"Esomeprazole" – The Eastern High Court acquits Krka for patent infringement

AstraZeneca asserted claim 1 and claim 9 of the patent, both claiming the magnesium salt of esomeprazole with an optical purity of at least 99.8% enantiomeric excess (e.e.). 

It was undisputed that Krka's medicament, as well as the finished magnesium salt of esomeprazole that Krka subsequently used to manufacture its medicament, did not contain the magnesium salt of esomeprazole with an optical purity of at least 99.8% e.e. AstraZeneca argued nonetheless that Krka had:

• literally infringed claim 1 because magnesium salt of esomeprazole with an optical purity of at least 99.8% e.e. was present, as isolated salt crystals, during Krka's chemical process of manufacturing the magnesium salt of esomeprazole that was subsequently going to be used for manufacturing Krka's medicament
• infringed claim 1 and claim 9 under the doctrine of equivalence, since Krka had utilized the central novel feature of these patent claims, which AstraZeneca argued was the magnesium salt of esomeprazole "in very high optical purity".

These assertions were both rejected by the Eastern High Court which, contrary to the first instance decision, found that claim 1 was in the format of a "Swiss-type"-patent claim and that there were no indications in claim 1 or in the patent specification that this claim covered prior manufacturing steps of the magnesium salt of esomeprazole that subsequently forms part of the manufacture of the medicament. 

The High Court stated that the only relevant time for assessing the level of optical purity of the magnesium salt of esomeprazole within the meaning of claim 1 is the time when this salt is used for manufacturing the medicament, and, at that point in time, Krka's magnesium salt of esomeprazole did not have the required purity. 

The Maritime and Commercial High Court had found that claim 1 was a process claim and therefore also offered protection for purity levels of the salt, as an intermediate, during the chemical process of manufacturing the magnesium salt of esomeprazole that Krka subsequently used for the manufacture of its medicament. This interpretation was rejected by the High Court. 

Also, the High Court found that, in light of the patent description and the prosecution history, the central novel feature of claim 1 and claim 9 is the magnesium salt of esomeprazole with a specific optical purity level of at least 99.8% e.e. Therefore, the was no basis for extending the scope of protection beyond this purity level and since Krka's medicament and the esomeprazole magnesium salt that was used to manufacture the medicament did not have this degree of optical purity, Krka had not infringed under the doctrine of equivalence.

AstraZeneca claimed DKK 67,000,000 in damages for past patent infringement – and had been awarded DKK 50,000,000 in damages as part of the first instance judgement – but this claim was rejected by the Eastern High Court as part of the acquittal of Krka.  

Kromann Reumert, by Nicolai Lindgreen and Nicolaj Bording, acted for Krka in the appeal proceedings.