An ETA antagonist (Ki = 69 pM for the human receptor); selective for ETA over ETB (Ki = 139 nM for the human receptor) and a panel of 29 other receptors at 10 µM; inhibits endothelin-1-induced secretion of arachidonic acid from HPSMCs (pA2 = 10.5), as well as endothelin-1-induced vasoconstriction in isolated rat aortic rings (pA2 = 9.2); inhibits endothelin-1-induced increases in the pressor response in normotensive rats at 10 mg/kg; reduces urinary levels of albumin, TGF-β, and a PGE2 metabolite, as well as decreases the number of macrophages, in a rat model of streptozotocin-induced diabetic nephropathy at 5 mg/kg per day