Application for Prohibition (PMNOC) Granted for Latanoprost/XALATAN®
Pfizer Canada Inc. and Pharmacia Atkiebolag v. Canada(Minister of Health) and Pharmascience Inc., 2009 FC 1294 (Heneghan, J.)

December 18, 2009

Brian Daley, Judith Robinson and Kavita Ramamoorthy for the Applicant, Pfizer Canada Inc.
Carol Hitchman and Esther Jeon for the Respondent, Pharmascience Inc.
No-one appearing for the Minister of Health

In a PMNOC Application, Pfizer successfully brought an application to prevent the issuance of an NOC for the anti-glaucoma drug Latanoprost, a prostaglandin derivative, to Pharmascience. Pharmascience had alleged in their notice of allegation (“NOA”) that Pfizer’s Patent 1,339,132 (“Patent”) was invalid for anticipation, obviousness, lack of utility, lack of sound prediction, overbreadth and lack of sufficiency, and further alleged non-infringement of the Patent.

A compound claim and several use claims in the patent were relied on by Pfizer. As an ‘old act’ patent, the claims were construed as at July 29, 1997, the issue date of the patent. Pharmascience’s primary defence was the Gillette Defence, as the drug it used was directly claimed by claim 19 of the Patent. The Court found that the isopropyl compound disclosed in the patent and claimed in claim 19 was not previously known and that therefore the patent was not anticipated, and the Gillette Defence was unavailable. 

Citing the recent decision of the Supreme Court of Canada in Sanofi-Synthelabo Canada Inc. v.  Apotex Inc. (2008), and making particular reference to an award won by the inventor of Latanoprost, the Court held that the compound was not obvious. The Court also cited the general unpredictability of medicines in this area, and the unexpected property of Latanoprost to not cause as severe side effects as prior drugs of the same class. The Court followed the Federal Court of Appeal’s decision in Pfizer Canada Inc. v. Canada (Minister of Health) (2008) holding that it was not necessary to set out in a patent why and how an invention is useful, and held based on expert and inventor evidence that the patent was useful and soundly predicted as at its filing date of September 12, 1989. As the claims (in particular the compound claim) did not claim a particular benefit, they were not overbroad.

By: Ken Clark, Aird & Berlis LLP