RESUMO
Hyponatremia is a common and often under-recogonised clinical problem in oncologic practice. The recogonition of the cause of hyponatremia and initiation of appropriate and timely intervention can prevent morbidity and improve treatment tolerance. This drug review aims at discussing the currently approved oral vaptanagent Tolvaptan. Vaptans including Tolvaptan act as "aquaretic" agents cousing excretion of water while retaining the sodium. Administration of this agent for prescribed periods result in improvement of serum sodium levels. The drug can be used in many clinical situations resulting in hyponatremia including congestive heart failure, cirrhosis and syndrome of inappropriate ADH secretion (SIADH) including SIADH related to malignancies.