Selection Patent Valid Says Pfizer Canada Inc v Ratiopharm

Leave to appeal to the Supreme Court of Canada the decision of the Federal Court of Appeal in Pfizer Canada Inc v Canada (Minister of Health) and Ratiopharm Inc was recently denied. The case involved a rarely visited area of Canadian patent law – the validity of selection patents. The inventive step in a selection patent lies in the discovery that one or more members of a previously known class of products possess some special advantage for a particular purpose that could not have been predicted before the discovery was made. The purpose of selection patents is to encourage researchers to further use their inventive skills so as to discover new advantages for compounds within a known class. In this case, the patent owned by Pfizer Canada Inc (Pfizer) covered besylate, a salt of amlodipine, that had been selected from some 80 pharmaceutically acceptable salts. However, selection patents are not to be granted for mere "verification", that is, no invention exists in simply confirming predicted or predictable qualities of known substances, compounds or components that have already been discovered and made. In early 2006, Justice von Finckenstein of the Federal Court of Canada determined that this is exactly what Pfizer had done and dismissed its application for an Order prohibiting the Minister from issuing a Notice of Compliance to Ratiopharm on the basis that Canadian Patent No 1,321,393 was invalid as a selection patent and not patentably distinct from one of Pfizer's earlier patents – Canadian Patent No 1,253,865 (which later expired). He determined that Pfizer simply tested the degree of known characteristics of the salt and then claimed that these characteristics were unique. On Pfizer's appeal, the decision was reversed by the Federal Court of Appeal which determined that, in reaching his decision, Justice von Finckenstein had set the threshold of what constitutes a "special advantage" of a compound too high because such an advantage could also include a disadvantage to be avoided. Justice Malone of the Federal Court of Appeal held that the besylate salt indeed did have advantages in terms of stability, solubility, non-hygroscopicity and processability and therefore, in his view, the patent claiming it was a valid selection patent. For the full text of the Federal Court of Appeal decision, see: http://decisions.fca-caf.gc.ca/en/2006/2006fca214/2006fca214.html Summary by: Heather Watts