Eisai is looking to file a new formulation of Aricept in the next couple of months and is confident about terminating its collaboration with Pfizer, the Japanese drugmaker’s marketing partner for the Alzheimer's disease blockbuster.

The Tokyo-based group has completed a late-stage study of Aricept (donepezil) 23mg sustained-release in patients with moderate to severe Alzheimer's disease. The Phase III trial was designed to increase “clinical benefits while maintaining a favourable safety profile” compared to the currently-marketed Aricept 10mg immediate-release form, Eisai said, and based on preliminary data, it plans to submit a New Drug Application with the US Food and Drug Administration in August or September.

Additinally, in February, Eisai filed an application proposing a design for paediatric studies with the FDA to evaluate donepezil in children with attention impairment following cancer treatment. The agency said there were insufficient grounds to grant paediatric exclusivity, so Eisai plans to complete ongoing studies “to provide important information on this therapeutic approach for an underserved patient population”.

Thirdly, Eisai noted that clinical trials of a once-a-week transdermal Aricept patch are currently being conducted by partner Teikoku Pharma USA (a unit of Teikoku Seiyaku) and an NDA submission is planned for the middle of fiscal year 2009. The importance of Aricept to the Japanese firm is considerable as it makes up around 40% of its overall sales. However the drug goes off-patent in the USA in November 2010 and Eisai is hoping these new formulations will help combat any generic competition.

Eisai will also be hoping to get virtually all the revenues from these formulations as it looks to cut ties with Pfizer, its Aricept marketing partner since 1994. Chief executive Haruo Naito, talking to PharmaTimes World News at the opening of Eisai’s £100 million European headquarters in the UK last week, said that the firm “has asserted its legal rights to terminate the contracts with Pfizer” once the latter’s merger with Wyeth is concluded.

“Pfizer of course disagrees,” Mr Naito said, but noted that the firms are “engaged in discussions to find a solution”, while remaining “committed to Alzheimer’s patients and their families”. The New York-based drug major banked $482 million in sales of Aricept last year and the copromotion deal covers the USA and several other countries.