Evaluation of time-temperature parameter effects on the structural characteristics of films obtained by aqueous polymeric dispersions

Pellet cores, containing d-indobufen as the active principle, were prepared by the extrusion-spheronization process and coated with an aqueous polymeric dispersion using Wurster bottom-spray equipment. The present study investigated factors affecting the film properties, such as the product temperature during the coating process and the effects of the thermal postcoating treatment (curing phase), carried out in different drying conditions. The experimental results, in terms of drug release control, confirm that the properties of the film coating depend on the substrate temperature, which directly influences the coalescence process of the polymeric dispersion. Moreover, along with time and temperature of the drying phase, the type of equipment used affects the performance of the film coating dosage form. In particular, using the fluidized bed at a high temperature for a short time produced a film coating structure that seemed to remain unchanged after storage.