Air Suspension Coating for Multiparticulates

Fluidized bed systems are widely used in the pharmaceutical industry for production of core material and for film coating. Top spray coaters, evolving from the fluid bed dryers of nearly 40 years ago, produce batches of fine, coated particles in excess of 500 kg. Wurster bottom spray equipment is used to manufacture pellets as well as to coat products ranging from powders to tablets. Rotary tangential spray systems generate micro pellets (approximately 100-600 microns) from powders, macro pellets (about 700-2000 microns) by layering, and apply coatings for all types of release. For all processes, films may be applied using water, organic solvents, or via hot melt to provide sustained or controlled release, taste masking, enteric release, improved stability, or aesthetics. However, depending on the type of substrate and coating material, the air suspension method selected may be a significant process variable. In addition to formulation considerations in product development, an understanding of these types of processing techniques is essential.