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# Petition Partially Granted for Linzess Bioequivalence
- URL: https://www.fdaweb.com/petition-partially-granted-for-linzess-bioequivalence/
- Published: 2019-01-02T12:00:00.000Z
- Updated: 2026-09-15T00:51:42.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5143055

FDA has partially granted an Allergan petition (submitted by Hyman Phelps & McNamara) seeking added bioequivalence assurances for irritable bowel syndrome drug Linzess (linaclotide). The petition urged the agency to require ANDA applicants seeking approval for generic Linzess to “demonstrate bioequivalence to Linzess in a clinical endpoint bioequivalence study.”

In a just-posted [response letter](https://www.regulations.gov/contentStreamer?documentId=FDA-2016-P-1962-0006&attachmentNumber=1&contentType=pdf&ref=fdaweb.com), FDA declined to require all Linzess ANDA applicants to conduct a comparative clinical endpoint study because dissolution testing may be adequate for some applicants. The agency said the petition is granted in part because a draft bioquivalence guidance proposes that such trials could be appropriate in some cases.