Pfizer's Patent on Norvasc Survives Challenge by Synthon

The U.S. District Court for the Middle District of North Carolina recently found Pfizer's patent on the active ingredient of Norvasc, amlodipine besylate, valid and infringed by Synthon's generic equivalent.  Norvasc, a treatment for hypertension, has annual sales of nearly $5 billion.

In the opinion, Judge James A. Beaty, Jr. concluded that Pfizer's U.S. Patent No. 4,879,303 was not invalid for obviousness, lack of written description, or double patenting.  According to Pfizer's press release announcing the court decision, in January the U.S. District Court for the Northern District of Illinois found the same patent valid and infringed by Apotex.

As reported in Orange Book Blog last month, the U.S. District Court for the Eastern District of Virginia recently found that Pfizer did not infringe Synthon's patent on a process for making amlipodine.