Adrenoceptor antagonists, also known as adrenoceptor blocking drugs, this drug can bind to adrenoceptors, but does not bind the receptor, mainly by preventing the activation of adrenergic agonists to play a role, the common clinical receptor antagonists are three, as follows: 1, alpha-receptor antagonists: alpha-receptor antagonists have long-acting and short-acting, short-acting common is phentolamine, long-acting is phenazopyridine, and is prazosin and yohimbine; 2, beta-receptor antagonists: common is propranolol, metoprolol and butazolamide; 3, mixed antagonists: is both alpha and beta receptor antagonism, called labetalol.