A thin polymer coating protects individual drug crystals from adverse environments and allows for controlled drug release. Current methods of producing such coatings are very demanding batch processes. Employing hollow-fiber membranes NJIT developed two easily-scalable techniques for continuous polymer coating of drug crystals/nanoparticles using cooling crystallization or anti-solvent crystallization.
For controlled drug release processes, a facile way to continuously coat nano-sized drug crystals with a biodegradable polymer required to produce large amounts of individually coated particles. The same need exists for surface coating of nanoparticles in optical, electronic and chemical applications. Conventional polymer coating methods have many disadvantages: high energy consumption, low productivity, batch processing. A novel method for continuous polymer coating of drug crystals based on solid hollow-fiber cooling crystallization (SHFCC) has been developed. The solid hollow fiber-based device acts as a highly efficient heat exchanger. It is simple, straightforward and easily scalable as demonstrated by two scales of operation. Initial laboratory experiments were carried out for 5-10 minutes using the polymer Eugragit or poly(lactide-co-glycolide) (PLGA); we have now demonstrated uniform coating thickness of Eudragit on submicron silica particles even when the experiment was continued for 60-120 minutes. Coating of the drug Griseofulvin with Eudragit has been illustrated. Using a second method based on porous hollow fiber membrane-based anti-solvent crystallization (PHFAC), continuous production of polymer-coated nanoparticles and submicron particles/drug crystals has also been demonstrated. In addition we have continuously synthesized polymer-coated drug crystals from a solution of the polymer Eudragit and the drug Griseofulvin by PHFAC.
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