INFLUENCE OF SIZE POLYDISPERSITY ON DRUG RELEASE FROM COATED PELLETS

In this study, a previously demonstrated model for monodispersed pellets is extended to the case of polydispersed systems. To validate the model, ketoprofen pellets prepared using the extrusion-spheronisation process were coated with an acrylic membrane (Eudragit(R) RL and triacetin). The effect of pellet size polydispersity on drug release was investigated by screening the spherical matrices before coating. Dissolution testing was performed on each fraction and pellet batch before screening; it was possible to predict the release kinetics of the latter to a good approximation. Next the different fractions were separately coated with a polymeric membrane of nearly identical thickness and their drug release kinetics were interpreted according to the investigated model. The polydispersed system was also coated and screened. The results from the interpretation of the drug release kinetics of each fraction showed that there was apparently no significant influence of pellet size on the coating thickness.