Urapidil

Urapidil is a sympatholytic antihypertensive drug. It acts as an α₁-adrenoceptor antagonist and as an 5-HT_1A receptor agonist. Although an initial report suggested that urapidil was also an α₂-adrenoceptor agonist, this was not substantiated in later studies that demonstrated it was devoid of agonist actions in the dog saphenous vein and the guinea-pig ileum. Unlike some other α₁-adrenoceptor antagonists, urapidil does not elicit reflex tachycardia, and this may be related to its weak β₁-adrenoceptor antagonist activity, as well as its effect on cardiac vagal drive. Urapidil is currently not approved by the U.S. Food and Drug Administration, but it is available in Europe.