The Patented Medicine Prices Review Board (PMPRB or Board) has found that a patent can pertain to a medicine based on clinical similarities to the invention—even if the patent does not actually encompass the medicine.


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).
  • Differin XPTM, which contains a higher concentration of adapalene: 0.3% (DIFFERIN XP).

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 for DIFFERIN—a 0.1% adapalene formulation—because on its face, the patent is specific to 0.3% adapalene formulations (such as DIFFERIN XP). The Panel did not accept Galderma’s argument.

Galderma sought judicial review of the Board’s decision. 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.

Board Staff appealed the Federal Court’s decision and, as we reported, the Federal Court of Appeal (FCA) found that the PMPRB’s patent-pertaining analysis was unreasonable. The FCA returned the matter to the PMPRB for redetermination on the basis that the invention of the 237 Patent is the use of a 0.3% concentration of adapalene for the treatment of dermatological disorders. The FCA held that the PMPRB should be allowed to address “what kind of clinical similarities would support a finding that the invention of a patent was intended or capable of being used” for a specific medicine.

Board redetermination: A patent need not encompass a medicine to pertain to it

The PMPRB rejected Galderma’s argument that the 237 Patent does not pertain to DIFFERIN because it does not encompass DIFFERIN. The Panel found that “if the appropriate test was that the invention must encompass the medicine at issue, the Federal Court of Appeal would not have directed the Board to consider what ‘kind of clinical similarities would support a finding that the invention of a patent was intended or capable of being used for that medicine’.”

Clinical similarities used to ground patent-pertaining analysis

Since the 237 Patent reflects DIFFERIN XP, the Board compared DIFFERIN XP to DIFFERIN to assess the clinical similarities and differences between the invention claimed by the 237 Patent and DIFFERIN.

The Board rejected the argument that DIFFERIN and DIFFERIN XP are separate medicines, holding that it was irrelevant that they were issued separate DINs and NOCs. The Board was also unconvinced of the relevance of evidence that the two medicines were not considered substitutable by provincial formularies or private insurers.

Instead, the Board found that DIFFERIN and DIFFERIN XP are two different concentrations of “the same medicine” and focused on four sets of clinical similarities that it found between them:

  1. They are two different strengths or concentrations of the same active therapeutic ingredient (adapalene), have the same indication, and employ the same mechanism of action;
  2. They are the subjects of the same product monograph and share the common contraindications; warnings and precautions; types of adverse reactions; and guidelines concerning dosage, administration, storage, and stability;
  3. They have the same types of adverse reactions, differing in that they typically appear earlier for patients using DIFFERIN XP, and both medicines are generally well tolerated; and
  4. They are both viewed as appropriate for treatment of certain forms of acne, with different concentrations of adapalene allowing the clinician to tailor the medication. In this context, the PMPRB noted that “no topical acne product…is considered unsubstitutable”, based on expert evidence.

The PMPRB accepted that there was a slightly elevated incidence of adverse reactions as well as higher efficacy for DIFFERIN XP when compared to DIFFERIN. However, the Board concluded that these differences did not outweigh the clinical similarities.

The PMPRB therefore concluded that the 237 Patent pertains to DIFFERIN and ordered Galderma to file the prescribed sales and financial information for DIFFERIN for the period from January 1, 2010 to expiry of the 237 Patent.