Biodegradable poly(glycerin citrate) and its application to controlled release of theophylline

This study reports properties of a class of biodegradable polyesters based on citric acid and glycerin, both of which are safe ingredients in food, and their usefulness for drug control release applications. Transparent thin films of poly(glycerin citrate) (PGC) prepared by condensation polymerization were characterized by dynamic mechanical analysis, tensile testing, and FTIR spectroscopy. Depending on the acid-to-glycerin molar ratios, the crosslinked films could have glass transition temperatures varying from 30 to 81 degrees C as shown by dynamic mechanical analysis. The ductile PGC films were more prone to hydrolytic degradation than poly(lactic acid). The controlled release properties of the PGC films were evaluated by a permeation study of an exemplary drug theophylline. The diffusion of theophylline in PGC film follows a Super Case II mechanism, but in PGC film modified with PEG4000, the diffusion follows approximately a Case II mechanism (near zero-order release mechanism). (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012