Blend uniformity analysis: validation and in-process testing. Technical Report No. 25. PDA (Parenteral Drug association).

Journal of pharmaceutical science and technolog... 51 Suppl 3:i (1997) PMID 9448437

One of the most challenging problems confronting oral solid dosage form manufacturers today is the difficulty in applying scientifically valid methods to blend uniformity validation. The Wolin decision in U.S. v. Barr Laboratories caused the FDA to reexamine and modify its policies on blend uniformity and sampling techniques. The resulting policies are predicated on the assumption that current technology provides a means to consistently collect minute representative samples from much larger static powder blends. A comprehensive review of the scientific literature indicates that current sampling technology is plagued by a propensity for sampling bias. This limitation is particularly troublesome to the pharmaceutical industry which must then hold these samples to very high standards. In response to these concerns the PDA Solid Dosage Process Validation Committee has reviewed approaches to blend uniformity analysis. This technical report provides: a method to determine the appropriate sample size for each product, a holistic approach for establishing meaningful acceptance criteria, a discussion on the use of proper analytical techniques and recommendations for conducting investigations for out-of-specification results.