Successful Long-Term Treatment of Hyponatremia in Syndrome of Inappropriate Antidiuretic Hormone Secretion with Satavaptan (SR121463B), an Orally Active Nonpeptide Vasopressin V2-Receptor Antagonist

The effects of satavaptan (SR121463B), a novel long-acting orally active vasopressin V(2)-receptor antagonist, were investigated in patients with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). In the first part of this randomized, double-blind study, 34 patients first were treated with satavaptan (versus placebo) for up to 5 d and then during 23 d of open-label dosage-adjustment period. In the second part of the study, long-term efficacy and safety of satavaptan was assessed in an open-label trial during at least 12 mo. Mean (+/-SD) serum sodium (SNa) levels before treatment were 127 +/- 2 mmol/L (placebo, n = 8), 125 +/- 6 mmol/L (25 mg, n = 14), and 127 +/- 5 mmol/L (50 mg, n = 12). Responders (patients SNa levels normalized or increased by at least 5 mmol/L from baseline during the double-blind period) were 79% in the 25-mg group (SNa 136 +/- 3 mmol/L; P = 0.006), 83% in the 50-mg group (SNa 140 +/- 6 mmol/L; P = 0.005), and 13% in the placebo group (SNa 130 +/- 5 mmol/L). No drug-related serious adverse events were recorded. During the long-term treatment, 15 of 18 enrolled patients achieved 6 mo and 10 achieved 12 mo of treatment. The SNa response was maintained during this time with a good tolerance. The new oral vasopressin V(2)-receptor antagonist satavaptan adequately corrects mild or moderate hyponatremia in patients with SIADH and has a good safety profile.