AstraZeneca claims quashed in heartburn drug patent case

An appeals court has ruled in favour of Hanmi Pharmaceuticals in a patent dispute over AstraZeneca’s best-selling acid reflux drug Nexium (esomeprazole magnesium).

The US Court of Appeals for the Federal Circuit upheld a lower court’s ruling that South Korean drug maker Hanmi did not infringe on a patent held by AstraZeneca for esomeprazole magnesium. AstraZeneca had accused Hanmi of patent infringement as a result of Hanmi’s development of an esomeprazole strontium drug, a proton pump inhibitor that is not automatically substitutable for Nexium in pharmacies. However, the court decided that Hanmi’s strontium salt does not infringe AstraZeneca’s patent because that patent only applies to the magnesium salt found in Nexium. Nexium had sales of almost $5 billion (£3 billion) in 2010.