Eisai-Pfizer Smackdown Anticipated

A major conflict looms between Eisai and Pfizer over the marketing of Aricept (ie, donepezil), the number-one prescription medication for Alzheimer disease. Last week, the Japanese-based company informed Pfizer that it had a legal right to terminate their comarketing agreement, after Pfizer's anticipated aquisition of Wyeth, reported the WSJ. Not surprisingly, Pfizer bristled at the warning, especially given that Aricept generated $482 million in sales for the US company last year.

The comarketing agreement, which has been in place since 1994, currently allows Pfizer to copromote Aricept (which was discovered and developed by Eisai) in the United States and several other countries, according to news reports. Pfizer also claims that is has an exclusive license to sell Aricept in certain other countries.

Pfizer's $68-billion acquisition of Wyeth is expected to be completed by the end of this year. Eisai's justification for getting out of its comarketing agreement may have something to do with Wyeth's development of a competitive product. Wyeth (with Elan) is currently investigating bapineuzumab, an anti-amyloid monoclonal antibody. However, results from phase 2 and 3 clinical trials in AD have been less than exhilarating—something that Pfizer probably didn't bet on.

Aricept, a cholinesterase inhibitor, was approved by the FDA for the treatment of AD in 1996. The basic patent on Aricept will expire in November of 2010.