FDA has announced approval of a new calcium channel blocker product that could, if it withstands legal challenges, set a precedent for a new type of assault on the market exclusivity periods for patented small molecule drugs. The NDA, granted last week to Dr. Reddy's Laboratories Inc. for Amvaz amlodipine maleate, a formulation of Pfizer Inc.'s Norvasc amlodipine besylate, has brought to the boil a long-simmering dispute over the correct interpretation of an obscure bit of law. FDA's interpretation could effectively lop two or three years off the period of market exclusivity granted to new drugs.
The NDA was issued under section 505(b)(2) of the Food, Drug and Cosmetic Act. According to FDA, 505(b)(2) allowed DRY (Hyderabad, India) to reference proprietary safety and efficacy data that PFE submitted as part of the Norvasc NDA. PFE (New York, N.Y.) and other pharmaceutical companies
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