Soupart A et al. (2006) Successful long-term treatment of hyponatremia in syndrome of inappropriate antidiuretic hormone secretion with satavaptan (SR121463B), an orally active nonpeptide vasopressin V2-receptor antagonist. Clin J Am Soc Nephrol 1: 1154–1160

A study by Soupart et al. has evaluated the use of satavaptan for correction of mild to moderate hyponatremia in patients with syndrome of inappropriate antidiuretic hormone secretion (SIADH). The authors conclude that satavaptan, an oral nonpeptide vasopressin V2-receptor antagonist, is a safe and efficacious treatment for hyponatremia in this patient group. They report this to be the first study of long-term use of an oral vasopressin V2-receptor antagonist in patients with SIADH.

In the first part of the investigation, 34 patients received daily placebo, 25 mg/day satavaptan, or 50 mg/day satavaptan in a double-blind manner for up to 5 days. Mean baseline serum sodium levels were similar in the three groups (∼126 mmol/l). At the end of the double-blind period, mean serum sodium levels were significantly higher in the two groups receiving satavaptan than in the placebo group (placebo 130 mmol/l; 25 mg dose 136 mmol/l, P = 0.011 vs placebo; 50 mg dose 140 mmol/l, P <0.0001 vs placebo). Responses >5 mmol/l, or to normal levels (135–145 mmol/l), were observed in 79% of the 25 mg satavaptan group (P = 0.006 vs placebo), 83% of the 50 mg satavaptan group (P = 0.005 vs placebo), and 13% of the placebo group.

The investigators subsequently monitored the long-term effects of dose-adjusted satavaptan treatment in the same group of patients with SIADH. Ten patients completed the 12-month open-label study period; no treatment-related adverse effects were observed, and the authors report that the drug produced continuing serum sodium level response.