Powder Testing Techniques for QbD

Quality by Design, the new way of working enshrined in guidance from the FDA, raises the profile of pharmaceutical manufacturing and process development. More specifically it demands the detailed consideration of
processing issues during the earlier stages of development. This poses the question of how best to inject the necessary expertise from the outset. Analytical tools that ease communication across the traditional
formulation/process development/production boundaries can help.

Regulatory guidance for the pharmaceutical industry, issued over the last decade, has focused on reducing the risk of making and releasing out-of-specification product. Quality by Design, a major theme, can be described as the knowledgeled development of processes and manufacturing practice that robustly and routinely deliver product to meet a specification defined on the basis of clinical efficacy. The Process Analytical Technology (PAT) initiative on the other hand places emphasis on the greater use of suitable analytical techniques to monitor and control processes more effectively. The ultimate aim of the regulatory advice is to transform manufacture away from inefficient batch production towards the higher efficiency methods exemplified by the chemical industry.

QbD focuses attention on the relationship between the product, process development and manufacturing. It is not mandatory but holds out the promise of a lighter regulatory touch. Equally important QbD has the potential to tackle some tough industry challenges: low manufacturing efficiency; competition from the generics market; time to market; and an overly heavy reliance on post-production testing. In combination these are powerful motivating factors for implementation.

It is hard to argue against the more holistic, knowledge-led strategies outlined by QbD but there remain concerns about how to proceed. The need for process-related expertise at an earlier stage of development suggests new ways of working, possibly with different skill bases and/or discipline sets. Breaking down the sequential workflow of conventional development, and the traditional barriers between formulators, process designers and
manufacturing, will ensure that all can contribute, easing the burden inherent in knowing more, at an earlier stage.

Powder processing is a core activity within the industry and poses a unique set of challenges. Measuring powders in ways that relate to their in-process behaviour is especially difficult, but essential when getting to grips with QbD. An understanding of the links between formulation properties, equipment choice and setup, and manufacturing practice is vital for truly optimal processing. Recent developments in powder testing have a role to play and can smooth the path through to long-term efficient manufacture.