AstraZeneca AB v Apotex Pty Ltd

AstraZeneca AB and AstraZeneca Pty Limited (together "AstraZeneca") appealed to the High Court of Australia concerning Australian Patent No 200023051. The patent, referred to as the "051 patent" or "low dose patent," claimed a method of treatment for hypercholesterolemia, hyperlipoproteinemia, and atherosclerosis by administering rosuvastatin or its pharmaceutically acceptable salts within a specific low dosage range. The dispute centred on whether this claimed invention involved an inventive step, specifically whether it was obvious in light of the prior art.

The central legal issue before the High Court was whether the invention, as defined by the claims of the 051 patent, possessed an inventive step. This required the Court to determine if the invention was obvious to a person skilled in the relevant art, considering common general knowledge and the prior art documents. Specifically, the Court had to assess whether the prior art documents were properly ascertained, understood, and regarded as relevant by such a skilled person, and whether information from different prior art documents could be used to establish the relevance of information within another.

The High Court considered expert evidence regarding the prior art, including a 1997 article by Watanabe and others which disclosed rosuvastatin (then designated S-4522) and its potent HMG-CoA reductase inhibitory activity. The Court noted that the patent specification identified the problem it sought to solve as finding alternative statins with improved efficacy and safety profiles at particular dosages. The patent claimed that at the specified low dosages of 5-10 milligrams per day, rosuvastatin lowered LDL cholesterol to an unexpectedly greater degree and without significant adverse side effects. The Court ultimately found that AstraZeneca's appeals failed on the ground of inventive step.

The appeals brought by AstraZeneca were dismissed with costs.