Dr Reddy’s Laboratories has announced that the company has filed an Abbreviated New Drug Application (ANDA) with the United States Food and Drug Administration for Amlodipine Besylate tablets 2.5, 5 and 10 mg, with a Paragraph IV certification on the two Orange Book patents listed for the drug.

Dr Reddy’s notified Pfizer, upon which the latter filed a lawsuit against the company in the United States District Court of New York alleging patent infringement on the two Orange Book patents.

Amlodipine Besylate is the generic version of Pfizer’s Norvasc and is indicated for the treatment of hypertension and angina. The brand had annual sales in the United States of approximately $2 billion.