Pharmaceutical tablet hardness measurements with thz pulsed imaging

We present the results of terahertz pulsed imaging (TPI) experiments to measure the `hardness´ of pharmaceutical solid dosage forms (tablets) compacted at various compression forces. Results of TPI measurements are compared to those from diametric compression tests as well as finite element analysis (FEA) simulations of density distributions on the surface of the tablet. In both cases strong correlation with TPI results was found. In particular, radially symmetric spatial distributions in tablet density due to the shape of the punch used in tablet manufacture were observed. The results of these experiments show that TPI is suitable for non-destructive monitoring and control of pharmaceutical manufacturing processes.