Institute of Photonics, University of Eastern Finland, P. O. Box 111, FI-80101 Joensuu, Finland.
Institute of Photonics, University of Eastern Finland, P. O. Box 111, FI-80101 Joensuu, Finland.
Int J Pharm. 2014 Apr 25;465(1-2):70-6. doi: 10.1016/j.ijpharm.2014.02.011. Epub 2014 Feb 12.
We report on the non-destructive quantification of the porosity of pharmaceutical compacts (microcrystalline cellulose tablets) by using both optical and terahertz techniques. For the full analysis of the porosity of pharmaceutical tablets, the results obtained in both cases have shown that optical and terahertz techniques are complementary. The intrinsic refractive index of microcrystalline cellulose was estimated using the effective refractive index obtained from the time delay of the THz pulse together with the Bruggeman model for effective media. Once this intrinsic refractive index is known, the unknown porosity of the tablet can be estimated with the aid of the measured effective refractive index as well as the thickness of the pharmaceutical tablet. The method was tested using a set of thirteen tablets having different porosities. It is shown that the error in the estimation of the unknown tablet's porosity is less than 1%. In addition, surface roughness was measured by using an optical interferometer and gloss by using a diffractive-optical-element based glossmeter. The measurement was achieved by scanning the tablets with a probe beam and detecting the reflected light. The surface roughness and gloss data show relatively good correlation with the porosities of the tablets.
我们报告了使用光学和太赫兹技术对药物压片（微晶纤维素片）的孔隙率进行无损定量的方法。为了全面分析药物片剂的孔隙率，两种情况下得到的结果都表明，光学和太赫兹技术是互补的。通过使用太赫兹脉冲的时间延迟获得的有效折射率以及有效介质的 Bruggeman 模型来估算微晶纤维素的固有折射率。一旦知道了这个固有折射率，就可以借助测量得到的有效折射率以及药物片剂的厚度来估算片剂的未知孔隙率。该方法使用了一组具有不同孔隙率的十三片片剂进行了测试。结果表明，对未知片剂孔隙率的估计误差小于 1%。此外，还使用光学干涉仪测量了表面粗糙度，使用基于衍射光学元件的光泽度计测量了光泽度。通过用探针光束扫描片剂并检测反射光来实现测量。表面粗糙度和光泽度数据与片剂的孔隙率具有很好的相关性。
