Tolvaptan in hyponatraemia secondary to syndrome of inappropriate secretion of antidiuretic hormone: a guide to its use in the EU

Abstract

Tolvaptan (Samsca®) is an orally administered highly selective vasopressin V2 receptor antagonist that increases the clearance of electrolyte-free water, thereby correcting low serum sodium levels. The drug is approved in the EU for the treatment of adults with hyponatraemia secondary to syndrome of inappropriate secretion of antidiuretic hormone (SIADH). In hyponatraemic patients with SIADH, tolvaptan 15–60 mg once daily, as an adjunct to standard medical treatment, increased serum sodium levels significantly more than placebo at day 4 and 30 in a subgroup analysis of the SALT trials. Mean serum sodium levels reached the target of >135 mmol/L within about 3–4 days and remained at that level throughout treatment, including treatment periods of up to 4 years. Once-daily tolvaptan is generally well tolerated, with most common adverse events being related to the aquaretic action of the drug.