An orally-bioavailable, non-selective β-AR antagonist (Ki = 7.10 nM in rat heart tissue); inhibits both β1- and β2-ARs (Kds = 2.09 and 1.35 nM, respectively, in isolated rat heart and uterus); selective for β-ARs over 5-HT receptors in rat sarcolemmal membrane preparations (IC50s = 4.13 and 23,300 nM, respectively); binds to 5-HT1A and 5-HT1B (Kis = 94.2 and 642 nM, respectively, in rat brain); exhibits some intrinsic sympathomimetic activity