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AAPS PharmSciTech. 2005 March; 6(1): E127–E136.
Published online 2005 September 20. doi:  10.1208/pt060120
PMCID: PMC2750421

Quantitative analysis of film coating in a pan coater based on in-line sensor measurements


A method was developed that enables in-line analysis of film coating thickness on tablets during a pan coating operation. Real-time measurements were made using a diffusereflectance near-infrared (NIR) probe positioned inside the pan during the coating operation. Real-time spectra of replicate batches were used for modeling film growth. Univariate analysis provided a simple method for in-line monitoring of the coating process using NIR data. An empirical geometric 2-vector volumetric growth model was developed, which accounts for differential growth on the face and band regions of biconvex tablets. The thickness of the film coat was determined by monitoring the decrease of absorption bands characteristic of a component of the tablet core and monitoring the increase of bands characteristic of a component in the coating material. There was good correlation between values estimated from the NIR data and the measured tablet volumetric growth. In-line measurements allow the coating process to be stopped when a predetermined tablet coating thickness is achieved.

Keywords: monitoring, modeling, prediction, filmcoating, NIR, diffuse reflectance

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
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