title: Multispectral UV Imaging for Determination of the Tablet Coating Thickness.
abstract: 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.
authors.affiliation: Division of Pharmaceutical Technology, Department of Chemistry, University of Hamburg, Bundesstraße 45, Hamburg 20146, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Novikova
authors.affiliation: Department of Applied Mathematics and Computer Science, Technical University of Denmark, Richard Petersens Plads Building 321, Lyngby 2800, Denmark.
authors.forename: Jens M
authors.initials: JM
authors.lastname: Carstensen
authors.affiliation: Department of Chemical Engineering, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA, UK.
authors.forename: J Axel
authors.initials: JA
authors.lastname: Zeitler
authors.affiliation: Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen 2100, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rades
authors.affiliation: Division of Pharmaceutical Technology, Department of Chemistry, University of Hamburg, Bundesstraße 45, Hamburg 20146, Germany. Electronic address: claudia.leopold@uni-hamburg.de.
authors.forename: Claudia S
authors.initials: CS
authors.lastname: Leopold
mesh_terms: D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000295:instrumentation; D004339:Drug Compounding; D004867:Equipment Design; D005079:Excipients / Q000737:chemistry; D061848:Optical Imaging / Q000295:instrumentation*; D011109:Polymethacrylic Acids / Q000737:chemistry*; D011786:Quality Control; D013499:Surface Properties; D013607:Tablets / Q000737:chemistry*; D055069:Terahertz Imaging; D014466:Ultraviolet Rays
chemical_list: D005079:Excipients; D011109:Polymethacrylic Acids; D013607:Tablets; C038300:methylmethacrylate-methacrylic acid copolymer; C013517:ethyl cellulose; D002482:Cellulose
keywords: PLS; UV imaging; coating thickness; multivariate data analysis; tablets; terahertz pulsed imaging