Highly selective β1-adrenoceptor antagonist (Ki values are 0.88, 20, 44, 700, 1160, 2400 and 4000 nM at β1, 5-HT1A, β2, 5-HT2, α1, H1 and D2 receptors respectively). Induces vasodilation via a nitric oxide- and cGMP-dependent mechanism (EC50 = 11.36 μM in renal arteries) and displays antihypertensive activity in vivo. GRK/β -arrestin biased agonist at the β2 adrenoceptor. Purity 98%. MW (observed): 441.9