News Release

Yamanouchi Pharmaceutical Co., Ltd.

Yamanouchi Submits New Drug Application to the FDA for YM 087 to Treat Hyponatremia

February 2, 2004

Tokyo -February 2, 2004 - Yamanouchi Pharmaceutical Co., Ltd. ("Yamanouchi"; President and CEO: Toichi Takenaka) announced that its US subsidiary, Yamanouchi Pharma America (YPA: Paramus, New Jersey), has submitted a new drug application (NDA) to the US Food and Drug Administration (FDA) for YM 087 (generic name: conivaptan hydrochloride), an investigational drug to treat hyponatremia.

YM 087 is an injectable dual V1a/V2 vasopressin* receptor antagonist discovered by Yamanouchi. It has been reported to restore blood sodium levels in patients with euvolemic and hypervolemic hyponatremia by increasing excretion of free water without increasing the sodium output as a result of its vasopressin receptor antagonistic effect.

The total body fluid volume excessively increases relative to the total sodium amount in the body in hyponatremic patients. Major symptoms include personality change, somnolence, confusion, and other neurological symptoms. It is a common electrolyte disorder among inpatients. In the US, it is reported to occur in 1-6% of the roughly 30 million inpatients every year. Emergency care is recommended because severe hyponatremia may be life-threatening, but there is no effective drug at present. If approved, YM 087 will be the world's first drug to treat this condition.

Yamanouchi is constructing its own marketing system in the US. Vesicare to treat urinary frequency and urinary incontinence, which has been applied for to the FDA and which is expected to be launched within this year, is expected to be the first drug independently marketed by YPA. YPA plans to quickly launch YM 087 as the second product independently marketed by it in order to further consolidate its business base in the US market.

A peptide hormone consisting of 9 amino acids produced in the hypothalamus-neurohypophysis system. Called antidiuretic hormone, it increases free water retained in the body by reducing urinary output via V2 receptors in the kidneys. It is the only known factor which contributes to water reabsorption in the kidneys and is reported to be related to the pathology of hyponatremia. It also constricts blood vessels via vascular V1a receptors.