Rapid Assessment of Tablet Film Coating Quality by Multispectral UV Imaging

Abstract

Abstract. Chemical imaging techniques are beneficial for control of tablet coating layer quality as they provide spectral and spatial information and allow characterization of various types of coating defects. The purpose of this study was to assess the applicability of multispectral UV imaging for assessment of the coating layer quality of tablets. UV images were used to detect, characterize, and localize coating layer defects such as chipped parts, inhomogeneities, and cracks, as well as to evaluate the coating surface texture. Acetylsalicylic acid tablets were prepared on a rotary tablet press and coated with a polyvinyl alcohol-polyethylene glycol graft copolymer using a pan coater. It was demonstrated that the coating intactness can be assessed accurately and fast by UV imaging. The different types of coating defects could be differentiated and localized based on multivariate image analysis and Soft Independent Modeling by Class Analogy applied to the UV images. Tablets with inhomogeneous texture of the coating could be identified and distinguished from those with a homogeneous surface texture. Consequently, UV imaging was shown to be well-suited for monitoring of the tablet coating layer quality. UV imaging is a promising technique for fast quality control of the tablet coating because of the high data acquisition speed and its nondestructive analytical nature.

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“…The control system monitors the machine while the automation ensuing batch-to-batch quality compliance and consistency 14 . Modern coaters use computer software designed to make the process more automate and efficient (from charging to discharging) and/or to monitor the number of parameters such as the spin-rate of the drum, coating time 44 , substrate surface flow velocity 17,45 , spray-rate 24 , flow rate and temperature of inlet air 24 , process humidity 46,47 , coating weight gain 42,48 , coating attributes 49,52 and many more 16,23,53,55 . In addition, computerization can store process instructions or recipes that produce specific results 12 .…”

Characterization of the coating and tablet core roughness by means of 3D optical coherence tomography

“…Surface roughness was previously investigated using stylus instruments (Rowe, 1979;1978), optical microscopy (Seitavuopio et al, 2003), laser profilometer (Seitavuopio et al, 2003), scanning electron microscopy (SEM) (Riippi et al, 1998;Seitavuopio et al, 2006), atomic force microscopy (AFM) (Seitavuopio et al, 2003) and UV imaging (Klukkert et al, 2015). However, these techniques do not allow the characterization of the roughness of the uncoated, and of the coated, tablet simultaneously at the same position.…”