ABSTRACT
Terahertz pulsed imaging (TPI) and near infrared (NIR) imaging were used to non-destructively monitor the coating process of film-coated tablets. Samples that were taken from a pan coater at different time points were analyzed by both methods. TPI provided coating thickness maps over the whole surface of the tablets, determining the thickness of the coating at each point of the sample surface in mum, this way also giving information about the coating uniformity. The growth of the coating during the coating process was shown. NIR imaging did not provide direct thickness values, but by different absorbance values, inter- and intra-tablet differences were shown. Thus, coating thickness information was also obtained in a way that different tablets could be compared. The growth of the coating layer during the process was shown as well. Both methods provided comparable results; and they were able to detect small defects in the coating. With TPI, the whole tablet surface could be scanned; with NIR imaging information about the tablet ends at the center-band was not obtained due to the strong curvature. NIR imaging proved to be better at thinner coating layers and had a higher spatial resolution whereas TPI had the clear advantage that it provided direct thickness values.
Subject(s)
Pharmaceutical Preparations/chemistry , Spectroscopy, Near-Infrared/methods , Tablets, Enteric-Coated/chemistry , Tablets, Enteric-Coated/standards , Technology, Pharmaceutical/methods , Terahertz Imaging/methods , Chemistry, Pharmaceutical/methods , Drug Compounding , Quality Control , Surface PropertiesABSTRACT
Near-infrared spectroscopy (NIRS) is a fast and non-destructive analytical method. Associated with chemometrics, it becomes a powerful tool for the pharmaceutical industry. Indeed, NIRS is suitable for analysis of solid, liquid and biotechnological pharmaceutical forms. Moreover, NIRS can be implemented during pharmaceutical development, in production for process monitoring or in quality control laboratories. This review focuses on chemometric techniques and pharmaceutical NIRS applications. The following topics are covered: qualitative analyses, quantitative methods and on-line applications. Theoretical and practical aspects are described with pharmaceutical examples of NIRS applications.
