A quantitative comparison of in-line coating thickness distributions obtained from a pharmaceutical tablet mixing process using discrete element method and terahertz pulsed imaging



Pei, Chunlei, Lin, Hungyen, Markl, Daniel, Shen, Yao-Chun ORCID: 0000-0002-8915-1993, Zeitler, J Axel and Elliott, James A
(2018) A quantitative comparison of in-line coating thickness distributions obtained from a pharmaceutical tablet mixing process using discrete element method and terahertz pulsed imaging. CHEMICAL ENGINEERING SCIENCE, 192. pp. 34-45.

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Abstract

The application of terahertz pulsed imaging (TPI) in an in-line configuration to monitor the coating thickness distribution of pharmaceutical tablets has the potential to improve the performance and quality of the spray coating process. In this study, an in-line TPI method is used to measure coating thickness distributions on pre-coated tablets during mixing in a rotating pan, and compared with results obtained numerically using the discrete element method (DEM) combined with a ray-tracing technique. The hit rates (i.e. the number of successful coating thickness measurements per minute) obtained from both terahertz in-line experiments and the DEM/ray-tracing simulations are in good agreement, and both increase with the number of baffles in the mixing pan. We demonstrate that the coating thickness variability as determined from the ray-traced data and the terahertz in-line measurements represents mainly the intra-tablet variability due to relatively uniform mean coating thickness across tablets. The mean coating thickness of the ray-traced data from the numerical simulations agrees well with the mean coating thickness as determined by the off-line TPI measurements. The mean coating thickness of in-line TPI measurements is slightly higher than that of the off-line measurements. This discrepancy can be corrected based on the cap-to-band surface area ratio of the tablet and the cap-to-band sampling ratio obtained from ray-tracing simulations: the corrected mean coating thickness of the in-line TPI measurements shows a better agreement with that of the off-line measurements.

Item Type: Article
Additional Information: publisher: Elsevier articletitle: A quantitative comparison of in-line coating thickness distributions obtained from a pharmaceutical tablet mixing process using discrete element method and terahertz pulsed imaging journaltitle: Chemical Engineering Science articlelink: https://doi.org/10.1016/j.ces.2018.06.045 content_type: article copyright: © 2018 Published by Elsevier Ltd.
Uncontrolled Keywords: Terahertz in-line sensing, Terahertz pulsed imaging, Coating thickness variability, Discrete element method, Pharmaceutical coating
Depositing User: Symplectic Admin
Date Deposited: 14 Nov 2018 10:30
Last Modified: 19 Jan 2023 01:13
DOI: 10.1016/j.ces.2018.06.045
Open Access URL: https://www.repository.cam.ac.uk/handle/1810/28410...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3028721