Multispectral UV Imaging for Determination of the Tablet Coating Thickness

• Published in: Journal of pharmaceutical sciences Vol. 106; no. 6; pp. 1560 - 1569
• Main Authors: Novikova, Anna, Carstensen, Jens M., Zeitler, J. Axel, Rades, Thomas, Leopold, Claudia S.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2017
• Subjects: Cellulose - analogs & derivatives; Cellulose - chemistry; Chemistry, Pharmaceutical - instrumentation; coating thickness; Drug Compounding; Equipment Design; Excipients - chemistry; multivariate data analysis; Optical Imaging - instrumentation; PLS; Polymethacrylic Acids - chemistry; Quality Control; Surface Properties; tablets; Tablets - chemistry; Terahertz Imaging; terahertz pulsed imaging; Ultraviolet Rays; UV imaging; terahertz pulsed imaging; UV imaging; RMSEP; LV; MCC; TPI; RMSEC; RMSECV; PLS; multivariate data analysis; Theo; tablets; coating thickness; HPMC
• ISSN: 0022-3549; 1520-6017
• DOI: 10.1016/j.xphs.2017.02.016

The applicability of off-line multispectral UV imaging in combination with multivariate data analysis was investigated to determine the coating thickness and its distribution on the tablet surface during lab-scale coating. The UV imaging results were compared with the weight gain measured for each individual tablet and the corresponding coating thickness and its distribution measured by terahertz pulsed imaging (TPI). Three different tablet formulations were investigated, 2 of which contained UV-active tablet cores. Three coating formulations were applied: Aquacoat® ECD (a mainly translucent coating) and Eudragit® NE (a turbid coating containing solid particles). It was shown that UV imaging is a fast and nondestructive method to predict individual tablet weight gain as well as coating thickness. The coating thickness distribution profiles determined by UV imaging correlated to the results of the TPI measurements. UV imaging appears to hold a significant potential as a process analytical technology tool for determination of the tablet coating thickness and its distribution resulting from its high measurement speed, high molar absorptivity, and a high scattering coefficient, in addition to relatively low costs.