Stratified sampling of blend

The Use of Stratified Sampling of Blend and Dosage Units to Demonstrate Adequacy of Mix for Powder Blends, Blend Uniformity Working Group of Product Quality Research Institute (PQRI) available at PQRI Website (http //www. pqri.org). 

Prepare a summary of the data and analysis used to correlate the stratified sampling locations with significant events in the blending process. 

Segregation of During compression, Remaining blend in Take stratified samples... 

If the FDA chooses to follow the stratified sampling recommendation of the PQRI, blend uniformity testing and the large problem of sampling may soon become history. Until then, however, guidelines should be followed at all times, awareness should be raised to minimize errors, and the importance of sampling should not be underestimated. Testing must be carried out frequently to ensure that each blend reaches the standards set. 

Stratified sampling is more likely to reveal uniformity problems than if less discriminating methods were used. A tool was developed and published (84) to aid formulation and process development scientists in troubleshooting content uniformity problems. The approach is that if stratified sample results were available for blend and/or product samples, the data will point the troubleshooter towards potential causes for uniformity problems in rank order of likelihood. Once potential root causes have been identified, areas for further investigation and possible corrective actions are also presented. 

Draft Guidance for Industry Powder blends and finished dosage units—stratified in-process dosage unit sampling and assessment. U.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research (CDER), October 2003. 

Six basic trends commonly observed for product uniformity and blend samples are described, based on stratified nested sampling. The described trends are based on tendencies of the mean, between-location variance, and within-location variance. The six trends are ... 

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