Electronic Thesis and Dissertation Repository


Master of Science


Chemical and Biochemical Engineering


Dr. Jesse Zhu


The conventional coating of pharmaceutical pellets is achieved by liquid-based coating techniques using a fluidized bed or a pan coater. However, many restrictions and drawbacks such as long processing time and large energy consumption exist in the above method. Dry powder coating technique is a novel solventless coating technique that is able to mitigate the problems of liquid-based coating. In this study, a newly invented coating apparatus called rotary fluidized bed (RFB), was applied for the coating of pharmaceutical pellets by a dry powder coating process. The RFB has a unique structure where the hot fluidizing air is further aided by the rotation to ensure a uniform coating. Results of SEM micrographs indicated the piroxicam pellets formed continuous and dense coating film in the RFB. In-vitro drug release tests confirmed that the dry powder coated pellets successfully achieved immediate release, sustained release and delayed release with Eudragit® EPO, Eudragit® RS/RL and Acryl-EZE, respectively. The optimal operation conditions were as follows: curing temperature 2 h, curing temperature 50 oC, RFB rotating speed ~20 rpm, liquid plasticizer spraying rate ~0.25 g/min and fluidizing air flowrate ~35 L/min. The RFB demonstrated a comparable film formation quality and coating efficiency with the pan coater, while superior to the fluidized bed. For the more difficult-to-coat micronized pellets (0.1-0.3mm), the RFB presented better applicable potential than the other two apparatus. In conclusion, the RFB is a promising dry powder coating apparatus for pharmaceutical pellets coating.