Otsuka Pharmaceutical Co., Ltd.

Pharmaceuticals
December 10, 2010

World's First Aquaretic Agent for the Treatment of Volume Overload in Patients with Heart Failure Samsca® Tablets 15mg (tolvaptan), Vasopressin V2-Receptor Antagonist, to be Launched in Japan on December 14

Tokyo, Japan, December 10, 2010 -- Otsuka Pharmaceutical Co., Ltd. today announced that it will launch Samsca® Tablets 15mg (tolvaptan), a V2-vasopressin receptor antagonist, in Japan on December 14, 2010. Samsca is the world's first aquaretic treatment for volume overload in patients with heart failure, with a mechanism of action to increase free water excretion without an accompanying increase in electrolyte excretion.

Samsca is a nonpeptide vasopressin V2-receptor antagonist discovered by Otsuka Pharmaceutical, with a unique mechanism of action that selectively blocks the binding of vasopressin, an antidiuretic hormone, to the V2-receptors in the collecting duct of the kidney. The binding of vasopressin with the V2-receptors can cause water retention. By inhibiting vasopressin's effects at the V2-receptor, Samsca increases the excretion of free water and reduces the re-absorption of water from urine into the blood without directly affecting the excretion of sodium and other electrolytes. Samsca was granted approval on October 27, 2010, for the treatment of volume overload in heart failure when adequate response is not obtained with other diuretics (e.g., loop diuretics).

Fluid retention (edema) resulting from deterioration in heart pumping function can develop in individuals with congestive heart failure. Edema stemming from heart failure negatively affects patient quality of life by causing dyspnea and a decline in activity. While diuretics are generally used for the treatment of edema, there have been concerns reported about the insufficient effectiveness of conventional diuretics for some patients, and about serum electrolyte abnormalities and diminished renal function when diuretics are used in combination or in increased dosages.

"Diuretics have long been used for the treatment of water retention due to heart failure, to alleviate symptoms such as dyspnea," said Dr. Toru Izumi, Professor of Cardiovascular Internal Medicine, Kitasato University. "However, sufficient improvement is not always seen using existing diuretics alone. The use of diuretics in combination or in increased dosages may be considered in these cases, but this carries the risk of upsetting the electrolyte balance." "As an aquaretic agent that aids excretion of water without increasing excretion of electrolytes, Samsca Tablets are a completely new strategy and bring high expectations to the treatment of volume overload due to heart failure." added by Dr. Izumi.

Since the discovery of Samsca, Otsuka Pharmaceutical ,has conducted global development of the product in countries including North America, Europe, Japan and other parts of Asia for additional new indications. Samsca was first launched in the United States in June 2009 as that country's first oral selective vasopressin V2-receptor antagonist. It was subsequently launched in European countries including the UK and Germany following approval by the European Commission in August 2009. Samsca is the world's first aquaretic treatment for volume overload in patients with heart failure, with a mechanism of action that increases free water excretion without increasing electrolyte excretion.

Based on its corporate philosophy of 'Otsuka-people creating new products for better health worldwide,' Otsuka Pharmaceutical Co., Ltd. is dedicated to contributing to the health of people around the world.

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