ABSTRACT
The effect of a single oral dose of beta-1 blocker [Metoprolol] versus combined alpha- and beta-blocker [Labetalol] was evaluated in two groups of patients: Control [C] normotensive and hypertensive [H] groups with mild to moderate elevation of blood pressure. Each group consisted of 10 subjects. The study comprised monitoring the heart rate [HR] and blood pressure [BP] response to two tests: Hand grip test [HCT] and cold pressor test [CPT]. These tests were performed before and after the drugs on separate sittings. The BP and HR response to HGT before administration of drugs was linear for the two groups, while the CPT showed insignificant rise of HR. The results at rest before and after medications in both groups showed a decrease in HR and BP. It was statistically insignificant in C group only after Labetalol used. In C group Metoprolol was more effective in lowering the pressor response than Labetalol, while in the H group Labetalol was potent in reducing BP, specially during CPT
Subject(s)
Metoprolol/pharmacology , Labetalol/pharmacology , Exercise TestABSTRACT
En el presente estudio de diseño simple-ciego, placebo-control, cruzado y randomizado, evaluamos la respuesta tensional y las modificaciones hemodinámicas causadas por el tratamiento oral y durante dos semanas con un agente bloqueador beta-adrenérgico selectivo con efecto simpático-mimético intríseco (Acebutolol, 400 mg/día) o con un agente bloqueador alfa y beta-adrenérgico (Labetalol, 400 mg/día). A tal efecto, 25 pacientes hipertensos leves fueron sometidos a ejercicio isométrico al 30% de su capacidad máxima y a ejercicio dinámico hasta un máximo de 75W, bajo monitoreo con electrograma de impedancia y durante ciclos de tratamiento con placebo, Acebutolol o Labetalol en forma cruzada, La efectividad terapéutica de ambas drogas fue similar en reposo, pero el Labetalol indujo una menor respuesta hipertensiva al ejercicio isométrico que el Acebutolol, la cual parece deberse a un menor incremento de las resistencias periféricas. Durante el ejercicio dinámico se observó una atención de la respuesta hipertensiva similar con ambos medicamentos; el labetalol, sin embargo, permitió un incremento del gasto cardíaco mayor que el tratamiento con Acebutolol. Estos efectos diferenciales del Labetalol se atribuyen a su efecto bloqueador alfa-adrenérgico, y lo hacen particularmente útil en pacientes hipertensos con actividad física moderada o intensa
Subject(s)
Adult , Middle Aged , Humans , Male , Female , Acebutolol/pharmacology , Exercise/drug effects , Labetalol/pharmacologySubject(s)
Adult , Blood Pressure/drug effects , Cardiac Output/drug effects , Double-Blind Method , Ethanolamines/pharmacology , Humans , Isometric Contraction , Labetalol/pharmacology , Male , Muscle Contraction , Propranolol/pharmacology , Stress, Psychological/physiopathology , Vasoconstriction/drug effects , Vasodilation/drug effectsABSTRACT
Labetalol, an alpha- and beta- adrenoceptor antagonist was investigated for its central nervous system effects in rats and mice. A marked reduction in the spontaneous motor activity with no concomittant muscle weakness was produced. The drug caused closure of eyelids in rats. Labetalol caused hypothermia and prolonged the pentobarbitone-induced hyposis. In animals trained for conditioned avoidance response the drug blocked the SCR in all the animals and CAR in a few number of animals. The drug did not protect the animals against electroshock convulsions. From the results it appears that labetalol is a central nervous system depressant.