Tolvaptan, sold under the brand name Samsca among others, is an aquaretic drug that functions as a selective, competitive vasopressin receptor 2 (V2) antagonist used to treat hyponatremia (low blood sodium levels) associated with congestive heart failure, cirrhosis, and the syndrome of inappropriate antidiuretic hormone (SIADH).

Tolvaptan was approved by the U.S. Food and Drug Administration (FDA) on May 19, 2009, and is sold by Otsuka Pharmaceutical Co. under the trade name Samsca.

[11] The U.S. Food and Drug Administration (FDA) granted tolvaptan a fast track designation for clinical trials investigating its use for the treatment of polycystic kidney disease.

[12] The FDA granted Jynarque an orphan drug designation in April 2012, for the treatment of autosomal dominant polycystic kidney disease.

[16] Tolvaptan (Jynarque) is indicated for slow kidney-function decline in adults at risk of rapidly progressing autosomal dominant polycystic kidney disease (ADPKD).