Potent and selective competitive vasopressin V2 receptor antagonist (Ki values are 0.06 and 12.3 nM for V2 and V1a receptors respectively). Decreases urine osmolality and increases serum sodium concentrations. Delays the onset of end-stage renal disease in a mouse model of polycystic kidney disease. Exhibits myocardial and renal protective effects in hypertensive heart failure rats. Orally active. Purity 98%. MW (observed): 448.94