Intellectual Property – Patent Dispute – Pharmaceutical Products – Patent Nullity – Generic Drugs

The case of Generics (UK) Ltd and others v H Lundbeck A/S [2007] involved a defendant who was a small research-based pharmaceutical company located in Denmark. He held a European patent (“the Patent”) regarding an antidepressant drug, escitalopram. The patent had a priority date of June 1988.

The drug had been produced by resolution of a racemate of an existing drug, citalopram, to obtain individual enantiomers thereof. Therefore, it comprised the pure (+) enantiomer, while citalopram comprised both the (+) and (-) enantiomers. The patent comprised seven claims. Claim 1 was a product claim directed to the (+) enantiomer, claim 3 related to a pharmaceutical composition containing the compound of claim 1, and claim 6 related to a method of preparing that compound.

The plaintiffs initiated actions, requesting the revocation of the patent due to the state-of-the-art drug, citalopram. It would be for the court to determine whether:

§ Claims 1 and 3 of the Patent were not valid due to lack of novelty on the patents of the state of the art;

§ Claims 1, 3, and 6 were obviously not valid in light of those patents and common general knowledge; Y

§ Claims 1 and 3 were invalid due to insufficiency as citalopram had been an obvious target for resolution.

Regarding the obvious, the plaintiffs contended that as of June 1988, it was common knowledge that the biological activity of the enantiomers was likely to be different from that of the racemate and that, for any racemate under development as a potential therapeutic agent, it was highly desirable to resolve the racemate to determine the properties of the enantiomers it contained.

The court ruled as follows:

If the claim in the Patent was simply about the product as such, then the monopoly would certainly cover that product wherever it is found. However, if the claim refers to the isolated product or to a pharmaceutical composition comprising that isolated product as an active ingredient, then the monopoly would not extend to that product, whatever form it takes. It would be unlikely that the patent holder intended to cover what he had expressly described as old. Therefore, in the circumstances of this case, claims 1 and 3 of the Patent were not invalid for lack of novelty. The citalopram racemate did not fall within the description of claim 1, and a pharmaceutical composition comprising the racemate as an active ingredient did not fall within the description of claim 3. The Patent not only recognized citalopram, that is, the racemate , as ancient, but was also clearly aimed at the isolation of its individual enantiomers.

In the court’s application of established authority to the facts of this case, it held that assertions 1, 3, and 6 were not obviously invalid. Investigation of citalopram enantiomers had been an obvious goal for the common qualified medicinal chemist in 1988. The difference between the prior art patents and the Patent claims was that the former disclosed only the racemate and methods that would only produce racemic compounds. They did not describe any method to obtain individual citalopram enantiomers. It would not have been obvious to resolve citalopram using the method adopted in 1988. The qualified analytical chemist would not have had practical experience with that method and the qualified medical chemist would probably not have heard of it.

In the circumstances of this case, claims 1 and 3 of the Patent were invalid due to insufficiency. The defendant’s inventive step had not been to decide to separate citalopram enantiomers, but to find a way to do so. Claims 1 and 3 of the patent covered all ways of making the (+) enantiomer. The first person to find a way to achieve an obviously desirable goal was not allowed to monopolize all other ways of doing it. Therefore, claims 1 and 3 were too broad. The court held that they extended beyond any technical contribution made by the defendant.

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© RT COOPERS, 2007. This Information Note does not provide a comprehensive or complete statement of the law relating to the issues discussed nor does it constitute legal advice. Its sole purpose is to highlight general issues. Specialized legal advice should always be sought in relation to particular circumstances.