Friday, 26 April 2013

Hardness and density distributions of pharmaceutical tablets measured by terahertz pulsed imaging

Journal of Pharmaceutical Sciences
22 Apr 2013; +Wiley Textbooks
DOI: 10.1002/jps.23560

Authors: Robert K. May1,4, Ke Su1, Lianghao Han2, Shuncong Zhong3, James A. Elliott2, Lynn F. Gladden1, Mike Evans4, Yaochun Shen3, J. Axel Zeitler1
1. Department of Chemical Engineering and Biotechnology,+Cambridge University Press Education, Cambridge CB2 3RA, UK
2. Department of Materials Science and Metallurgy, +Cambridge University Press Education, Cambridge CB2 3QZ, UK
3. Department of Electrical Engineering and Electronics, +University of Liverpool, Liverpool L69 3GJ, UK
4. +TeraView Ltd., St John’s Innovation Park, Cambridge, CB4 0WS, UK


We present terahertz pulsed imaging (TPI) as a novel tool to quantify the hardness and surface density distribution of pharmaceutical tablets. Good agreement between the surface refractive index (SRI) measured by TPI and the crushing force measured from diametral compression tests was found using a set of tablets that were compacted at various compression forces. We also found a strong correlation between TPI results and tablet bulk density, and how these relate to tablet hardness. Numerical simulations of tablet surface density distribution by finite element analysis exhibit excellent agreement with the TPI measured SRI maps. These results show that TPI has an advantage over traditional diametral compression and is more suitable for nondestructive hardness and density distribution monitoring and control of pharmaceutical manufacturing processes. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci

...Terahertz pulsed imaging reflection measurements of sample tablets were acquired using a TPI Imaga 2000 (TeraView Ltd., Cambridge, UK). A detailed description of the measurement technique was presented earlier. The system has a useful spectral range of 60GHz to 3 THz, corresponding to a wavelength range of 0.09–5mm...

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