Intellectual Property - Patent Dispute - Pharmaceuticals - Patent Invalidity - Generic Drugs
By Rosanna Cooper
The case of Generics (UK) Ltd and Others v H Lundbeck A/S  involved a defendant which was a small research-based pharmaceutical company located in Denmark. It held a European patent (“the Patent”) in respect of an anti-depressant drug, escitalopram. The Patent had a priority date of June 1988.
The drug had been produced by the resolution of a racemate of an existing drug, citalopram, so as to obtain single enantiomers thereof. Accordingly it comprised the pure (+) enantiomer, whereas citalopram comprised both (+) 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 claim 1 compound, and claim 6 related to a method of preparing that compound.
The claimants brought proceedings, seeking the revocation of the patent on account of the prior art drug, citalopram. It fell to be determined by the court whether:
§ Claims 1 and 3 of the Patent were invalid for lack of novelty over the prior art patents;
§ Claims 1, 3 and 6 were invalid for obviousness in the light of those patents and common general knowledge; and
§ Claims 1 and 3 were invalid for insufficiency as citalopram had been an obvious target for resolution.
In relation to obviousness, the claimants submitted that by June 1988, it had been common general knowledge that the biological activity of enantiomers was likely to be different from 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 which it contained.
The court ruled the following:
If the claim in the Patent was simply to the product as such, then the monopoly would indeed cover that product wherever it might be found. However, if the claim was 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 took. It would be unlikely that the patentee intended to cover that which he had expressly described as being 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 come within the description of claim 1, and a pharmaceutical composition comprising the racemate as an active ingredient did not come within the description of claim 3. The Patent not only recognised citalopram, namely the racemate, as old, but was also plainly directed at the isolation of its individual enantiomers.
In the court’s application of established authority to the facts of this case, it was held that claims 1, 3 and 6 were not invalid for obviousness. Investigation of the enantiomers of citalopram had been an obvious goal for the ordinary skilled medicinal chemist in 1988. The difference between the prior art patents and the claims of the Patent was that the former disclosed only the racemate and methods which would only make racemic compounds. They did not describe any method for obtaining single enantiomers of citalopram. It would not have been obvious to resolve citalopram using the adopted method in 1988. The ordinary skilled analytical chemist would have had no practical experience of that method and the ordinary skilled medicinal chemist would probably not have heard of it.
In the circumstances of this case, claims 1 and 3 of the Patent were invalid for insufficiency. The inventive step taken by the defendant had not been deciding to separate the enantiomers of citalopram, but finding a way it could be done. Claims 1 and 3 of the Patent covered all ways of making the (+) enantiomer. The first person to find a way of achieving an obviously desirable goal was not permitted to monopolise every other way of doing so. Claims 1 and 3 were therefore too broad. The court held that they extended beyond any technical contribution made by the defendant.
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