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NO – KRKA Sverige AB and Krka D.D. Novo Mesto v. AstraZeneca AB (esomeprazole)

21 Feb 2014

KRKA Sverige AB and Krka D.D. Novo Mesto v. AstraZeneca AB, Borgarting Court of Appeal, Norway, 24 January 2014, Case No. 12-103103ASD-BORG/02

On 24 January 2014 Borgarting Court of Appeal rendered its decision in a case between Krka Sverige AB and Krka D.D. Novo Mesto (appellants) and AstraZeneca AB (respondent) regarding AstraZeneca's patent NO 307378. The patent concerns the active enantiomer esomeprazole, and the case considers infringement of the patent only.

The relevant claim of the patent (claim 10) concerns a pharmaceutical product containing an "optically pure compound" according to claim 1-4. Claim 1-4 concerns an optically pure compound of various salt forms of esomeprazole.

The purity of the substance can be measured by its enantiomeric excess, which describes the amount of the desired S-enantiomer compared to the amount of the undesired enantiomer R-omeprazole.

Krka launched a generic product containing esomeprazole, which AstraZeneca alleged infringed its patent NO 307378.

The question before the court was whether Krka's pharmaceutical esomeprazole product with an enantiomeric excess between 98,8 % and 99,5 %, could be classified as "optically pure". If so, Krka's marketing of Esomeprazole Krka represented a patent infringement. Krka argued that the patent only applies to substances with an optical purity of 99, 8 % and higher.


The Court of Appeal found that the term "optically pure" did not have an exact meaning within the science of organic chemistry. For a person skilled in the art the term was not limited to a purity of 99, 8 % and higher.

In the patent description the substance is described as being "substantially free of" R-omeprazole. Additionally, the description states that the enantiomer of omeprazole "can be obtained in a very high optical purity, namely ≥ 99, 8 % e.e." The Court of Appeal found that the latter term express a higher purity grade than the term "substantially free from". When reading the two terms in conjunction, the Court of Appeal found that the term "substantially free from" also included purity degrees lower than 99, 8 % e.e.

The patent claims did not specify the exact lower limit to what grade of purity the substance covered by the patent must have. Krka alleged that this ambiguity should be in disfavour of AstraZenecas interpretation. The Court of Appeal did not find such ambiguity decisive, stating firstly that the patent had been granted by the Norwegian Industrial Property Office (NIPO), and secondly, that the purpose of the invention was to achieve an optical purity high enough to achieve the desired medical effect. A lower limit was not important for the inventor or NIPO. As such, Krka's product was considered to be substantially free of" R-omeprazole, and thus should be considered as "optically pure". Subsequently, the marketing of Krka's product was found to infringe AstraZeneca's patent 307 378.

Read the decision (in Norwegian) here.

Head note: Håkon Austdal and Thomas Hagen