Abstract

Levonorgestrel (LNG) loaded biodegradable microspheres, with different drug loading and polymer composition, were prepared by emulsion solvent evaporation technique. In vitro release profiles of these microspheres were studied in ethanolic phosphate buffered saline pH 7.4 (EPBS). The effect of different percentages of ethanol in the dissolution media on the release profiles of LNG from the micropheres, with varying drug load and polymer composition, was determined. The release kinetics of LNG from the microspheres was evaluated by fitting the release data to the zero order, first order, Higuchi, Korsmeyer-Peppas and Baker-Lonsdale equations. Initial examinations revealed that the release data followed more than one kinetic model. Diffusional rate treatment was used to distinguish between different kinetic models. The release kinetics of LNG from the microspheres was observed to be dependant on the ethanol content of the dissolution media.