Pfizer v. Novopharm; 55.2 decision; 2009 FC 638; sildenafil; June 18, 2009

The Federal Court granted prohibition in respect of a patent claiming the use of sildenafil for the treatment of erectile dysfunction by oral administration.

The patent had previously been challenged by another generic company, with an allegation that the patent was invalid for obviousness, anticipation and failure to meet the requirements of the legislation. The Trial Division in that previous case granted prohibition, which was upheld by the Court of Appeal.

In this case, Novopharm also alleged the patent was invalid for obviousness. The Court considered Novopharm's evidence and found that Justice Mosley's previous conclusions on obviousness were comprehensive and that the Novopharm allegation was unjustified.

The Court found the allegation of inutility to be not justified, holding that there is no requirement in patent law that evidence of utility must be included in the patent. It is sufficient that the patent states that the invention has been demonstrated to be useful and that the patent holder can show evidence of demonstrated utility if validity is challenged. Further, a study demonstrating utility does not need to meet the standards required for regulatory approval. The Court did not consider sound prediction on the basis that utility had been demonstrated.

The Court also refused to invalidate the whole patent on the basis of inoperability of certain compounds. It applied s.58 of the Patent Act and found that inoperative species do not affect the validity of other claims where the compound works as promised.

The Court also found the allegation of insufficiency not to be justified, holding that an insufficiency attack will only succeed where a person skilled in the art could not put the invention into practice. The patent contained a statement that one of the especially preferred compounds induced penile erection in impotent males. However, this compound was not explicitly identified in the patent. There were only 9 compounds in the list of those especially preferred.

Furthermore, the importance and value of the patent should not be invalidated by such an objection 13 years after the patent was laid open for public inspection. The credibility of the sufficiency allegation was undermined by its timing. The Court accepted expert evidence that the skilled reader would know that one of the two single compounds claimed in claim 6 or 7 were one of those compounds that worked. Thus, the allegation based on insufficiency is unjustified. However, the Court made a number of obiter statements inviting the Court of Appeal to comment on this reasoning.

The full text of the decision can be found at: