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Development and application of a process window for achieving high-quality coating in a fluidized bed coating process
F L Laksmana1, P J A Hartman Kok, H Vromans
1Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands. F.L.Laksmana@gmail.com
AAPS Pharmscitech
|June 5, 2009
Summary
Optimizing fluidized bed coating requires controlling process conditions. This study defines an operational window using bed relative humidity and droplet size to achieve optimal coating quality by managing particle layering and agglomeration.
Area of Science:
- Pharmaceutical Sciences
- Chemical Engineering
- Materials Science
Background:
- Coating quality in fluidized bed coaters is influenced by both formulation and process conditions.
- Understanding the interplay between process parameters is crucial for reproducible coating outcomes.
Purpose of the Study:
- To establish an operational window for fluidized bed coating, differentiating between layering and agglomeration regimes.
- To identify conditions yielding the highest coating quality, characterized by thickness distribution, porosity, and pore size.
Main Methods:
- Utilized engineering models to predict bed relative humidity and coating aerosol droplet size.
- Employed quantitative image analysis to assess coating quality metrics.
- Investigated the role of the viscous Stokes number (DeltaSt(v)) in achieving the layering regime.
Main Results:
- The layering regime is attainable at a specific excess of viscous Stokes number (DeltaSt(v)), which is dependent on bed relative humidity and droplet size.
- Higher bed relative humidity necessitates a greater DeltaSt(v) to maintain the layering regime.
- Bed relative humidity and droplet size alone are insufficient for consistent coating quality; fractional area of particles sprayed per unit time is a key additional parameter.
Conclusions:
- An operational window for fluidized bed coating can be defined using bed relative humidity, droplet size, and fractional spray rate.
- Optimal coating quality is achieved near saturation with fine droplets for high spray rates, ensuring complete particle coverage without agglomeration.
