A burst drug release caused by imperfection of polymeric film-coated microparticles prepared by a fluidized bed coater.

The aim of this study was to investigate the drug release from microparticles coated with various polymeric films. Ibuprofen-loaded microparticles with diameter of 250 and 300 microm were prepared by a fluidized bed granulator. Five polymers were used as coating materials, i.e., ethylene vinyl acetate, ethyl cellulose, ethyl cellulose aqueous dispersion, polyethacrylate or Eudragit NE 30D, and carnauba wax. The coating was performed with a fluidized bed coater. Afterwards the coated microparticles were characterized in terms of particle size, morphology, and drug content. The drug dissolution was also investigated in pH 7.4 phosphate buffer. In our attempts for production of extended release ibuprofen microparticles coated with polymeric films, it was shown that the coating process had a significant effect on drug release. The undesired burst release of ibuprofen was observed in all film-coated microparticulate formulations, resulting from the imperfection of coating films.