Real-time monitoring and characterization of thin film drug delivery systems using optical coherence tomography

The development of drug delivery systems demands close attention to product quality and consistency of quality attributes to guarantee reproducibility in fabrication, performance and therapeutic effectiveness. While some methods exist for monitoring in-line manufacturing, these methods are limited in terms of spatial resolution or depth penetration, which can lead to inconsistent characterization. Furthermore, conventional static characterization methods often lack the ability to monitor time-dependent changes within drug delivery systems. This limits their effectiveness in capturing dynamic processes such as swelling, disintegration, and drug release, underscoring the need for advanced techniques that offer reliable, high-resolution, and depth-specific insights into these mechanisms over time. Optical coherence tomography (OCT) is a non-invasive, high-resolution imaging technique which shows promise for comprehensive characterization of structural and dynamic characterization of drug delivery systems. In this study, we explore applications of OCT to structural and dynamic characterization of thin film drug delivery systems. We demonstrate that OCT can be used to non-destructively monitor the spatial variation of the refractive index and thickness of thin films, providing crucial feedback for quality control and ensuring standardized doses in individual film units. Further, we demonstrate that OCT can be used to monitor the dissolution dynamics, enabling characterization of time-controlled release mechanisms. These results suggest that OCT has the potential to enhance thin-film characterization by enabling more precise monitoring of critical quality attributes, which can contribute to improved manufacturing consistency and better control over the uniformity of the dose in each film unit.