This study presents the porosity and corresponding specific surface area evolution of pharmaceutical tablets vs. compaction pressure. A model based on quasi-chemical treatments and population balances is proposed to understand these evolutions. The main phenomena, namely fragmentation and plastic deformation, which occur in pharmaceutical powder compaction, are taken into account to explain the conjugate evolution of these macroscopic properties. These phenomena are quantified through the different parameters of the model. Experimental results on tablettose, saccharose and ketoprofen tablets show a fair agreement with theoretical results, and allow us to classify the fragmentation and the plastic deformation abilities of the products.

The purpose of this work consists in following physical property variations in relation with geometrical textural parameters during pharmaceutical component compaction. Models are developed to explain porosity variations of granular media submitted to increasing uniaxial pressure. These models are based on reaction mechanisms analogous to these presented in quasi chemical descriptions. Vacancy annihilation occurring when pressure increases is studied in two cases (with or without internal grain porosity). Reaction mechanisms describing different granular rearrangement phenomena are proposed. The behaviour of pure compounds as well as that of binary mixtures are studied from a theoretical point of view, and the model results proposed in this case are compared with the ones derived from experiments. In particular mixtures of one excipient, lactose, and one active principle, ketoprofen, are analysed in order to estimate porosity evolution of such mixtures, and determine mixture effects on tablet properties. The prediction limits which could be done by mixture models giving an expected behaviour starting from pure components only are discussed.