On 23 February 2022, the Federal Court issued its public reasons for judgment in a patent infringement action pursuant to subsection 6(1) of the Patented Medicines (Notice of Compliance) Regulations relating to risedronate sodium (Allergan's Actonel DR).(1) Justice Kane found Canadian Patent No. 2,602,188 (the 188 patent) valid but not infringed.
The 188 patent relates to a dosage form of a bisphosphonate – specifically, risedronate – that displays pharmaceutically effective absorption when taken with or without food. At the time of the priority filing date of the 188 patent, oral bisphosphonates used to treat osteoporosis, including risedronate, were known to be poorly absorbed, especially when taken with food. As a result, these drugs were required to be taken on an empty stomach. The inventors of the 188 patent had sought to overcome this issue, termed the "food effect".
The claims asserted by Allergan were all dependent on claim one, which recites "[a]n oral dosage form of a bisphosphonate for use with or without food or beverage intake". Claim one further recites that the oral dosage form comprises a pharmaceutical composition containing risedronate and ethylenediaminetetraacetic acid (EDTA) in a specified molar ratio and an enteric coating to provide for "pharmaceutically effective absorption of the bisphosphonate with or without food or beverage intake".
The Court found that the 188 patent was not anticipated by a Brazilian patent application referenced in the description of the 188 patent (Brazilian Patent Application 0106601 (BR 601)). While BR 601 disclosed formulations that overlap with those contained in the 188 patent, BR 601 did not provide sufficient guidance to direct the skilled person to the formulations of the 188 patent, address the food effect or disclose that pharmaceutically effective absorption would be achieved with or without food. With respect to enablement, the Court found that a skilled person relying on BR 601 would not be able to work the invention of the 188 patent without trial and error and significant experimentation, including human clinical trials.
The Court addressed BR 601 again in finding that the 188 patent was not obvious. Per the Federal Court of Appeal's guidance in Hospira Healthcare Corporation v Kennedy Trust for Rheumatology Research,(2) Justice Kane included BR 601 in the mosaic of the prior art considered to determine obviousness, while the likelihood of a skilled person locating BR 601 in a reasonably diligent search was stated as being relevant to the question of whether a skilled person would have thought to combine the document with other prior art. Based on the totality of evidence, including expert evidence relating to BR 601 and the use of EDTA and enteric coatings, the Court found that a skilled person would not have been led directly and without difficulty to combine the elements of the asserted claims of the 188 patent. The Court also found that it would not have been obvious to try to obtain the claimed invention.
Apotex's remaining challenges to the validity of the 188 patent – inutility, insufficiency and overbreadth – were all rejected.
The Court found that Apotex would not infringe the asserted claims of the 188 patent by making, constructing, using or selling its risedronate product, nor would Apotex induce infringement of the asserted claims.
The Court's finding of non-infringement turned on its construction of the asserted claims. Allergan asserted that the claimed dosage form was a product suitable for use with or without food – that is, a dosage form containing specific ingredients and a specific coating. However, the Court found that there was no need to read "suitable for use" into the claims and that an essential element of the asserted claims was that the oral dosage form can be taken with or without food at the choice of the patient. The asserted claims did not simply claim a product; rather, they claimed use of an oral dosage form that can be taken in one of two manners at the preference of the patient.
As Apotex's proposed product monograph – consistent with the Actonel DR product monograph – indicated that its risedronate product should be taken with food and may result in abdominal pain if taken without food, the Court found that the Apotex product did not fall within the scope of the asserted claims. Likewise, in view of both expert evidence and Apotex's proposed product monograph, the Court found that Apotex would not induce infringement of the asserted claims.
Allergan has appealed.
For further information on this topic please contact Malcolm Harvey at Smart & Biggar by telephone (+1 416 593 5514) or email ([email protected]). The Smart & Biggar website can be accessed at www.smartbiggar.ca.
(1) Allergan Inc v Apotex Inc, 2022 FC 260.
(2) 2020 FCA 30.