Tolvaptan is a vasopressin receptor antagonist. Vasopressin (a.k.a. ADH or antidiuretic hormone) helps to regulate water retention by absorbing water in the collecting ducts of the nephron.

clinical manifestations and outcome of the inappropriate secretion of antidiuretic hormone syndrome (SIADH). Serum sodium levels and osmolality of serum and urine were estimated on admission and ...