(565g) Progress in Industrial Implementation of Optical Coherence Tomography (OCT) for Real-Time Evaluation of Pharmaceutical Coating Processes

The coating thickness of modified release coatings, enteric release coatings or coatings containing active pharmaceutical ingredients (APIs) is of biopharmaceutical importance. For modified release coating the coating thickness directly affects the dissolution profile. Thus, methods for in-line measurement of coating thickness can bring significant benefits with regards to end-point determination and monitoring of process trajectories.

Typical established methods to measure the coating thickness are weight and diameter gain of a limited number of drawn samples. In-line measurements mainly focus on spectroscopic techniques (NIR and Raman) or particle size distribution (PSD) analysis of beads. An emerging technology to measure the coating thickness is optical coherence tomography (OCT). OCT has several advantages compared to the state-of-the-art as it provides a direct measurement of coating thickness, only based on refractive index, not depending on chemometrics or on PSD statistical analysis. Additionally, OCT can deliver information of mean coating thickness and uniquely its variation within single samples and between the samples of a batch.

Optical coherence tomography has been presented as a proof-of-concept prototype at several conferences and papers are dealing with the data evaluation algorithms. This talk will focus on the application of an OCT system ready for industrial implementation in drum coating of tablets and fluid-bed coating of beads. Challenges in an industrial setting are for example the eccentricity of the drum, compensation of dispersion by thick process windows and the vast variation of coating materials, leading to different appearances of the OCT image.

The potential of OCT for monitoring and control of pharmaceutical coating processes is shown by in-line and at-line data for tablets and beads.

The authors would also like to acknowledge the contributions of Manuel Zettl, Philipp Jocham, Gregor Hauseder, Lukas Pichler and Michael Weissensteiner for experimental work and software development.