title: Hardness and density distributions of pharmaceutical tablets measured by terahertz pulsed imaging.
abstract: 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.
authors.affiliation: Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB2 3RA, UK.
authors.forename: Robert K
authors.initials: RK
authors.lastname: May
authors.forename: Ke
authors.initials: K
authors.lastname: Su
authors.forename: Lianghao
authors.initials: L
authors.lastname: Han
authors.forename: Shuncong
authors.initials: S
authors.lastname: Zhong
authors.forename: James A
authors.initials: JA
authors.lastname: Elliott
authors.forename: Lynn F
authors.initials: LF
authors.lastname: Gladden
authors.forename: Mike
authors.initials: M
authors.lastname: Evans
authors.forename: Yaochun
authors.initials: Y
authors.lastname: Shen
authors.forename: J Axel
authors.initials: JA
authors.lastname: Zeitler
mesh_terms: D004339:Drug Compounding; D020342:Finite Element Analysis; D006244:Hardness; D012031:Refractometry; D013499:Surface Properties; D013607:Tablets / Q000737:chemistry*; D055069:Terahertz Imaging
chemical_list: D013607:Tablets