Maurer Lene, Leuenberger Hans
F. Hoffmann-La Roche Ltd., Grenzacherstrasse, 4070 Basel, Switzerland.
Int J Pharm. 2009 Mar 31;370(1-2):8-16. doi: 10.1016/j.ijpharm.2008.11.011. Epub 2008 Nov 25.
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.
太赫兹脉冲成像（TPI）和近红外（NIR）成像被用于无损监测薄膜包衣片的包衣过程。从锅式包衣机在不同时间点采集的样品用这两种方法进行分析。TPI提供了片剂整个表面的包衣厚度图，以微米为单位确定样品表面每个点的包衣厚度，这样也给出了关于包衣均匀性的信息。展示了包衣过程中包衣的生长情况。近红外成像没有提供直接的厚度值，但通过不同的吸光度值，显示了片间和片内的差异。因此，也以一种可以比较不同片剂的方式获得了包衣厚度信息。还展示了该过程中包衣层的生长情况。两种方法提供了可比的结果；并且它们能够检测到包衣中的小缺陷。使用TPI，可以扫描整个片剂表面；使用近红外成像，由于强烈的曲率，无法获得关于片剂中心带两端的信息。近红外成像在较薄包衣层时表现更好，并且具有更高的空间分辨率，而TPI具有提供直接厚度值的明显优势。
