Spatially-resolved quantification of erosion and swelling of tablets in a paddle dissolution apparatus with integrated optical coherence tomography.

Disintegration and dissolution play a key role in drug release from oral immediate-release products. An improved understanding of these processes, the impact of process parameters and the critical material attributes are required to develop robust formulations and manufacturing processes. This study demonstrates an in-situ disintegration and dissolution monitoring system capable of capturing quantitative swelling and erosion data in a paddle dissolution apparatus. The system utilises optical coherence tomography integrated with a bathless direct heating vessel and overhead stirrer. A bespoke sample holder was developed to keep the tablets in place and allow swelling and erosion to be captured. Tablet swelling and erosion were captured and quantified for different paracetamol and ibuprofen formulations. For slowly disintegrating tablets (no disintegrant) consistent swelling that correlated with drug release was observed, with 10 % porosity tablets swelling up to 1000 µm in 2 min while 20 % porosity tablets swelled up to 1900 µm. For rapidly disintegrating tablets, phases of swelling and erosion dominated the disintegration process, the length and extent of which increased with increasing porosity. This new system has multiple academic and industrial applications, including identifying performance-controlling disintegration mechanisms in problem formulations and developing a deeper understanding of stability study results.