Date for assessing sufficiency of the specification is the publication date

zoledronic acid

On March 19, 2013, Justice Hughes of the Federal Court of Canada released his Reasons for Judgment in a prohibition application between Novartis Pharmaceuticals Canada Inc. and Teva Canada Limited involving Canadian Patents Nos. 1, 338, 895 and 1, 338, 937 listed on the Patent Register against Novartis’ ZOMETA intravenous zoledronic acid (4 mg/5 ml and 5 mg/100 ml) infusion products. Both patents were filed prior to October 1989 and are therefore governed by  the “Old Act“.

895 Patent

The 895 Patent, Issued to Boehringer, was generally directed to new disphosphonic acid derivatives that differ from prior art diphosphonic acid compounds by the number of carbons separating the diphsophonate residue and the heterocyclic ring. Claim 14 of the 895 Patent, the only claim at issue in the prohibition application, claims a genus of at least 1.2 million compounds, including zoledronic acid, having the following core structure:

Justice Hughes concluded that the inventive concept of Claim 14 of the 895 Patent was a family of about 1.2 Million members.

937 Patent

The 937 Patent, issued to Ciba-Geigy  (later acquired by Novartis) contains only 2  directed to zoledronic acid , salts and pharmaceutical compositions thereof.

Justice Hughes, distinguishing the analysis of the Supreme Court of Canada in Teva sildenafil, held that the inventive concept  of the 937 Patent was that zoldedronate is a useful inhibitor of bone resorption in rats and as such, is suitable for use as a medicament in the treatment of diseases in humans associated with the impairment of calcium metabolism

Old Act Conflict

Under the Old Act, two co-pending applications directed to the same subject matter would be placed into a conflict proceeding to determine which application had the earlier invention date. The Ciba Geigy and Boehringer settled the conflict with Boehringer retaining the genus claims of the 895 Patent  and Ciba-Geigy keeping the claims to zoledronic acid in the 937 Patent. .


Justice Hughes held that it would not be more or less self evident that the genus of compounds claimed in the 895 Patent or zoledronic acid claimed in the 937 Patent ought to work as of thier respective dates of invention:

[160] I agree that researchers working in the area may have perceived a “hole”, as Teva’s Counsel put it, in the state of the art in that the “one carbon linker” had not been explored. However, given the numerous choices for what are described as the R1 and R2 positions, even if some are more apparent than others, and given that there was no real predictability as to what might work. This would be the same whether one considers common general knowledge or state of the art. I cannot conclude that it was “self evident” that what is claimed in either patent ought to work.


895 Patent

Prior to the filing date  of the 895 Patent, the inventors had made and tested only  one compound, which was not zoledronic acid, within the scope of claims 14.  Justice Hughes held that the invention date of the 895 Patent was no earlier than the draft of the Convention priority application, June 23, 1986.  Justice Hughes held that the utility of  the 1.2 million compounds of claim 14 could not  be predicted on the demonstrated utility of a single compound. Since the 895 inventors had not establish the utility of the genus by the Canadian filing date and there was nothing in the description of the 895 Patent that would enable a sound prediction across this genus, Justice Hughes held that Teva’s allegation of inutility was justified.

937 Patent

In July 1987, after the Convention priorty date but before the Candian filing date, the 937 inventors has made and tested zoledronic acid in rats  such that Teva’s allegation of inutility against was not justified.

Sufficiency of Specifications

Teva has alleged that the specification of the 895 and 937 Patents were insufficient for failing to enable the skilled person, having only the specification, to put the invention into practice.  Justice Hughes found that  the 895 Patent was insufficient for the same reasons  discussed for utility.

For the 937 Patent, the date at which sufficiency is to be determined was important.  When the 937 Application was filed in Canada, it, like the 895 Patent, contained claims to a large genus of bisphosphonates.  As a result of he conflict withe the 895 Application, the 937 Patent ultimately issued with claims directed only to zoledronic.  After noting that Canadian law on the proper date for assessing sufficiency was not clear considering conflicting U.K jurisprudence, Justice Hughes concluded that the publication date is the most appropriate date for determining sufficiency in Canada:

[188] I find that the most appropriate date for consideration of sufficiency of a Canadian patent is, as found by Buckley LJ in Standard Brands, as referred to by Lord Hoffman in Biogen, that of the date of publication. That is the date that the public is seized with the application. That is the date that the person applying for the patent has committed to claims for the invention in a manner available to the public. In the case of an “old” Act patent, this would be the day that the patent was issued and granted. In the case of a “new” Act patent, it would be the date of publication.

Since the 937 Patent was published upon issuance with claims only to zoledronic acid, Justice Hughes held that Teva’s allegation of insufficiency was not justified and prohibited the Minster of Health from approving Teva’s zoledronic acid products until the February 2014 expiration of the 937 Patent.

A copy of Justice Hughes’ Reasons for Judgment may be found here.