Replies to post #94814 on Biotech Values

[DewDiligence]

Eisai’s ‘841 patent did not block the FDA from granting final approval for the Aricept ANDA’s because Eisai added the ‘841 patent to the Orange Book too late. From the FDA’s final-approval letter to Mutual Pharma:

As noted in the agency's publication titled Approved Drug Products with Therapeutic Equivalence Evaluations (the "Orange Book"), U.S. Patent No. 4,895,841 (the '841 patent) is scheduled to expire on November 25, 2010. With respect to the '841 patent, FDA has determined that information on this patent was submitted to FDA by the NDA holder (a) after the date of the submission of your ANDA, and (b) more than 30 days after the patent was issued by the u.s. Patent and Trademark Office. Therefore, under 21 CFR 314.94(a) (12) (vi), no person with an appropriate patent certification at the time of the submission of the patents was required to submit an amended patent certification to address the '841 patent.

p.s. You’re correct that Aricept no longer has Hatch-Waxman exclusivity—it expired in Oct 2009.