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Board of Patent Appeals affirms rejection of Pfizer’s broadest patent claim to Viagra
By Abby Lauer – Edited by Frank Sabatini

Ex parte Pfizer, Inc., Appeal 2009-004106 (B.P.A.I. Feb. 12, 2010).
Slip Opinion

On February 12, the Board of Patent Appeals and Interferences affirmed a Patent Examiner’s rejection of claim 24 of Pfizer’s patent on the erectile dysfunction (ED) drug Viagra.

The Board held that claim 24 of the patent was anticipated in the prior art by descriptions of the herb Yin Yang Huo (Horny Goat Weed). In addition, the Board invalidated the claim based on the judicially created doctrine of obviousness-type double patenting, a doctrine that seeks to prevent unjustified extension of the right to exclude that is limited by the twenty-year patent term. In holding as it did, the Board rejected some of the Examiner’s reasoning but agreed with his ultimate decision to invalidate the claim.

PatentlyO provides an overview of the case. BusinessWeek discusses the impact of the decision on Pfizer and its competitors Eli Lilly & Co. and Bayer AG, the makers of ED drugs Cialis and Levitra respectively.

Yin Yang Huo, also known as Horny Goat Weed, is a Chinese herb that is known to have medicinal properties. In its opinion, the Board cited four references that demonstrate the successful treatment of ED by oral administration of the herb. Ex parte Pfizer, Inc., Appeal 2009-004106 at 30 (B.P.A.I. Feb. 12, 2010). Because a specific ingredient in the herb effectively treats ED in the same way described by Pfizer in claim 24, the Board agreed with the Examiner that the claim was anticipated in the prior art and is therefore invalid. Id.

The Board also rejected claim 24 on the grounds that it is an obvious duplicate of two previously patented claims issued to a researcher named Campbell in 2000. Id. at 54. These previously patented claims “each recite a method of treating male ED by generally administering a defined species of [nucleotide] inhibitor.” Id. at 30. Pfizer’s claim 24 describes the treatment of “male ED by oral administration of any . . . [such] inhibitor.” Id. The Board affirmed the Examiner’s finding that claim 24 is an obvious duplication of Campbell’s patents because it is clear that a person “of ordinary skill in the art” could have predicted that oral administration of the compounds described in two out of three of Campbell’s claims would effectively treat ED. Id. at 52-54.

Claim 24 is the broadest of Pfizer’s patent claims to Viagra and covers competing ED drugs Cialis and Levitra. Id. at 4. A 2002 patent infringement suit brought by Pfizer against Eli Lilly & Co., the makers of Cialis, has been stayed since 2003 pending reexamination of claim 24. Pfizer has the right to appeal the Board’s decision to the Federal Circuit, but, if the rejection stands, it will severely weaken Pfizer’s infringement claims against Eli Lilly & Co. The other claims of Pfizer’s Viagra patent, however, will still allow the company to collect licensing fees from generic drug manufacturers that want to make ED drugs with sildenafil citrate, the active ingredient in Viagra (BusinessWeek).

Posted On Feb - 24 - 2010 Comments Off

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