An α-AR antagonist; inhibits norepinephrine-induced contractions in rat vas deferens, guinea pig spleen, and rat aorta, regions that express high levels of α1A-AR, α1B-AR, and α1D-ARs, respectively (pA2s = 7.93, 7.13, and 8.26, respectively); inhibits histamine-, angiotensin II-, pentagastrin-, carbachol, and serotonin-induced contractions in guinea pig ileum in a dose-dependent manner; reverses pupil dilation induced by the combination of phenylephrine and tropicamide in rabbits