Linking powder to tablet stability: Length- and time-scale prediction of moisture sorption

Physical stability testing is crucial in pharmaceutical development, requiring a thorough understanding of how moisture interacts with materials to ensure tablet integrity and performance. This study explores how tablet porosity and the inclusion of swelling excipients influence moisture uptake and stability across different length and time scales, from particle-level interactions to tablet behaviour and from short-term moisture sorption using dynamic vapour sorption (DVS) to long-term storage effects. Two tablet formulations were tested: pure MCC and MCC-CCS (8%), each with four different porosities. A predictive framework was developed to estimate porosity changes in stored tablets by accounting for particle swelling. The study highlights rapid structural changes, including reductions in tensile strength, bulk density, and porosity, which occur mostly within the first day of storage. By linking powder and tablet DVS data and establishing correlations between DVS and real-storage data, this study provides a framework for predicting moisture sorption behaviour in tablets over time. This approach enhances the predictability of tablet stability, reducing the need for extensive long-term storage studies and enabling faster, more reliable stability assessments. Ultimately, these findings provide a stronger foundation for optimising stability testing and formulation performance.