Pfizer Canada Inc. and Pfizer Inc. v. Apotex Inc.

citation(s): (1997), 77 C.P.R. (3d) 547 (F.C.T.D. per Richard J.) online

JurisDictioncom.gif (2187 bytes)  Case Comment        2005 Donald M. Cameron, Ogilvy Renault



The patent at issue was a selection patent, claiming a compound encompassed within the broad claim of the prior art patent, but not specifically identified in it.

Different from the prior art, fluconazale:

The prior art patent:



This proceeding concerns the pharmaceutical fluconazole which is the invention of Dr. Kenneth Richardson of Sandwich, England, currently Director of Discovery Chemistry, Central Research Division, Pfizer Ltd.

The evidence on this application establishes that the fluconazole compound was a commercial success and has been widely used, in particular, because it is non-teratogenic.

The ICI Patent is an originating patent while the Pfizer Patent is a selection patent [Esso Research and Engineering Co.'s Application, [1960] R.P.C. 35 at p. 53.]. The former claims the genus; the second claims the species.  ICI's '263 Patent is directed generally to fungicidal triazoles and imidazoles.  Fluconazole is not specifically described and neither were its superior and previously unknown efficacy described or known. The ICI Patent did not include the fluconazole compound. ICI was not the first inventor of this compound and never made it.

It is not disputed that fluconazole is encompassed within the broad generic scope of the claims of the ICI Patent and likewise with respect to the processes, but is not specifically identified therein.

The ICI Patent discloses an enormous class of compounds. The compounds of the ICI Patent which are structurally closest to fluconazole are teratogenic, that is to say, they cause congenital deformities.

Dr. Kenneth Richardson's invention is a selection, from an enormous number of possibilities, of a compound, known as fluconazole, which has a high anti-fungal activity but does not have the undesirable side effect of the compound specifically disclosed by ICI, namely, the teratogenic side effect.

Dr. Richardson further explained that fluconazole has unobvious and advantageous therapeutic properties over the compounds specifically disclosed in the ICI Patent, namely, that in addition to being a potent anti-fungicide, fluconazole is not teratogenic.

It is soluble in water and thus can be used for parenteral (injection) administration. In contrast, the 2,4-dichloro derivative of the ICI Patent are teratogenic, and are virtually insoluble in water which would make them unsuitable for parenteral injection. The 4-fluorophenyl derivative is a significantly less potent antifungal agent than fluconazole.

None of the compounds disclosed in this patent are bis-triazole derivatives and this patent neither discloses nor suggests fluconazole or even a bis-triazole derivative. Accordingly, he [Dr. Richardson, the witness for Pfizer] concluded that it would not have been obvious from this patent, which pertains to a composition for seeds and plants comprising compounds having only one triazole component, to substitute the chlorine atoms in bis-triazole derivatives.

I find that fluconazole, the subject matter of the Pfizer Patent, has unexpected and valuable properties which are not possessed by the structurally closest compounds disclosed in the ICI Patent and the Finnish Patent application, to the extent it has been translated, including the fact that fluconazole is not teratogenic.

The Decision

The ICI United States Patent 4,205,075 (the ICI "075 Patent") neither discloses nor suggests fluconazole or even a bis-triazole derivative.

The respondents' allegation of invalidity because of anticipation and obviousness fails.


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