Continuous wet granulation using fluidized-bed techniques I. Examination of powder mixing kinetics and preliminary granulation experiments

• Published in: European journal of pharmaceutics and biopharmaceutics 1999-11, Vol.48 (3), p.189-197
• Main Authors: Gotthardt, Silke, Knoch, Axel, Lee, Geoffrey
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Chemistry, Pharmaceutical; Continuous granulation; Drug Compounding - instrumentation; Drug Compounding - methods; Drug Industry - instrumentation; Drug Industry - methods; General pharmacology; Kinetics; Mathematical Computing; Medical sciences; Particle Size; Pharmaceutical technology. Pharmaceutical industry; Pharmacology. Drug treatments; Powders; Tablets; Wettability
• ISSN: 0939-6411; 1873-3441
• DOI: 10.1016/S0939-6411(99)00050-8

The movement of powder/granules within the reaction chambers of two continuously-operating granulators (Niro/Aeromatic-Fielder Contipharm and the Glatt Continuous Fluidized-Bed Granulator) was examined by adding dyestuffs to the powder-inlet. Comparison of the dye mass-fraction in the product with the appropriate transport equation indicated random mixing and transport within the product-chamber. Photographs of powder movement on the gill-plate of the Contipharm showed, however, air-driven transport of powder from inlet to outlet, which evidently does not prevent overall random mixing. The output half-life is >20 min, showing substantial residence time within each machine. A simplex granule was also prepared using the two machines. With the Niro it was shown that an increase in binder solution spraying rate during the continuous process produced an increase in particle size distribution and moisture content. Reduction of air volumetric flow rate on the Glatt machine during continuous operation produced higher moisture content of the product. It was thus demonstrated that changes in process conditions during continuous operation produce predictable alterations in product properties.