Potent β3-adrenergic receptor partial agonist > 1000-fold selective over β1- and β2-adrenoceptors (EC50 values are 0.43, 580 and > 10000 nM for activation of cloned human β3-, β1- and β2-adrenoceptors respectively). Stimulates lipolysis in rhesus adipocytes in vitro (EC50 = 3.9 nM).