Abstract

A BRIEF REVIEW ON LABETALOL

K. Chandrika*, Dr. D. Rama Brahma Reddy and Dr. T. J. Mohan Rao

.

Abstract

Labetalol is an orally active adrenoceptor blocking is competitive antagonist at both alpha and beta adrenoceptor sites. Its beta blocking effects resemble those of propranolol, but its overall hemodynamic effects are akin to those of combination of propranolol and an alpha adrenoceptor blocking drugs such as phenoxybenzamine. Unlike with conventional beta adrenoceptor blocking drugs, acute administration of labetalol reduces peripheral vascular resistance and blood pressure and has little effect on cardiac output. Labetalol may be particularly useful in some patients whose blood pressure is not adequately controlled by beta adrenoceptor blocking drugs alone or combined with diuretics but possibly at the expense of postural hypotensive effect. Labetalol is more potent at beta that alpha1 adrenoceptors in man, the ratio of betaalpha antagonism is 3:1 after oral and 6:9:1 after intravenous administration. Labetalol is readily absorbed in man after oral administration, but the drug, which is lipid soluble, undergoes considerable hepatic first pass metabolism and has an absolute bioavailability of approximately 25%. Other reported side effects of the drug include gastrointestinal disturbances, tiredness, headache, scalp tingling, skin rashes, urinary retention. In this review, the pharmacokinetics, pharmacodynamics, pharmacological effects, mechanism of action, indications of labetalol were revisited. A comparison between labetalol and other drugs, contraindications in the usage of labetalol were also discussed.

Keywords: Labetalol, Alpha- adrenoceptor antagonist, Beta adrenoceptor antagonist, Hypertension, Pharmacology.