Identifying CQAs And CPPs: Powder Measurement For QbD

By Tim Freeman, Freeman Technology

Implementing QbD calls for identification of both critical quality attributes (CQAs) and critical process parameters (CPPs). CQAs are those that impact key aspects of product performance, such as safety, efficacy, and stability. CPPs are the process variables that control CQAs during manufacture. It is clearly essential to accurately define and control both sets of variables, but it also requires detailed knowledge of the process and the product. Acquiring this information can present a challenge, especially for particulate systems; however, modern multifaceted powder characterization can help by providing highly relevant data in a cost-and time-effective way.

Consider the requirements for powder characterization imposed by adopting QbD in the development of a particulate product. Formulation demands definition of the powder properties that control product performance (CQAs) and determination of associated specifications for release. Process designers, on the other hand, need to understand how powder characteristics will affect in-plant behavior, in order to ensure compatibility between equipment and material, and develop a process that consistently delivers in-spec product. An important part of this is setting appropriate specifications for any powder feeds to the plant, since batch-to-batch variation may affect processability and/or product quality.