On April 26, 2006, a trial judge of the Federal Court found that the lisinopril patent (No. 1,275,350) is valid and that it has been infringed by Apotex (Merck and AstraZeneca v. Apotex, 2006 FC 524).
This patent infringement action was brought by Merck (patentee and certain related companies) and AstraZeneca (licensee) against Apotex in 1996. The parties sell lisinopril in Canada under the trademarks Apo-Lisinopril, ZESTRIL (AstraZeneca) and PRINIVIL (Merck).
Infringement
Apotex had admitted infringement but raised four defences relating to certain quantities. The Judge rejected the arguments based on section 56 of the Patent Act and a compulsory licence that had been extinguished.
However, he found that certain quantities were exempt in view of section 55.2(1) of the Patent Act, which provides:
55.2 (1) It is not an infringement of a patent for any person to make, construct, use or sell the patented invention solely for uses reasonably related to the development and submission of information required under any law of Canada, a province or a country other than Canada that regulates the manufacture, construction, use or sale of any product.
The Judge found that lisinopril quantities used for the purpose of obtaining regulatory approval were exempt, including those that were not referenced in the submissions but were in one way or another directed to that purpose. The Judge additionally found that material routinely taken by Apotex as samples from incoming raw material and of the finished products, stored in the event that they are required for future reference in accordance with regulatory requirements, were also exempt.
Finally, the Judge found that Apotex’s use of lisinopril in ongoing research and development of alternate formulae, alternate techniques for tablet making and the like, falls within a "fair dealing" exemption to infringement.
Validity
The ‘350 patent issued on October 16, 1990 from a voluntary divisional application filed on August 1, 1989 from a parent application filed in Canada on December 6, 1979.
Apotex argued that the patent was invalid on three bases: 1. It issued from an improper divisional application; 2. double patenting in view of an earlier issued patent relating to a combination of enalapril and hydrochlorothiazide; and 3. wilful delay by Merck in prosecution of the application.
The Judge held that Apotex was estopped from raising these validity attacks in view of prior litigation involving Apotex, Merck and another patent directed to enalapril. The Judge held that the same attacks could have been raised in the earlier litigation since the enalapril patent arose from the same parent application and issued on the same day as the lisinopril patent.
The Judge nonetheless dealt with the validity attacks on the merits.
On the improper divisional attack, the Judge rejected Apotex’s argument that the parent application did not both describe and claim more than one invention, i.e. that it only described one invention, the class, of which lisinopril was but an example. He also held that even if several patents claiming the same invention had been granted, a sufficient remedy exists in the application of double patenting.
The double patenting attack was rejected as lisinopril and enalapril were found to be separate inventions.
Finally, the wilful delay attack was rejected on the basis of lack of evidence.
Apotex may appeal, as of right.
Nancy P. Pei, Toronto
As an addendum to this article, Apotex and AstraZeneca have now appealed and Merck has cross-appealed the trial judge’s decision. Furthermore, on May 25, 2005, a Judge of the Federal Court of Appeal dismissed Apotex’s motion for a stay of this decision, finding that "Apotex' evidence on the question of irreparable harm is too flimsy and speculative to warrant granting a stay". Merck and AstraZeneca had also offered an undertaking as to damages, should Apotex’s appeal be allowed (Apotex v. Merck and AstraZeneca, 2006 FCA 198).