While a number of orally active non-peptide V(2) antagonists (Vaptans); notably, Tolvaptan, Lixivaptan and Satavaptan, are currently in Phase III clinical trials; to date, only the mixed << V(2) >>/V(1a), antagonist Conivaptan ([[ Vaprisol ]]), has been approved by the US FDA for clinical use (by i.v. administration), for the treatment of euvolemic and hypervolemic hyponatremia in hospitalized patients.