Effect of Preparation Temperature on Ethylcellulose Microsphere Properties Prepared by Oil-in-Oil Emulsion Solvent Evaporation Process

Abstract

The present study aims to formulate ethylcellulose microspheres using the oil-in-oil emulsion solvent evaporation method and judge the outcome of processing temperature on their features. The effects of the evaporation rate of the solvent on the particle properties and drug release characteristics of the microspheres were studied. Here, microspheres were prepared at different processing temperatues, viz., 10 0 C, 25 0 C, and 40 0 C, and their impact on the various characteristics of microspheres like surface topography, micrometrics, yield percent, encapsulation efficiency, in vitro dissolution, Fourier-transform infrared spectroscopy (FTIR) and release kinetics were elaborately studied. The FTIR study revealed that processing temperature did not affect drug-polymer compatibility. The study observed that the processing temperature had a great influence on the various characteristics of the prepared microsphere. It was observed from sieve analysis that the mean particle size of the microsphere increased with an increase in processing temperature, and the SEM study also corroborated the same result. SEM photographs showed processing at a higher temperature resulted in particles with a smooth surface, in contrast to a lower processing temperature that forms a bumpy surface. Furthermore, a higher temperature favoured formulation with a higher entrapment efficiency (94.42 ± 0.9 %) as compared to a lower temperature (85.2 ± 0.72 %). For a noteworthy timeframe, indinavir sulfate frames a solid solution in the ethylcellulose matrix and proceeds with the amorphous state. The results of an in vitro drug dissolution study showed that microspheres formulated at a higher temperature had a more sustaining effect as compared to those formulated at a lower temperature, which may have resulted due to their higher mean particle size. Using the Korsemeyer Peppas power law, it was found that the way drugs are released is controlled by diffusion.