Broad Anticipation in the Case of the Horny Goat Weed

Alex Gloor is a JD candidate at Osgoode Hall Law School and is taking the Patent Law course.

The world of patent law has certainly been excited since the Febuary 12th decision of Ex Parte Pfizer made by a U.S. Patent and Trademark Office panel. In this case, the broadest claim within Pfizer’s 2002 “Viagra patent” was rejected as being anticipated and also because it violated the obviousness-type double-patenting doctrine. It was found that claim 24 of the Viagra patent failed the 35 U.S.C. §102(b) anticipation requirement because of some dubious references in scientific literature to the use of the herb Yin Yang Huo, also known as “horny goat weed”.

Claim 24 of the Viagra patent reads:

“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.”

This case can be analyzed from numerous angles. There is obviously the obviousness perspective. Additionally, it is easy to bemoan the length of the proceeding, which may be appealed and is actually a reexamination that began in 2003, stemming from a 2002 action by Pfizer against Eli Lilly regarding Cialis. Finally, from a Canadian perspective, it could be discussed whether the claim would have been valid in the first place given exclusion to patentability for methods of medical treatment. However, to avoid an overly convoluted post, this discussion will be limited to the Court’s finding regarding anticipation.

The questionable part of the decision was Court’s unquestioning acceptance of a method of treatment described in a scientific paper as proof of Yin Yang Huo’s efficacy. In this paper, the typical test subject was an impotent 27 year-old male. During treatment, they were told to remain abstinent for 100 days, avoid excessive heat or cold and to massage the lower abdomen and perineum 10 times for one minute each three times a day. In addition, they ingested five grams of horny goat weed three times per day for twenty-day cycles. This treatment was shown to have cured 50 young males after an average of 48.5 days of treatment. It was held that because Yin Yang Huo was taken in a cumulative manner, and because of the successful treatments, the fact that Pfizer scientists showed that horny goat weed was a poor stimulant when taken in single dosages (in fact, it is 150 times less potent than Viagra) was insufficient to establish “by a preponderance of the evidence” that the goat weed failed to treat ED.

This seems like bogus reasoning to me. Never mind that Pfizer may not have shown that the horny goat weed did not treat impotence. I fail to see how, on a preponderance of the evidence and given a presumption of novelty, the scientific reference in question affirms horny goat weed’s effectiveness as a treatment. Fifty people is a small sample size. Further, when those fifty people are young males who are instructed to receive three daily genital massages while remaining abstinent for the duration of the treatment, should flags not be raised about horny goat weed’s effectiveness on its own? As pointed out, the PTO would require much more persuasive and stringent tests to be conducted before granting legal protection for the research.

This is a case where Pfizer wrote their own death, so to speak, by making such an all-encompassing claim. And while I may not be thrilled with the reasoning used to invalidate claim 24, that claim 24 was allowed in the first place does strike a nerve. By discovering that sildenafil citrate acts as an effective cGMP PDEv inhibitor, and thus is an effective treatment for ED, Pfizer is unquestionably deserving of protection. This is covered by other claims in the Viagra patent, which are all still valid. But allowing them a broad claim covering all cGMP PDEv inhibitors used for treating impotence is contrary to policy underlying the patent system in the first place. Patents are meant to encourage research and development through the disclosure of ideas and the incentive of protection. However, such broad claims that fence in an entire method of treatment serve as a deterrent to future inventors. By allowing claims such as the one at issue, the USPTO basically allowed the patenting of an idea of how to treat impotence, rather than limiting the claim to the practical application of the idea itself.

Finally, it is interesting to consider whether claim 24 would have been rejected under the Canadian doctrine of anticipation. Anticipation in Canada is guided by the two-step Beloit test, as clarified in Sanofi-Synthelabo v. Apotex. This test requires both disclosure, in accordance with the current s. 28.2 of the Patent Act, and enablement, based on a four-factor test outlined in paragraph 37 of Sanofi-Synthelabo.

The first prong, disclosure, seems to be met. The horny goat weed paper outlines the “special advantages” of administering Yin Yang Huo by the means described. Enablement, however, may prove to be a stumbling block. Enablement requires a reading of the prior art as a whole. It also allows a person skilled in the art, in this case a researcher in the field, to use common or general knowledge to supplement the prior claim. Finally, while errors in the prior art do not prevent enablement, they are free to be “readily corrected”. Reading the horny goat weed papers as a whole, supplemented by common sense of those skilled in the art, it may be shown that the horny goat weed was not in fact the reason for the miraculous impotence cures. While Pfizer’s evidence of the extremely low efficacy of the horny goat weed as a cGMP PDEv inhibitor may not have been enough to show an error in the prior art, the four-factor enablement test outlined by Rothstein J., along with a presumption of novelty, would certainly provide adequate room for a finding upholding the patent. The question is whether they would choose to do so, given the ambitious and questionably over-reaching nature of Pfizer’s claim.