Salix Wants Restrictions on Xifaxan ANDAs

Salix Pharmaceuticals is petitioning FDA not to approve an ANDA citing any strength of its Xifaxan (rifaximin) as the reference-listed drug unless it conforms with an extensive series of conditions submitted by Salix. The company says that any ANDA that references either strength or any indication of Xifaxan as the reference-listed drug should meet these criteria: characterization studies demonstrating that the proposed generic’s active ingredient is identical in rifaximin polymorph profile to that of the Xifaxan active ingredient ,and specified bioequivalence and in vitro dissolution tests with outcomes specified by Salix.

The company also asks that FDA revise its draft guidance on rifaximin to incorporate its criteria at a minimum.

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