An α1-AR antagonist; selectively binds to α1-ARs (Kis = 0.2, 0.25, and 0.32 nM for the human recombinant α1A-, α1B-, and α1D-ARs, respectively), over α2-ARs (Kis = 340 and 3.7 nM in α2A-AR-expressing HT-29 cells and α2B-AR-expressing NG108 cells, respectively); binds to MT3 in hamster brain membranes (IC50 = 7.8 nM); inhibits peripheral and central postsynaptic α1-ARs (IC50s = 0.2 and 1.7 nM in isolated dog aorta and rat brain, respectively); decreases diastolic blood pressure in normal, renal hypertensive, and spontaneously hypertensive rats at 1 mg/kg; increases the number of entries and percentage of time spent in the open arms of the elevated plus maze in alcohol-consuming rats and also reduces alcohol intake and alcohol-seeking behavior in alcohol-preferring rats at 1.5 mg/kg