Excipient variability and its impact on dosage form functionality.

Pharmaceutical excipients are essential components of most modern dosage forms. Although defined as pharmacologically inert, excipients can be thought of as the true enablers of drug product performance. Unintentional variability in the properties of the excipients may be unavoidable, albeit minimizable. The variability may originate from the source, the excipient-manufacturing process, or during the manufacturing of dosage forms. Excipient variability may have a range of influences on their functionality and performance in the dosage form. A better understanding of these influences on the critical quality attributes of the final product is of prime importance. Modern analytical tools provide a significant assistance in characterizing excipient variability to achieve this understanding. The principles and concepts of Quality-by-Design, process analytical technology, and design space, provide a holistic risk-based approach toward manufacture and application of excipients in pharmaceutical formulations. The International Pharmaceutical Excipients Council (IPEC) has developed guidelines for proper selection, use, and evaluation of excipients in pharmaceutical products.