12:00 AM
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Nov 10, 2003
 |  BioCentury  |  Regulation

Reddy or not

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 contend that FDA's interpretation of 505(b)(2) is incorrect, and that an innovator's data can only be referenced to issue an ANDA for a generic copy of an off-patent product.
PFE has vowed to sue FDA to reverse the approval of Amvaz. Although the case involves two small molecule drugs, the resulting legal decision could impose a roadblock or help clear the path to the use of 505(b)(2) for the approval of follow-on biologics (see BioCentury, April 15, 2002). Amvaz also could provide an interesting test case for marketing biogenerics that, like Amvaz, could be approved based on their similarity to an approved product, but might not be automatically substitutable by pharmacists.
The dispute over Amvaz involves two distinct issues. One is the broad question of whether FDA can allow NDA applicants to use 505(b)(2) to reference an innovator's proprietary safety and efficacy data. The second...

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