INTRODUCTION
In a quality by design (QbD) environment knowledge and understanding of raw material critical quality attributes (CQAs) are essential [1]. Excipient variability is an important consideration particularly when blended with challenging APIs where manufacturing may occur close to the edge of failure, i.e. close to the acceptance limits for critical quality attributes. In such cases small variations in an excipients attribute could possibly impact the end product quality, even if the variation is within the excipient’s certificate of analysis release specifications. Continuous process improvement, continuous manufacturing and regulatory requirements for improved process understanding as covered by ICH Q10 [2] drive a need to understand the impact of excipient variability on finished product performance.