Pfizer and Eisai have avoided a legal tiff and restructured a deal which will see the US-based drugs behemoth continue to co-promote the Japanese firm’s Alzheimer's disease blockbuster Aricept.

The companies say that they will still market Aricept (donepezil) together in the USA and key markets in Europe, while Pfizer will have exclusive rights to the drug in other countries. Specifically, the New York-headquartered firm will maintain its rights in territories where it currently commercialises Aricept until July 2022, with the exception of Japan, where it will return the rights to Eisai on December 31, 2012.

The firms have also signed a new deal which will see Eisai granted co-promotion rights to the neuropathic pain drug Lyrica (pregabalin) in Japan. Lyrica is under regulatory review there (it is already approved in the USA and Europe) and the agreement will continue until July 2022 as well.

Eisai said that the new collaboration with Pfizer should have a positive impact on its revenue and earnings after fiscal year 2010. The Tokyo-based group added that the deal follows discussions between the firms to resolve their dispute concerning the strategic alliance and development agreement signed in October 1994.

This summer, Eisai’s chief executive Haruo Naito told PharmaTimes World News that his company had “asserted its legal rights to terminate the contracts with Pfizer” once the latter’s merger with Wyeth is concluded. However he added that discussions were taking place and this morning’s announcement confirms the success of those talks.