Astellas’ Vaprisol Approved For “Water Poisoning” Indication
This article was originally published in The Pink Sheet Daily
Executive Summary
Arginine vasopressin antagonist is the first drug indicated for the treatment of euvolemic hyponatremia.
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FDA approved Astellas Pharma's Vaprisol (conivaptan) Dec. 29 for the intravenous treatment of hospitalized patients with euvolemic hyponatremia, a life-threatening condition that occurs when the body's blood sodium levels fall significantly below normal. The arginine vasopressin antagonist is the first drug specifically indicated to treat this condition, Astellas said. FDA also issued an "approvable" letter for Vaprisol for the related indication of treatment of hypervolemic hyponatremia. Astellas said it "plans on working closely with the FDA to obtain an approval" for the additional indication. Labeling for Vaprisol says it is "not indicated for the treatment of patients with congestive heart failure" and includes a Precaution stating that "the safety of Vaprisol in hyponatremic patients with underlying congestive heart failure has not been established." A Phase II trial evaluating Vaprisol's ability to restore blood sodium levels in acutely decompensated chronic heart failure patients is underway (1 (Also see "Yamanouchi's Vaprisol Goes To Advisory Committee Sept. 9 As First Hyponatremia Drug" - Pink Sheet, 16 Jul, 2004.)). Hyponatremia is a condition that affects up to 4% of hospital patients in the U.S. each year, the company said. The approval was based on a double-blind, placebo-controlled, randomized study of 56 patients with euvolemic hyponatremia, who were treated for four days with Vaprisol or placebo. After treatment with 40 mg/d of Vaprisol over two and four days, 39% and 67% of patients, respectively, achieved normal serum sodium concentrations. Infusion site reactions are included in labeling as the most common type of adverse event leading to discontinuation of Vaprisol. The NDA for Vaprisol was submitted by the Japanese drug maker Yamanouchi in January 2004. However, Tokyo-based Astellas was established April 1 from the merger of Yamanouchi and Fujisawa. Other hyponatremia therapies are in late-stage development. Sanofi-Aventis has a vasopressin receptor antagonist aquaretic in Phase III for hyponatremia and Otsuka's tolvaptan (OPC-41061) vasopressin V2 receptor antagonist is in Phase III trials for hyponatremia and congestive heart failure. -Bowman Cox |