PREFORMULATION STUDY OF PHARMACEUTICAL EXCIPIENTS: A WATER ACTIVITY PERSPECTIVE

Abstract

Water plays a critical role in pharmaceutical processing, as several manufacturing unit operations such as wet granulation, spray drying and film coating often require water. While there have been considerable literature reports on the effect of water-excipient interactions on the performance and stability of dosage forms, to date, the inter-variable relationships amongst water activity, moisture content and end product quality have not been thoroughly explored. This research work attempted to use water activity measurements to provide an understanding of the lability of water molecules and their ability to interact with the active and co-formulated constituents. Overall, the findings of this research work can aid formulation scientists to understand the functionality of excipients in the presence of moisture and therefore make informed choices when selecting excipients for a tablet formulation, especially in terms of their water sorption capacities in environments of differing relative humidities.