Carvedilol is a β-adrenergic-blocking drug with vasodilating properties. This vasodilation has been ascribed to α1-adrenergic blockade, but it has never been shown in the clinical setting. We addressed this issue by studying eight patients with mild essential hypertension who were given prazosin, 2 mg or carvedilol, 25 mg p.o. following a 2-week washout from previous treatment, according to a randomized double-blind, crossover experimental design. Before and 2 h after the administration of either prazosin or carvedilol, the patients were infused i.v. with increasing doses of phenylephrine (0.2-1.2 μg/kg/min) and isoproterenol (0.01-0.05 μg/kg/min). The patients were thereafter maintained on carvedilol 25 mg daily for 3 weeks, and the i.v. phenylephrine and isoproterenol infusions were repeated 2 h after the last tablet administration. The results showed that the single dose of carvedilol and prazosin lowered blood pressure (beat-to-beat finger pressure measurement) to a similar extent, but that heart rate was unaffected by prazosin and reduced by carvedilol. The tachycardic response to isoproterenol was abolished by carvedilol and unaffected by prazosin, whereas the pressor response to phenylephrine was reduced by carvedilol and virtually abolished by prazosin. The antihypertensive, β-blocking and α1-adrenergic-blocking effects of carvedilol were unchanged following prolonged administration of the drug. Thus, at a clinically effective dose, carvedilol not only has β- but also sizeable α1-blocking effects. These effects are preserved during prolonged administration of the drug. For a comparable antihypertensive action, however, the α1-blocking effect is less pronounced than that of an α1-blocker such as prazosin.

alpha-1-Blocking properties of carvedilol during acute and chronic administration / C. Giannattasio, B.M. Cattaneo, G. Seravalle, S. Carugo, A.A. Mangoni, G. Grassi, A. Zanchetti, G. Mancia. - In: JOURNAL OF CARDIOVASCULAR PHARMACOLOGY. - ISSN 0160-2446. - 19:1(1992), pp. S18-S22. ((Intervento presentato al 5. convegno Satellite symp on multiple action agents in cardiovascular therapy at the 5th meeting of the European soc of hypertension tenutosi a Milano nel 1991 [10.1097/00005344-199219001-00005].

alpha-1-Blocking properties of carvedilol during acute and chronic administration

S. Carugo;A. Zanchetti;
1992

Abstract

Carvedilol is a β-adrenergic-blocking drug with vasodilating properties. This vasodilation has been ascribed to α1-adrenergic blockade, but it has never been shown in the clinical setting. We addressed this issue by studying eight patients with mild essential hypertension who were given prazosin, 2 mg or carvedilol, 25 mg p.o. following a 2-week washout from previous treatment, according to a randomized double-blind, crossover experimental design. Before and 2 h after the administration of either prazosin or carvedilol, the patients were infused i.v. with increasing doses of phenylephrine (0.2-1.2 μg/kg/min) and isoproterenol (0.01-0.05 μg/kg/min). The patients were thereafter maintained on carvedilol 25 mg daily for 3 weeks, and the i.v. phenylephrine and isoproterenol infusions were repeated 2 h after the last tablet administration. The results showed that the single dose of carvedilol and prazosin lowered blood pressure (beat-to-beat finger pressure measurement) to a similar extent, but that heart rate was unaffected by prazosin and reduced by carvedilol. The tachycardic response to isoproterenol was abolished by carvedilol and unaffected by prazosin, whereas the pressor response to phenylephrine was reduced by carvedilol and virtually abolished by prazosin. The antihypertensive, β-blocking and α1-adrenergic-blocking effects of carvedilol were unchanged following prolonged administration of the drug. Thus, at a clinically effective dose, carvedilol not only has β- but also sizeable α1-blocking effects. These effects are preserved during prolonged administration of the drug. For a comparable antihypertensive action, however, the α1-blocking effect is less pronounced than that of an α1-blocker such as prazosin.
carvedilol; beta-adrenergic blocker; vasodilation; alpha-1-adrenergic blockade
Settore MED/11 - Malattie dell'Apparato Cardiovascolare
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/793433
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