Otsuka Pharmaceutical Co., Ltd. (Otsuka; Head Office: Chiyoda-ku, Tokyo; President: Tatsuo Higuchi; Tel: +81-3-3292-0021) received approval in Japan on January 23, 2006, for its atypical antipsychotic Abilify^® (code name: OPC-14597; generic name: aripiprazole).

Abilify^® has been under development by Otsuka ever since it was discovered by the company in 1988. In November 2002, Otsuka received approval for Abilify^® in the US as a drug for the treatment of schizophrenia, and sales of Abilify^® in the US reached approximately 130 billion yen in 2005. Abilify^® has also been successively launched in Europe and a total of more than 40 countries worldwide, with 2005 global sales surpassing 150 billion yen. Outside of Japan, other Asian countries, and Egypt, Abilify^® is jointly marketed by Otsuka and Bristol-Myers Squibb (BMS)^*.

• *Otsuka (including local corporations) has exclusive marketing rights for Abilify^® in Japan, China, Taiwan, South Korea, the Philippines, Thailand, Indonesia, Pakistan, and Egypt, with the drug currently being marketed in South Korea, Indonesia, Taiwan, Thailand, Egypt, and the Philippines. Otsuka has the approval and marketing rights in the US and EU countries. In the US and four EU countries (UK, France, Germany, and Spain), Abilify^® is jointly marketed by Otsuka local corporations and BMS, and in other countries it is marketed by BMS.

Abilify^® is thought to work as a partial agonist against the dopamine D₂ receptor. In this regard, this therapeutic agent for schizophrenia possesses a novel mechanism of action unlike that of any other antipsychotic drug. Abilify^® exerts an inhibitory action when large amounts of dopamine are released in the brain and a stimulatory action when dopamine is released in small amounts. In view of this mechanism of action, Abilify^® is described as a dopamine system stabilizer (DSS) that stabilizes the dopamine system, enabling the drug to improve both the positive and negative symptoms of schizophrenia which are considered to be induced by dopamine abnormalities. At the same time, Abilify^® is unlikely to cause any of the untoward reactions that stem from excessive inhibition of dopamine, nor other unfavorable reactions such as drowsiness and weight gain. Abilify^® is therefore considered to be suitable for long-term use in the treatment of schizophrenia.

Schizophrenia is the most chronic and debilitating of the various psychiatric disorders. The lifetime prevalence of schizophrenia is said to be approximately 1% of the population worldwide. Schizophrenia interferes with a person's social ability to think clearly, manage emotions, make decisions, and relate to others. The disease often develops in early adulthood and is characterized not only by positive symptoms such as hallucinations and delusions but also by negative symptoms such as lack of emotional expression, lack of communication with others, and lack of motivation.

Otsuka is dedicated to contributing to the health of people around the world under its corporate philosophy of "Otsuka - people creating new products for better health worldwide."

Summary of Abilify^®