Tolvaptan, a Selective Oral Vasopressin V2-Receptor Antagonist, for Hyponatremia

Hyponatremia (serum sodium concentration, <135 mmol per liter) is a predictor of death among patients with chronic heart failure and cirrhosis. At present, therapy for acute and chronic hyponatremia is often ineffective and poorly tolerated. We investigated whether tolvaptan, an orally active vasopressin V2-receptor antagonist that promotes aquaresis — excretion of electrolyte-free water — might be of benefit in hyponatremia.