(517b) A Novel Technique for Continuous Production of Polymer-Coated Drug Crystals
To develop controlled release of a drug as well as to protect the drug from demanding environments, appropriate polymeric coatings are often employed on the drug crystals. Conventional methods for coating or encapsulating micron–sized crystals and nanoparticles utilize dry or wet approaches. Dry methods include physical vapor deposition, plasma treatment, chemical vapor deposition and pyrolysis of polymeric organic materials. Wet methods cover sol-gel processes, emulsification and solvent evaporation techniques. Supercritical fluid (SCF) processes such as Rapid Expansion of Supercritical Solutions (RESS), Supercritical Anti-Solvent (SAS), and Gas Anti-Solvent (GAS) processes employing supercritical CO2 are alternative methods for nanoparticle coating or encapsulation of ultrafine particles/crystals. These SCF-based processes have many shortcomings. Some processes require demanding operating conditions, suffer from low polymer solubility etc. Most of these techniques are also batch processes. Fluidized bed-based processes, which can be continuous, face difficulties with nanoparticles caused by van der Waals and other interparticle forces. In all such processes, scale-up is also quite demanding.
We will illustrate a novel technique allowing a continuous process of producing polymer-coated drug crystals. This process is also easily scalable. It is different from the solid hollow fiber cooling crystallization-based technique we have also recently developed . Polymers used for coating were Eudragit and PLGA.
 Chen et al., Ind. Eng. Chem. Res. 2014, 53, 6388−6400.