Used primarily in the treatment of hyponatremia (low sodium levels in the blood), especially in patients with heart failure, liver cirrhosis, or syndrome of inappropriate antidiuretic hormone secretion (SIADH). It works by blocking the action of vasopressin in the kidneys, promoting the excretion of free water without significant electrolyte loss. This selective V2 receptor antagonism helps increase serum sodium concentration. Also indicated for slowing kidney cyst growth and decline in kidney function in adults with autosomal dominant polycystic kidney disease (ADPKD). Its aquaretic effect makes it valuable in managing fluid overload without causing substantial diuresis of electrolytes.