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Patent Law

: Patently Obvious

Viagra, Cialis, & Bayer: Board of Patent Appeals Affirms Rejection of Pfizer?s Broad Patent over ED Treatment

By Dennis Crouch, Esq.

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Ex parte Pfizer (BPAI 2010)

Pfizer's broadest patent covering its bestselling drug Viagra is in the midst of an ex parte reexamination. See Patent 6,469,012. The reexamination was separately requested by Lilly & ICOS (makers of Cialis) and Bayer (maker of Levitra). In addition, the PTO director (then James Rogan) independently ordered reexamination. These separate actions were all merged into one proceeding before the PTO. In parallel, Pfizer has sued Lilly & ICOS ? asserting that Cialis infringes the Viagra patent. See Pfizer Inc., et al. v. Lilly ICOS LLC et al, Civil Action No. 02-1561 (D. Del. Oct. 22, 2002). The litigation has been stayed pending reexamination since 2003.

The broad claim (that is said to cover both Levitra and Cialis) is claim 24:

24. A method of treating erectile dysfunction in a male human, comprising orally administering to a male human in need of such treatment an effective amount of a selective cGMP PDEv inhibitor, or a pharmaceutically acceptable salt thereof, of a pharmaceutical composition containing either entity.

During the reexamination, the examiner rejected Claim 24 as anticipated by each of five different references and also issued an obviousness-type double patenting rejection based on three other Pfizer patents. In a 56-page opinion, the BPAI rejected some of the examiner's reasoning, but affirmed the decision as a whole.

In particular, the Board agreed that prior art descriptions of oral administration of the herb Yin Yang Huo (AKA Horny Goat Weed) serve as anticipatory prior art:

It is undisputed that the herb is orally administered, that icariin is an active component of the herb and that icariin is a selective PDEv inhibitor. Thus, the issue is whether the Yin Yang Huo references describe oral administration of the selective PDEV inhibitor icariin in an amount effective to treat ED. . . .

Appellant argues that a single dosage of Yin Yang Huo fails to provide an amount of icariin sufficient to treat ED . . . However, the selective PDEv inhibitor of claim 24 is not required to have a minimum % inhibition. . . . or a maximum Ki or other enzyme kinetics inhibition value or other defined parameter that would exclude Yin Yang Huo from the claimed method. Moreover, Yin Yang Huo is not administered as a single daily dosage when treating ED. Yin expressly defines one course of treatment as comprising administering 2.5 grams Yin Yang Huo 3 times per day for 20 days (FF 51). Therefore, this rebuttal evidence is insufficient to establish by a preponderance of the evidence that the Yin Yang Huo references fail to disclose oral administration of icariin in an amount effective to treat ED, particularly in view of [the prior art's] disclosed successful treatment of 50 cases of impotence.

Examiner Rejection Affirmed.

Notes

Pfizer has the opportunity to request a re-hearing and may also appeal the BPAI decision to either the District Court (35 U.S.C. § 145) or to the Federal Circuit (35 U.S.C. § 141).
The re-examination file history is quite long and includes over seventy-three-thousand pages (this total does not include the USPTO patent-documents cited as prior art).

Full post as published by Patently Obvious on February 15, 2010 (boomark / email).