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Pharma in brief - Canada
Federal Court upholds validity of patent for escitalopram
Escitalopram ((+)-Citalopram) (CIPRALEX®)
Nature of case:
Impeachment Action and Counterclaim for Infringement
Date of decision:
Apotex Inc. (“Apotex”) brought an action for impeachment seeking a declaration that Lundbeck’s Canadian Patent No. 1,339,452 (the “’452 Patent”) is invalid. Lundbeck counterclaimed for a declaration of infringement. The ‘452 Patent claims the compound known as Escitalopram or (+)-Citalopram. It is branded in Canada as CIPRALEX®. It has proved useful in the treatment of clinical depression. The ‘452 Patent claims (+)-Citalopram itself, as well as methods to make it and non-toxic salts thereof.
The Court held that the ‘452 Patent is valid. The inventive concept was the two enantiomers of Citalopram, and methods to separate them from the racemate. The state of the art did not disclose how to achieve this result. The Court found that the steps taken by Lundbeck were not obvious to the person skilled in the art, and also required a degree of inventiveness.
Apotex admitted infringement ‘but for’ the validity of the ‘452 Patent. Lundbeck sought and was granted an accounting of Apotex’s profits and a permanent injunction.
This case turned on expert opinion evidence. There was much disagreement between the parties as to the weight to
attach to the opinions of the various experts. The Court stated from the outset that not only were all the experts
superbly qualified to offer expert opinion to the Court, but they were, each and every one, over qualified. The
challenge they faced, and the challenge facing the Court, was whether they were able, in a sense, to reduce their
expertise to that of the skilled person in 1988. The ‘452 Patent
The ‘452 Patent relates to the enantiomers of Citalopram and their use in the treatment of depression in humans. It also relates to methods for obtaining those enantiomers. Claims 1 through 5 relate to (+)-Citalopram itself, including in
salt form and composition, while claims 6 through 11 relate to an intermediate compound and methods of using that
compound to make (+)-Citalopram. History of the Proceedings
Apotex has wanted to market its generic version of (+)-Citalopram for some time. In April 2007, Apotex served a
Notice of Allegation upon Lundbeck Canada Inc. alleging the ‘452 Patent was invalid on various grounds. One of those
grounds, an invalid selection patent, was not pursued by Apotex at this trial. Lundbeck subsequently filed a Notice of
Application seeking an order prohibiting the Minister of Health from issuing a Notice of Compliance to Apotex until the
expiry of the ‘452 Patent. Justice Harrington, who also rendered this decision for the Court, allowed Lundbeck’s
The Court stated that it has developed the practice, where possible and practicable, to assign the trial to the judge who
heard the Prohibition Application. This, without more, does not give rise to a conflict of interest or to an apprehension
of bias. Invalidity
Apotex argued that the claims for (+)-Citalopram as a compound, namely claims 1 through 5, are invalid as they were
anticipated by the prior disclosure of (+)-Citalopram as a component of the racemate. It was common general
knowledge that Citalopram was a racemate containing equal amounts of (+)-Citalopram and (-)-Citalopram and that the
enantiomers might have different therapeutic effects from the other, and from the racemate itself.
The Court held that there was no prior disclosure in that the working of the prior patents would inevitably result in a
racemic mixture, not in separate enantiomers. Therefore, the prior patents did not teach how to resolve Citalopram
and did not disclose the therapeutic effects of (+)-Citalopram. Obviousness
The Court held that Lundbeck was motivated to resolve Citalopram given the common general knowledge that each of
the enantiomers might have different therapeutic effects in the body. The Court held that while motivation would make
it obvious to try to resolve Citalopram, the test is whether it is very plain or, more or less self-evident that what is being
tested ought to work. Motivation does not control the analysis. It was a neutral factor in this case.
The experts cited a number of methods by which (+)-Citalopram could be separated from its racemate, but the
evidence at trial was focused on two methods: chemical resolution and chiral HPLC. For the chemical resolution
technique, the Court held that this route simply gave rise to too many permutations and combinations. For the chiral
HPLC technique, the Court held that given the great many variables, it was not at all obvious to use an HPLC column
and it was not at all obvious that it would work.
A mosaic of prior art was put before the trial judge in an effort to establish that (+)-Citalopram was obvious. The Court
held that no chemist in 1988 would have had the motivation to search for all of this prior art and that even if they had
read everything, they would still have had to connect the dots. A party claiming obviousness must not only be able to
demonstrate that the prior art exists, but must also show how the person of ordinary skill in the art would have been led
to combine the relevant components from the mosaic of prior art. In the Court’s view, an assembly of literature which
“might” have led to (+)-Citalopram involved a considerable degree of inventiveness. Inutility
Apotex alleged that the Pamoic Addition Salt of (+)-Citalopram is toxic and that since claims 1 through 5 all encompass
this salt, the patent falls for inutility. Apotex led no evidence to show whether or not the Pamoic Salt is indeed toxic.
While Lundbeck’s evidence on this issue was “not perfect”, the Court held that it was not unreasonable for a court to
accept imperfect evidence from one side against no evidence at all from the other. The Court opined that just about
everything is toxic if taken in excess. This allegation was dismissed. Insufficient Disclosure
Apotex argued that the ‘452 Patent should be declared void as a result of a statement in the specification which states
“results upon administration to human beings have been very gratifying”. This statement was untrue, as the
enantiomers had not been tested on human beings until after the patent application was filed. The Court found that
this sentence was not a technical one and was not essential, so the patent survived this ground of attack. None of the
experts were misled by the one-liner in the patent specification, given that no human testing was reported in the ‘452
The Court further held that depending on the outcome of Pfizer’s application to the Supreme Court for reconsideration
of its decision in Viagra
, it may well be that it is not even open to Apotex to argue this particular point, as the Court
previously considered Apotex’s argument in the Prohibition Application. Since patent construction is a matter of law, “it
might well be” that Apotex is bound by the construction the Court gave to the ‘452 Patent, upheld by the Federal Court
of Appeal, in the earlier proceeding.
The Court found that Lundbeck had a sound basis for predicting that (+)-Citalopram would be useful in the treatment of
depression in humans. The racemate had already proven to be useful, and the same type of in vivo
and in vitro
to which Citalopram had been subjected were run on (+)-Citalopram, which showed even greater potency.
Apotex urged the Court to find that the ‘452 Patent promised that (+)-Citalopram had greater therapeutic effect than
Citalopram. The Court rejected this argument, as there was no explicit statement either in the disclosure or in the
claims. The Court held that the claim portion of the specification takes precedence over the disclosure portion in that
the disclosure is read so as to understand what is meant by the claims “but not to enlarge or contract the scope of the
claims as written and thus understood”. The insertion of Citalopram in the testing results in the ‘452 Patent was done
as a point of reference and cannot be taken as a promise. Infringement
Having found the ‘452 Patent and each and every one of its claims to be valid, the Court went on to consider the issue
of infringement by both Apotex and Apotex Pharmachem. Both admitted that in the event the patent was found to be
valid in all respects, they have infringed.
Rather than seeking compensatory damages, Lundbeck elected for an accounting of profits. The Court held that the
election is ordinarily accepted unless there are circumstances which would warrant withholding it from the successful
party. There were no such circumstances in this case. Apotex made use of Lundbeck’s intellectual property rights and
must turn over the profits they made. Lundbeck’s claim for punitive damages was rejected. Conclusion
The ‘452 Patent was held to be valid and infringed by Apotex. Lundbeck was awarded an accounting of Apotex’s profits. The Court also issued a permanent injunction prohibiting Apotex from making, selling, distributing, advertising, exposing for sale, stockpiling or possessing for the purposes of the foregoing or importing into Canada (+)-Citalopram prior to the expiration of the ‘452 Patent on September 9, 2014.
Link to decision:
For more information, please contact your IP/Life sciences professional at Norton Rose Canada LLP.
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