Solventless-mixing particle coating using a high shear mixer for preparing coated pellets using dry methyl methacrylate and diethylaminoethyl methacrylate copolymer latex

• Solventless coating could be achieved by high shear mixing of drug pellets and polymer particles. • Polymer particles with fragile characteristics exhibited high coating performance. • Promoting the pulverization of polymer particles enhanced their coating efficiency. • Coated pellets obtained were annealed at 80 °C for 6 h and suppressed initial drug release. • Dissolution characteristics were controllable due to the thickness of coated layers. The aim of this study was to investigate the feasibility of coated pellet formulation by high shear mixing of drug pellets and polymer particles without solvent or heat. First, drug-layered pellets were prepared by high shear mixing of drug crystals and sugar-cellulose pellets. Second, aqueous methyl methacrylate and diethylaminoethyl methacrylate copolymer latex was solidified by freeze drying to produce dry latex comprising colloidal polymer. Finally, the resulting pellets and latex were exposed to high shear mixing, and the obtained coated pellets were characterized. The freeze-dried latex exhibited high coating performance due to its fragile characteristics, which were due to the lack of close contacts between the colloids. This latex was easily pulverized by high shear mixing with the pellets, and the resulting fragments were then deposited on the surface of the pellets. We examined additional coatings: after high shear mixing of the drug-layered pellets and latex particles, fresh latex was added and mixed with the coated pellets. This process provided coated pellets with thick and dense polymer layers, which could suppress initial drug release after annealed at 80 °C for 6 h. The dissolution was dependent on the coating thickness, which was determined by controlling the amount of coated polymer.