Tokyo-based Eisai Co Ltd and Abbott GmbH & Co., KG, formerly Knoll AG have signed a letter of agreement to amend the original co-development, licensing and supply agreement for KES524 (generic name: sibutramine) concluded in December 1997.

Under the amendment, Eisai shall have the exclusive right and sole responsibility for the continued development and marketing of the product in Japan. The companies signed the binding amendment letter on April 27. KES524, an obesity management, is central acting serotonin and noradrenaline reuptake inhibitor.

The principal change from the former agreement is that the development, marketing and promotion of KES524 will be performed solely by Eisai instead of co-development and co-marketing by Eisai and Abbott Japan, a Japanese subsidiary of Abbott Laboratories.

Eisai will promote the development of KES524 more actively in order to contribute the obesity management that is of increasing social concern in recent years in Japan.