[Development of Solventless Pharmaceutical Technique for Manufacture of Pharmaceuticals]

The aim of our study was to develop a solventless drug pelletization and polymer coating technique for pharmaceutical manufacturing. This review describes a dry coating technique using a mechanical powder processor and a V-shaped blender to produce coated pellets or tablets by mechanically mixing polymer particles and core materials (such as drug pellets and uncoated tablets) without the need for a solvent. First, aqueous latexes comprising colloidal polymethacrylates and ethylcellulose were solidified by freeze drying to produce polymer particles for the dry coating process. These particles and the cores were then subjected to mechanical powder processing or V-shaped blending to provide coated formulations with controlled-release characteristics. Polymer coating was achieved by using agglomerates comprising assembled colloidal polymer. The agglomerated polymer was easily pulverized during the mixing treatments due to its loose structure (the lack of close contacts between the colloidal particles), and the resulting fine polymer with high adhesiveness was deposited on the cores. Colloidal polymer dispersed in aqueous latex tends to coagulate in the freeze-drying process due to condensation of the dispersion, yielding dense agglomerates with poor coating characteristics. The presence of surfactants (such as sodium lauryl sulfate) in the latex can prevent adhesion between colloidal particles in the freeze-drying process, providing loosely structured agglomerates suitable for dry coating. Dry coating with a V-shaped blender could thus be achieved with these polymer particles instead of having to use a mechanical powder processor.