Pharmacology of 4-(2-hydroxy-3-[(1-methyl-3-phenylpropyl)-amino]propoxy)benzeneacetamide (KF-4317).

4-(2-Hydroxy-3-[(1-methyl-3-phenylpropyl)amino] propoxy)benzeneacetamide (KF-4317) differs from conventional adrenoceptor antagonists in producing a competitive blockade at both alpha- and beta 1-adrenoceptors. In blocking beta 1-adrenoceptors, KF-4317 is as active as labetalol in both in vitro and in vivo experiments, and 22 times less potent (in vitro) and 2 times less potent (in vivo) than propranolol. In blocking beta 2-adrenoceptors, KF-4317 is 776 times less potent (in vitro) and 83 times less potent (in vivo) than propranolol. The ratio of beta 1-blocking activity to beta 2-blocking activity is 33 to 145 for practolol, 37 for KF-4317, 1 for propranolol and 0.16 to 1 for labetalol, respectively. In blocking alpha-adrenoceptors, KF-4317 is 55 times less potent than phentolamine and 6 times less potent than labetalol in in vitro experiments, but as active as labetalol in in vivo experiments. These results show that KF-4317 possesses a novel type of adrenoceptor antagonistic property.