Japanese drug majors Dainippon Pharmaceutical Co and Eisai Co have entered into a licensing agreement for the former’s investigational diabetic neuropathy drug, AS-3201 (ranirestat).

Under the terms of the deal, financial details of which were not revealed, Tokyo-based Eisai gains the exclusive rights to develop, manufacture and market the agent worldwide excluding Japan, to which Osaka-headquartered Dainippon has retained the license. The companies will co-promote the agent in major territories.

AS-3201, which is currently in Phase III clinical trials in the USA and Canada and Phase II studies in Japan, is designed to alleviate the symptoms of diabetic neuropathy through suppressing the accumulation of sorbitol within cells. Around 40% of diabetics develop neuropathies, with symptoms including numbness and pain in the hands, arms, feet and legs, and dizziness and faintness due to postural hypotension.

The market potential for this indication is significant, with an estimated 3.6 million sufferers in the USA, 2.6 million in the five major European countries and 1.7 million in Japan. Eisai hopes that adding this new treatment to its product line-up in the neurology arena, one of its four main franchise therapeutic areas, will help bolster the firm’s already robust sales, which hit $4.5 billion in fiscal 2003/4.