Preparation of granular systems by extrusion/spheronization: A twin product/process approach

The extrusion/spheronization technique makes a notable contribution to the existing range of pharmaceutical forms, especially in the area of oral controlled-release product. Analysis of this technique leads the authors to make a parallel study of the influences of the aspects linked to formulation (water content) and to processing used (extruder screw speed) with the aim of optimizing the product quality. Textural variables, porosity, saturation degree and water content were monitored throughout the elaboration process. The kneading operation brings the material to a state in which porosity is linked to water content. The extrusion operation densities the material to saturation point, while spheronization is simply a shaping process which maintains the hygrotextural state. Also emphasized is the presence of solid/liquid ratios optimizing pellet quality independently of the operating variables. In parallel to this, a range of water content for which the influence of the process parameter is relevant is identified.