Patent Law Practice Center

AstraZeneca Loses at the Federal Circuit on Omeprazole

On December 19, 2013, Hanmi Pharmaceuticals received good news in the form of a decision by the U.S. Court of Appeals for the Federal Circuit (CAFC). Invoking 35 U.S.C. §271(e)(2), AstraZeneca had alleged that a drug Hanmi proposed to market falls within claims of U.S. Patent Nos. 5,714,504 and 5,877,192. After the district court construed the claim terms “alkaline salt” in the ’504 patent and “pharmaceutically acceptable salt” in the ’192 patent, the parties consented to the entry of a final judgment of non-infringement based on the constructions. This case is of particular interest to the industry because omeprazole is the active ingredient in the popular over-the-counter heartburn medication know as Prilosec.

Creating a salt out of omeprazole can enhance stability during storage and transportation, a useful property in pharmaceutical compounds.  AstraZeneca discovered that certain salts of an omeprazole enantiomer have improved pharmacokinetic and metabolic properties which will give an improved therapeutic profile such as a lower degree of interindividual variation. During prosecution, AstraZeneca conducted experiments that led it to conclude that one of the two enantiomers gave particularly good results. The preferred enantiomer became known as “esomeprazole.”