Competitive β3-adrenoceptor antagonist that displays selectivity over β1 and β2 receptors (Ki values are 4.0, 204 and 390 nM for β3-, β2- and β1-adrenoceptors respectively). Inhibits cAMP accumulation in response to isoproterenol (IC50 = 6 nM). Reduces iNOS expression, attenuates nitric oxide-induced cell proliferation and induces apoptosis in a melanoma cell line. Purity 98%. MW (observed): 497.61