Physical and thermal characterisation of Precirol and Compritol as lipophilic glycerides used for the preparation of controlled-release matrix pellets.

Physical and thermal properties of Compritol and Precirol as potential lipophilic binders in melt pelletisation process for the preparation of sustained-release matrix pellets were evaluated in this study. Experimental measurements were carried out using X-ray diffractometry, differential scanning calorimetry (DSC), hot-stage microscopy (HSM) and rheological measurements. These studies have shown that the lipophilic binders may present a relatively complex behaviour depending on the sample treatment (untreated, freshly solidified, aged samples). DSC and HSM methods have shown the presence of polymorphism for Precirol. Moreover, both untreated and fresh solidified Precirol and Compritol samples present partially amorphous layered structure which slowly crystallise in time. The rate of crystallisation was found to be more rapid for Precirol, and highly dependent on the ageing conditions (storage temperature). Finally, the evaluation of the thermal and rheological properties of Precirol and Compritol mixtures have shown that the use of such mixtures, presenting well distinct melting properties, could be a very interesting tool for the preparation of high fatty binder content prolonged-release pellets in high shear mixers if the product temperature is carefully controlled (between 45 and 50 degrees C) during the pelletisation process.