol.