Novel Method for Introducing Dry Powder Directly into the Spray Zone of a Bottom Spray Wurster Coating Process

Wurster coating of multi-particulates with polymer suspensions and solutions is widespread in the pharmaceutical industry. Several formulations for polymer coatings of aqueous dispersions and organic solvent based polymer systems require glidants such as talc to be suspended into the polymer solutions to cut down on polymer tackiness and reduce agglomeration. These glidants can fall out of solution during the process, causing gun plugging, line plugging, extended processing times and inefficient coating. This study focuses on a modification to an existing Wurster spray system to add solid glidants via a powder feeder in dry form during the Wurster coating process.

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