A. H. El-Debam
Department of Pharmacology, Faculty of Medicine, University of Garyounis, Benghazi, S.P.L.A .J.
Garyounis Medical Journal Vol. 4, No.2. July 1981:55-59
1. Labetalol differs from conventiorw.l adrenoceptors blocking drugs in producing competetive blockade of both alpha and beta-adrenoceptors.
2. Labetalol is 10—12 times less potent than phentolamine in blocking rabbit intestinal alpha-o4renoceptors.
3. Labetalol is 3—4 times more potent than proctolol in blocking rabbit cardiac beta-adrenoceptors.
4. Labetalol is a non-selective beta-blocker where it blocks cardiac beta-adrerioceptors and intestinal beta-adrenoceptors.
5. Labetalol is 5—7 times more potent in blocking cardiac beta-adrenoceptor than intestinal beta-adrenoceptors.
6. Labetalol is 6—8 times more potent in blocking cardiac beta-adrenoceptors than intestinal alpha-adrenoceptors.
7. In doses of 20 ug/mI and 30 ug/ml, labetalol causes complete depression of the myogenic contraction of intestinal smooth muscles.
8. The results show labetalol to possess a novel profile of activity.
Keywords: The Relative Alpha- and Beta-Blocking Activity of Labetalol