国生 Coating Method 国生 Coating methods 国生一 Film defects ®Compression coating 象tin 多Roll coating Can be usedfor combinat 多日 which can buarst to foem wrinkdes ·Disadvanages exacerbated by pooc adhesioe ffi to tabletce Significant increse in tblet weight. Reduce drying air temperture. .Possible to produce tablets with no inner core 国生 Film defects 国2线Film defects 国生一 Film defects Picking桔连 象Blooming起霜 需Moutling色斑 .Areas of tablet suface are not eowered byfilm co Uneven color distribution in fi .Overwet tablets stick together and pflm off surface as they move apurt film to tablet surface. Decrease spaying rae Increasedrying temperare .Decrease temperued lngth of drying process Alter suspesio prepapigmen weight of pl 图t生Film defects 国生 Film defects 国Film defects Orange Peelh橘皮状 ●Bridging桥接 需Cracking,.splitin吗peeling开裂和脱落 .Fm ufe has arough finish resembling orange Fam forms abridge over igationsng them The film cracks on the crown of the surface or splits peel. High inema streses infi pulling the by presencefloos and the flae. on tablet surface. film off the surface of theion. High stresses in the fim tat cannot be relieved due Reduce solids coeent of coating suspension.Reduce Increase adhesion ofcoo tblet by changing core dryin temper visity of polyer muioAdd plsnplsic Increase plasticcooUse 1919 Shanghai Jiao Tong University Coating Method Compression coating • Advantages • It is a dry process, so suitable for moisture-sensitive compounds. • Can be used for combination products where the active substances are incompatible. • Disadvantages • Significant increase in tablet weight. • Possible to produce tablets with no inner core. Shanghai Jiao Tong University Coating methods Pan coating Roll coating Fluidized bed coating Shanghai Jiao Tong University Film defects Wrinkling皱纹 or blistering起泡 • Film detaches from tablet surface causing blister which can burst to form wrinkles • Gases forming on tablet surface during coating; exacerbated by poor adhesion of film to tablet surface. • Reduce drying air temperature. Shanghai Jiao Tong University Film defects Picking粘连 • Areas of tablet surface are not covered by film coat. • Overwet tablets stick together and pull film off surface as they move apart. • Decrease spraying rate. Increase drying temperature Shanghai Jiao Tong University Film defects Blooming起霜 • Dulling of surface, normally after prolonged storage. • Migration of low molecular weight components of film to tablet surface. • Decrease temperature and length of drying process. Increase molecular weight of plasticizer. Shanghai Jiao Tong University Film defects Mottling色斑 • Uneven color distribution in film. • Inadequate pigment dispersion. Color migration, a problem with dyes and lakes rather than pigments. • Alter suspension preparation to ensure pigment aggregates are dispersed. Replace dyes with pigments. Shanghai Jiao Tong University Film defects Orange Peel橘皮状 • Film surface has a rough finish resembling orange peel. • Film coat droplets are too dry or too viscous to spread on tablet surface. • Reduce solids content of coating suspension. Reduce drying temperature. Reduce viscosity of polymer. Shanghai Jiao Tong University Film defects Bridging桥接 • Film forms a bridge over intagliations, leaving them indistinct. • High internal stresses in film relieved by pulling the film off the surface of the intagliation. • Increase adhesion of coat to tablet by changing core formulation. Add plasticizer or increase plasticiser concentration. Alter geometry of intagliations. Shanghai Jiao Tong University Film defects Cracking, splitting, peeling开裂和脱落 • The film cracks on the crown of the surface or splits on the tablet edge. Can be differentiated from picking by presence of loose film around the flaw. • High stresses in the film that cannot be relieved due to the strong adhesion of the film to the tablet surface. • Increase plasticizer concentration. Use stronger polymer