title: Fluid-bed coater modifications and study of their influence on the coating process of pellets.
abstract: OBJECTIVE
  In this study, different modifications of bottom spray fluid-bed coater with draft tube inserted were characterized and evaluated.
  
  
  METHODS
  After coating the neutral pellets with polymeric solution comprising coloring agent pellet batches were characterized for coating variation, yield and degree of agglomeration.
  
  
  RESULTS
  Funnel-shaped distribution plate was found to improve process yield and decrease the degree of agglomeration at selected values of process parameters, whereas coating uniformity was worse in all cases when compared to conventional Wurster chamber. Results of the coating chamber with the swirl airflow generator indicate more uniform deposition of the coating material and in some cases an improved process yield and decreased formation of agglomerates when compared to conventional Wurster chamber. In series of experiments using Wurster chamber, having tangentially oriented air intake slots, which enabled introduction of air above the distribution plate, coating layer was more uniformly deposited on the pellet cores and formation of agglomerates was lower compared to the results obtained in a conventional Wurster coating chamber.
  
  
  CONCLUSIONS
  Modifications of Wurster coating process by introducing swirling air motion within the draft tube or by introduction of air above the distribution plate have at selected values of process parameters resulted in reduced per-particle coating variation, degree of agglomeration and improved process yield.
authors.affiliation: Faculty of Pharmacy, University of Ljubljana, Aškercˇeva, Ljubljana, Slovenia. rok.dreu@ffa.uni-lj.si
authors.forename: Rok
authors.initials: R
authors.lastname: Dreu
authors.forename: Matevž
authors.initials: M
authors.lastname: Luštrik
authors.forename: Matjaž
authors.initials: M
authors.lastname: Perpar
authors.forename: Iztok
authors.initials: I
authors.lastname: Zun
authors.forename: Stanko
authors.initials: S
authors.lastname: Srčič
mesh_terms: D004867:Equipment Design; D010316:Particle Size; D015203:Reproducibility of Results; D013499:Surface Properties; D013678:Technology, Pharmaceutical / Q000379:methods*