In-Line Film Coating Thickness Estimation of Minitablets in a Fluid-Bed Coating Equipment
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Film coating thickness of minitablets was estimated in-line during coating in a fluid-bed equipment by means of visual imaging. An existing, commercially available image acquisition system was used for image acquisition, while dedicated image analysis and data analysis methods were developed for this purpose. The methods were first tested against simulated minitablet’s images and after that examined on a laboratory-scale fluid-bed Wurster coating process. An observation window cleaning mechanism was developed for this purpose. Six batches of minitablets were coated in total, using two different dispersions, where for the second dispersion coating endpoint was determined based on the in-line measurement. Coating thickness estimates were calculated from the increasing size distributions of the minitablet’s major and minor lengths, assessed from the acquired images. Information on both the minitablet’s average band and average cap coating thicknesses was obtained. The in-line coating thickness estimates were compared to the coating thickness weight gain calculations and the optical microscope measurements as a reference method. Average band coating thickness estimate was found the most accurate in comparison to microscope measurements, with root mean square error of 1.30 μm. The window cleaning mechanism was crucial for the accuracy of the in-line measurements as was evident from the corresponding decrease of the root mean square error (9.52 μm, band coating thickness). The presented visual imaging approach exhibits accuracy of at least 2 μm and is not susceptible to coating formulation or color variations. It presents a promising alternative to other existing techniques for the in-line coating thickness estimation.
KEY WORDSminitablets fluid-bed coating film coating thickness visual imaging PATVIS APA
The authors would like to thank Lek Pharmaceuticals d.d. (Sandoz Development Center Slovenia) for generously providing the minitablet cores used in this study.
- 2.Mohd AH, Raghavendra RN, Sunil F. Mini-tablets technology: an overview. Am J PharmTech Res. 2012;2(2):128–50.Google Scholar
- 8.Bodea M, Tomuta Io, Leucuta S. Film coating preparation of metoprolol tartrate mini-tablets and in vitro drug release studies. Clujul Med. 2010;83(3):457–63.Google Scholar
- 12.Funaro C, Mondelli G, Passerini N, Albertini B. Minitablets coated in a solid-wall pan for theophylline sustained-release capsules. Pharm Technol Eur. 2010;11:S38–42.Google Scholar
- 17.Cole G, Hogan J, Aulton M. Pharmaceutical coating technology. In: Taylor & Francis Ltd; 1995.Google Scholar
- 27.Mozina M, Tomaževič D, Leben S, Pernuš F, Likar B. Digital imaging as a process analytical technology tool for fluid-bed pellet coating process. Eur J Pharm Sci Off J Eur Fed Pharm Sci. 2010;41(1):156–62.Google Scholar
- 29.Forsyth DA, Ponce J. Computer vision: a modern approach. 1st ed. Orlando: Prentice Hall; 2002.Google Scholar
- 30.Fitzgibbon AW, Fisher RB. A buyer’s guide to conic fitting. In: Proceedings of the 6th British Conference on Machine Vision (Vol 2). Surrey: BMVA Press; 1995. p. 513–22.Google Scholar
- 31.Martin L, Deng H, Missaghi S, Farrell P, Rajabi-Siahboomi A. Investigation of cellulose acetate polymer viscosity and coating solution concentration on performance of push-pull osmotic pump (PPOP) tablets. In Québec City, Canada; 2012. (poster reprint CRS 2012; vol. 2012).Google Scholar