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Prosecution history is not admissible to rebut representations made by a licensee

January 28, 2021


The Federal Court recently released its decision in Allergan Inc. v. Sandoz Canada Inc., 2020 FC 1189, finding that Sandoz Canada Inc. (“Sandoz”) would not infringe a patent licensed to Allergan Inc. (“Allergan”) pertaining to RAPAFLO® for its generic silodosin product (the “Sandoz Product”).


RAPAFLO® is a drug used for the treatment of benign prostatic hyperplasia, and contains silodosin. Allergan is authorized to manufacture, market, and sell RAPAFLO® capsules in Canada pursuant to a series of Notices of Compliance issued by Health Canada. Kissei Pharmaceutical Co. Ltd. (“Kissei”) is the owner of the 002 Patent.

The 002 Patent and its Essential Elements

The 002 Patent claims a solid oral dosage form capsule for the treatment of dysuria which comprises silodosin and specific excipients, manufactured in a manner that achieves a defined rapid dissolution profile.

Though the Sandoz Product contains many of the same ingredients as RAPAFLO® it does not contain “granules” or involve “granulating” or a “wet granulation process” (collectively, the “Wet Granulation Elements”). The Sandoz Product is made by a “dry” formulation method.

Therefore, the Court had to determine whether the Wet Granulation Elements were essential to the claims in dispute and found that the Wet Granulation Elements were essential for the following reasons:

  • There was a clear intention that the inventors of the 002 Patent intended the Wet Granulation Elements to be essential;

  • The 002 Patent taught away from the use of dry processes; and

  • The Skilled Person would not have understood that a dry process could be substituted for the wet granulation process without materially affecting the working of the invention.

Sandoz sought to rely on the prosecution file history for the 002 Patent and section 53.1 of the Patent Act to rebut a representation made in litigation by the licensee (Allergan). The Court held that the provision is limited to certain written communications to be admitted into evidence to rebut any representation made by the patentee in an action or proceeding, in respect of the construction of a claim in a patent that is at issue in the action or proceeding. As the patentee was Kissei, which had not made any representation to the Court with respect to the construction of the 002 Patent, the Court determined that subsection 53.1(1) could not be invoked.

Obviousness and Infringement

The Court then undertook an obviousness assessment, ultimately finding that the patent was not obvious.

However, as the Court’s earlier finding was that the Wet Granulation Elements were essential elements of the claims, the Court held that the Sandoz Product would not infringe the 002 Patent.


Authors: Jaclyn Tilak and Emma Baumann


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