Mozavaptan hydrochloride is primarily used in the treatment of hyponatremia, a condition characterized by low sodium levels in the blood. It works as a vasopressin receptor antagonist, helping to increase sodium levels by promoting the excretion of water without the loss of electrolytes. This makes it particularly effective in managing conditions like syndrome of inappropriate antidiuretic hormone secretion (SIADH). It is administered orally and is often prescribed when other treatments are not suitable or effective. Regular monitoring of sodium levels is essential during treatment to avoid overcorrection, which can lead to neurological complications.