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Court proposes new date for assessing double patenting

In Eli Lilly Canada Inc v Apotex Inc, 2015 FC 875, Justice Gleason of the Federal Court prohibited the Minister of Health from issuing a Notice of Compliance to Apotex for its tadalafil product until the expiry of Canadian Patent No. 2,226,784.

The 784 Patent

The 784 Patent is directed to the use of tadalafil (and 3-methyl tadalafil) for the treatment of erectile dysfunction in male animals, including humans. The 784 Patent discloses the mechanism of action of these compounds, as well as the results of in vitro testing. It does not contain any in vivo testing data.

The 784 Patent was also at issue in Mylan Tadalafil where Justice de Montigny concluded that Mylan’s allegations of double patenting and inutility were not justified (see our previous post, here). The appeal of that decision is scheduled to be heard in December of this year.

Double Patenting

Apotex alleged that the 784 Patent was invalid for double patenting over Canadian Patent No. 2,181,377. Both the 784 Patent and 377 Patent disclose tadalafil and disclose in vitro testing, but, unlike the 784 Patent, the 377 Patent does not discuss erectile dysfunction in any way. Justice Gleason found no reason to deviate from Justice de Montigny’s construction of the 377 Patent. Because the 377 Patent does not extend to the use of tadalafil to treat erectile dysfunction, Justice Gleason held that Apotex’ allegation of same invention-type double patenting was unsubstantiated.

For obviousness-type double patenting, Justice Gleason also noted the lack of authority on the date at which the analysis is to be made. In Mylan Tadalafil, the Court held that the relevant date was the priority date of the earlier patent. In considering the relevant date, Justice Gleason considered two different types of obviousness-type double patenting:

[131] On one hand, a patentee could under-claim in its initial patent, divide the invention and seek to extend the monopoly period by filing a subsequent patent before the first one is published. In such circumstance, the relevant inquiry involves assessment of what was known at the point in time for assessing obviousness in respect of the first patent. This is what the defendant argued had occurred in the Whirlpool case as it asserted that the invention in the latest patent was obvious when the earlier patents were filed (which, under the regime then in force, was the date for undertaking the obviousness inquiry in respect of a patent).

[132] Conversely, a second type of impermissible evergreening concerns the addition of obvious amendments. This is akin to the “non-inventive bells and whistles” rationale exemplified in Farbwerke, above. Particularly in the context of pharmaceutical patents involving a new use for an existing compound or class of compounds, there could be a situation where the common general knowledge advances after the claim date of the first patent that would render the new use claimed in the second patent obvious as of the claim date in the second patent, resulting in the later patent being an impermissible evergreening through extension based on obvious amendments to the initial patent. In such circumstance, I believe a sound argument may be made for the selection of the priority date of the second patent as being the date in respect of which the assessment of obviousness-type double patenting should be undertaken.

[133] The present case falls into the second of the above two possible scenarios and thus I believe that a sound argument exists for the selection of July 14, 1995, the priority date of the 784 Patent, as the date in respect of which the obviousness-type double patenting analysis should be undertaken.

However, Justice Gleason did not reach a conclusion as to the proper date as both relevant dates yielded the same result. Apotex had conceded that the use of the compounds of the 784 Patent for the treatment of erectile dysfunction was not obvious at the priority date of the 377 Patent. As of the priority date of the 784 Patent, Justice Gleason held that this use was still not obvious, in part because concerns about the systemic effects of tadalafil use persisted.


Apotex alleged that 784 Patent claims hydrates of tadalafil but does not provide enough information to enable a skilled worker to prepare them. Justice Gleason rejected Apotex’ allegation, concluding that there was adequate disclosure regarding the formation of hydrates in the 784 Patent and that Apotex’ allegation was therefore not justified.

A copy of the decision can be found here.