Abstract
A new practical method of controlling the moisture content of particles in an aqueous polymeric coating by a tumbling fluidized bed is described. The method was based on the on-line measurement and feedback control of moisture content by use of an IR (infrared) moisture sensor. Spherical core particles made of crystalline cellulose were coated in the tumbling fluidized bed by atomizing the suspension of enteric acrylic copolymer (Eudragit L30D-55). The influence of moisture control, conducted with different methods (PID (proportional-integral-derivative) control and on-off control), on the drug release rate and on the agglomeration tendency of coated particles was investigated. It was found that moisture control by the PID control method was useful for producing the desired coated particles which exhibited excellent properties in delayed release with a low agglomeration tendency.
