In a recent decision, the Supreme Court of Canada held that Pfizer’s patent relating to sildenafil, the effective compound in Viagra, did not meet the disclosure requirements of the Patent Act, R.S.C. 1985, c. P 4. The Court deemed the patent to be invalid because of Pfizer’s failure to comply with those requirements. As a result of the decision, other pharmaceutical companies, including the appellant Teva Canada Limited, will have an opportunity to begin selling generic versions of the drug in advance of the patent’s expiry date in 2014. The Court’s full decision can be found here.  Pfizer has just recently announced that it is reducing the cost of Viagra in order to remain competitive with generic offerings of the drug.

The central issue on appeal was whether or not Pfizer had complied with the disclosure requirements of the Patent Act. Pfizer’s patent application included seven different “cascading” claims relating to various combinations of compounds. Only claim 6 and claim 7 related to individual compounds, with claim 7 pertaining specifically to sildenafil. At the time the patent application was filed, Pfizer was aware that sildenafil was the only effective compound for the treatment of erectile dysfunction; however, the application did not disclose which compound was effective. The Court noted that further testing would have been required to determine which compound was effective.

Teva’s application was unsuccessful at both the Federal Court and the Federal Court of Appeal. Both of those Courts considered whether a single claim within an application that contains several claims can be considered in isolation for the purposes of preserving Pfizer’s patent over the single valid claim. The Federal Court held that the invalidity of claims 1 through 6, which were invalid on the basis that the compounds claimed were ineffective, did not affect the validity of claim 7 of Pfizer’s application.

Teva argued that the Federal Court and Federal Court of Appeal erred by limiting the disclosure analysis to the only effective claim, claim 7. The Supreme Court agreed with Teva on the basis that Pfizer had not complied with the disclosure requirements of the Patent Act (found within s. 27(3)). The requirements state that specification of an invention (which specification contained all claims for all seven compounds) must “set out clearly the various steps in a process, or the method of constructing, making, compounding or using a machine, manufacture or composition of matter, in such full, clear, concise and exact terms as to enable any person skilled in the art or science to which it pertains, or with which it is most closely connected, to make, construct, compound or use it”.

In determining that Pfizer had not complied with s. 27(3), the Court followed the reasoning from Pioneer Hi-Bred Ltd. v. Canada (Commissioner of Patents), [1989] 1 S.C.R. 1623, at p. 1636. In that decision, the Court stated that: “(t)he description must be such as to enable a person skilled in the art or the field of the invention to produce it using only the instructions contained in the disclosure”. The Court found that Pfizer had not complied with this requirement, as it was not clear which of the claimed compounds was effective for the treatment of erectile dysfunction. A skilled person would not have been able to determine which compound was effective without further testing. The lower Courts erred by limiting their consideration of the disclosure requirements to each of the individual compounds rather than to the specification as a whole.

The case notes that Teva had been able to reproduce the drug, albeit with additional testing of the claimed compounds to determine which was effective. Pfizer argued that disclosure requirements had been met because of Teva’s ability to reproduce the drug. However, the need for additional testing simply served to confirm that Pfizer’s disclosure did not comply with the requirements of the Patent Act.

The  Supreme Court observed that “(t)he patent system is based on a “bargain”, or quid pro quo: the inventor is granted exclusive rights in a new and useful invention for a limited period in exchange for disclosure of the invention so that society can benefit from this knowledge.”  The Court’s decision is consistent with this principle, and serves to clarify that full disclosure is required for parties to enjoy monopoly rights over their inventions. The decision limits a party’s ability to enjoy those monopoly rights if they attempt to conceal their invention. Parties who attempt to “game” the system by concealing an invention will risk losing their exclusive rights to the invention on the basis that full disclosure has not been made.