Transient Temperature Monitoring of Pharmaceutical Tablets During Compaction Using Infrared Thermography

Manufacturing of pharmaceutical tablets from powders is always accompanied by the conversion of irreversible mechanical work of compaction into heat. The heat is generated due to friction between powder particles, particles and the die wall, plastic deformation of particles, bonding, and other irreversible processes. The resulting temperature increase potentially might have significant effects on a tablet's mechanical properties, disintegration time, and drug release. In the present work, we show that using infrared thermography as a nondestructive and noncontact process analytical technology (PAT) tool to measure the tablet's rate of cooling, in contrast to the temperature evolution, can be directly related to the tablet's thermal diffusivity. Results show the potential capabilities of this technique to discriminate and toward predicting tensile strength of tablets between same formulations produced at same compaction force but experienced different process shear conditions. Correlation of the tablet's tensile strength, relative density, and rate of cooling at regular regime with respect to different process shear is also discussed.