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# FDA Denies Amdra Petition on Albenza Bioquivalence
- URL: https://www.fdaweb.com/fda-denies-amdra-petition-on-albenza-bioquivalence/
- Published: 2016-02-22T12:00:00.000Z
- Updated: 2026-09-15T02:37:53.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5134847

> FDA has denied an Amedra Pharmaceuticals [petition](http://www.regulations.gov/?ref=fdaweb.com#!documentDetail;D=FDA-2013-P-0766-0001) asking the agency not to approve any ANDA referencing Albenza (albendazole) unless it meets specific criteria listed in the petition. The petition objected to a draft guidance that instructed ANDA applicants to measure both albendazole and its active metabolite, albendazole sulfoxide and recommended that bioequivalence may be demonstrated based only on the albendazole data. Amedra said this would not be sufficient because of the nature of the drug in terms of the way it is absorbed into the bloodstream, how it is metabolized, and its mechanism of action.  
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> In [denying ](http://www.regulations.gov/?ref=fdaweb.com#!documentDetail;D=FDA-2013-P-0766-0006)the petition, FDA said it has concluded that a statistical comparison of albendazole’s concentration-time profile data is the most sensitive, accurate and reproducible method for demonstrating that a proposed generic is bioequivalent to Albenza. “As the parent drug, albendazole is inherently more sensitive to formulation and manufacturing differences than albendazole sulfoxide,” the agency said. “Albendazole is thus an inherently more accurate and reliable indicator for bioequivalence than albendazole sulfoxide. Nonetheless, if an ANDA applicant were to show that it is not possible to measure albendazole accurately or reliably in plasma as you claim, we would consider a statistical comparison of albendazole sulfoxide’s concentration-time profile data... as the basis for a demonstration of bioquivalence.”