The Federal Court of Appeal has provided new guidance on the proper approach to the “patent pertaining” analysis used by the Patented Medicine Prices Review Board (PMPRB or Board), including on the identification of the medicine and the invention of the patent, in a case concerning Differin®. Having provided this guidance, the Court of Appeal set aside the judgment under appeal and remanded the final determination of whether or not the patent in question pertains to Differin® to the Board.


This case concerns Canadian Patent No. 2,478,237 (the 237 Patent), which relates to the use of adapalene to treat dermatological disorders. The patentee, Galderma Canada Inc. (Galderma), markets two adapalene products in Canada:

  • Differin®, which contains 0.1% adapalene.
  • Differin XPTM, which contains a higher concentration of adapalene — 0.3%.

As we reported, in an application before a hearing Panel of the PMPRB, the Board staff successfully argued that the 237 Patent pertained to Differin®. Galderma argued that the 237 Patent is not intended or capable of being used to make Differin® — a 0.1% adapalene formulation — because on its face, the patent is specific to 0.3% adapalene formulations (such as Differin XPTM). The Board Panel did not accept that argument.

Galderma sought judicial review of the Board’s decision and, as we reported, Galderma was successful before the Federal Court on the basis that the PMPRB had failed to consider the entirety of the 237 Patent when determining whether it pertained to Differin®.

The PMPRB must consider the whole patent

The first issue before the Court of Appeal was whether the Board acted unreasonably in limiting its review of the 237 Patent to selected portions of the patent.

The Court of Appeal held that the Board must read the patent as a whole — including the claims — in order to identify the invention. However, the Board is not required to construe the patent and the claims as a court would. The Board must arrive at a “reasonable” or “sufficient” understanding of the invention, but is entitled to take the patent “at face value” and is not required to arrive at the “correct” interpretation of the patent.

There was only one reasonable interpretation of the invention of the 237 Patent

The second issue before the Court of Appeal required determining the invention of the 237 Patent.

The Court of Appeal held that there was only one reasonable interpretation of the invention in the 237 Patent, and that the Court was entitled to supply that interpretation without returning the matter to the Board. Considering the patent as a whole, the Court of Appeal concluded that the invention of the 237 Patent is a pharmaceutical composition having a concentration of 0.3% adapalene to be used in the treatment of dermatological conditions with an inflammatory or proliferative component, such as common acne.

In the decision under review, the Board could not conclude that the 237 Patent pertains exclusively to 0.3% adapalene. The Court of Appeal held that the Board’s finding arose from an insufficient review of the 237 Patent. As a result, the Board’s finding was “erroneous and unreasonable”.

The Board must now determine if the invention of the 237 Patent pertains to Differin®

As a final step, the Court of Appeal considered whether the invention of the 237 Patent pertains to Differin.

  • Is the medicine “adapalene” or “Differin”? The Court of Appeal held that for the purpose of the patent-pertaining analysis, the “medicine” is the thing sold in Canada at the material time, i.e., Differin® (a 0.1% adapalene formulation) and not adapalene per se.
  • The “merest slender thread”?  The Court of Appeal held that when conducting the patent-pertaining analysis, the Board must be guided by the statutory definition of “pertains to” and cautioned against any strict substitution of “the merest slender thread” test for the words Parliament has chosen. The Court added that the metaphor may be useful to express the idea that the connection may be “tenuous” — provided it remains within the Act.
  • Does the invention of the 237 Patent pertain to Differin? Having provided the above guidance, the Court of Appeal returned the matter of whether the 237 Patent invention pertains to Differin® to the Board for redetermination. The Court of Appeal noted that:
    • (1) If the Board reached its decision solely on the basis that the patent did not relate exclusively to 0.3% adapalene, it was wrong and its decision should be quashed. The 237 Patent only relates to 0.3% adapalene.
    • (2) On the other hand, the Board referred to other factors that could have influenced its decision including evidence of similarities or differences between Differin® and Differin XPTM.

In the Court’s view the latter factors invoke policy considerations best decided by the Board. On that basis, the Court returned the matter to the Board to complete its inquiry with a proper understanding of the invention of the 237 Patent.

The case is Canada (Attorney General) v Galderma Canada Inc., 2019 FCA 196.