(586n) In-Line Monitoring of a Fluid-Bed Coating Process With Optical Coherence Tomography

In-line monitoring of a fluid-bed coating process with optical coherence tomography

Stephan Sacher¹, Daniel Markl¹, Günther Hannesschläger², Michael Leitner², Johannes G. Khinast³

¹ Research Center Pharmaceutical Engineering GmbH, Inffeldgasse 13/2, 8010 Graz, Austria

² Research Center for Non-Destructive Testing GmbH, Science Park 2, Altenberger Strasse 69, 4040 Linz, Austria

³ Institute for Process and Particle Engineering, Graz University of Technology, Inffeldgasse 13/3, 8010 Graz Austria

Coating of tablets, pellets and granules is one of the most common unit operations in pharmaceutical industry. Uniformity and thickness of the coating layer are crucial for efficacy as well as for compliance. Therefore, not only because of different initiatives it is essential to monitor and control the coating process in-line.

Optical coherence tomography (OCT) features a contact-free non-destructive technique based on white light interferometry offering high resolution images of internal structures of solid materials. Independent on calibration models like e.g. spectroscopic methods, and small in space compared to terahertz, it represents an alternative process monitoring technique enabling to investigate coating thickness as well as coating homogeneity. Due to the fast acquisition rate it is even possible to measure single tablet or pellet parameters within a bulk of moving tablets.

In this study the applicability of OCT to monitor growth of coating in-line is validated. Therefore, an OCT system is integrated into a commercially available pilot-scale fluid-bed system. In a first step fluidized pellets with and without prior applied coating passing with high speed are measured. In addition in-line experiments with real-time monitoring of coating growth are performed. Results show that OCT is a suitable technique to measure coating thickness of even fast moving particles within pharmaceutical production processes.