The use of stratefied sampling of blend and dosage units to demonstrate adequacy of mix for powder blends.

In response to concerns expressed by applicants regarding inconsistent policies in establishing blend uniformity acceptance criteria to demonstrate adequacy of mix, the FDA Office of Generic Drugs (OGD) issued the draft document Guidance for Industry, ANDAs: Blend Uniformity Analysis (August 1999). Both generic and innovator pharmaceutical companies raised a number of concerns following the publication of this document. As a result, the Product Quality Research Institute (PQRI) Blend Uniformity Working Group (BUWG) was established in February 2000.