A potent and selective α1-AR antagonist; selective for α1-AR (Kis = 3.28, 0.68, and 1.09 for α1A-, α1B- and α1D-ARs, respectively) over α2-AR subtypes (Kis = 1,510, 7.71, and 78.2 nM for A2a-, A2b-, and A2c-ARs, respectively); decreases blood pressure in spontaneously hypertensive rats when administered at 0.1-30 mg/kg