AstraZeneca has filed patent infringement actions in United States District Court, District of Delaware, against seven generic drug manufacturers, which have submitted Abbreviated New Drug Applications (ANDAs) for Crestor.

On 1st November 2007, AstraZeneca has announced its receipt of a notice-letter from Cobalt Pharmaceuticals, Inc., notifying AstraZeneca that Cobalt had submitted an ANDA to the US FDA. Cobalt's ANDA sought approval to market generic versions of Crestor tablets prior to the expiration of patents covering Crestor tablets. Cobalt's ANDA contained a paragraph IV certification alleging that the US patents owned or licensed by AstraZeneca, and listed in the FDA's Orange Book referencing Crestor, were not infringed or that the patents were otherwise invalid or unenforceable.

Since receiving Cobalt's notice-letter, AstraZeneca has received similar paragraph IV certification notice-letters from eight additional generic drug manufacturers. AstraZeneca received notice letters from Teva Pharmaceuticals, USA on October 31, 2007; Aurobindo Pharma Limited (Aurobindo) on November 5, 2007; Apotex, Inc. (Apotex) on November 6, 2007 and December 5, 2007; Par Pharmaceutical (Par) on November 6, 2007; Sandoz Inc. (Sandoz) on November 12, 2007; Mylan Pharmaceuticals Inc. (Mylan) on November 15, 2007; Glenmark Pharmaceuticals, Inc. USA (Glenmark) on November 15, 2007; and Sun Pharmaceutical Industries Ltd. (Sun) on November 19, 2007.

Each of the eight additional generic drug companies has notified AstraZeneca that it has submitted an ANDA to the FDA seeking approval to market generic versions of Crestor tablets before the expiration of the US patents owned or licensed by AstraZeneca. Each notice-letter contained a paragraph IV certification notice alleging that one or more of the three Orange Book listed US patents referencing Crestor in the FDA's Orange Book was not infringed or otherwise invalid or unenforceable.

Based on these various ANDA filings and paragraph IV certifications, on 11th December 2007 AstraZeneca filed individual patent infringement actions in US district court, district of Delaware, against Aurobindo, Apotex, Cobalt, Par, Sandoz, Mylan, and Sun, alleging infringement of US No. RE 37,314 (the '314 patent). AstraZeneca licenses the '314 patent from Shionogi & Co. Ltd.