Blend Uniformity and Content Uniformity (BUCU) Initiative

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In August 2013, the FDA announced the withdrawal of its draft guidance document for industry, Powder Blends and Finished Dosage Units – Stratified In-Process Dosage Unit Sampling and Assessment. The primary reason for the withdrawal of the draft guidance document was that Sections V and VII no longer represented the Agency’s current thinking.

At the same time, FDA stated that the USP <905> Uniformity of Dosage Units should not be applied for product release testing due to concerns that the results of the test did not provide sufficient assurance that future samples taken from the batch would also comply with the same acceptance criteria.

The withdrawal of the document and FDA’s lack of confidence in the results from USP <905> Uniformity of Dosage Units testing resulted in uncertainty for manufacturers, but also presented an opportunity for developing a modernized approach to enforcing the GMP requirements in this area.

BUCU Team Formed to Find Alternatives

ISPE sponsored a group of individuals from the FDA, industry, and academia, to discuss alternative approaches to assess Blend and Content Uniformity (BUCU), with a goal of publishing best practice for potential use in future guidance and policy.

The BUCU Team presented a series of talks during a session at the ISPE Annual Meeting in November 2013 covering the current issues associated with blend and content uniformity analysis, FDA concerns with current practices, and the importance of using statistically sound sampling plans and acceptance criteria.

From those discussions the BUCU Team drafted a two-part paper defining alternate approaches for the assessment of blend and content uniformity. The Team’s approach is scientifically justified, especially for products that use traditional analytical techniques to assess adequacy of powder mix and dosage unit uniformity, and addresses FDA’s primary concerns that led to the withdrawal of the draft guidance document.

For more information on the Blend Uniformity and Content Uniformity Initiative, please contact Carol Winfield, ISPE Director of Regulatory Operations, at


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