Even while their battle over Lipitor continues, Pfizer [1]has sued Ranbaxy Laboratories [2] in District Court for patent infringement of its patent on Accupril (the generic name is quinapril), an anti-hypertensive with annual sales of $550 million. Pfizer is suing on U.S. Patent No. 4,743,450 [3], which covers the use of lactose and microcrystalline cellulose for the stabilization of quinapril.
Earlier, Teva Pharmaceutical Industries Ltd [4]. challenged the same patent in District Court for the District of New Jersey, which was found to be valid until 2007. Teva then launched generic quinapril made by Ranbaxy in the US in December 2004.
You can read our earlier posting here [5] on Ranbaxy’s challenge to the patents held by Pfizer on Lipitor, the world’s largest selling drug with an annual turnover of $10 billion.
See more here [6].