Comparison of solvent evaporation and ultrasonic-assisted production methods in the development of nimesulide nanosponges and their characterization

Purpose: To compare solvent evaporation and ultrasonic assisted synthesis in preparation of nimesulide nanosponges using polyvinyl-alcohol and Eudragit L100 as a polymer/copolymer and dichloromethane as a cross linker. Methods: Twelve formulations of nimesulide were prepared, six with each method by varying the ratios of both polymer and co-polymer. The resulting nanosponges were evaluated characterized by preformulation studies, production yield (%), differential scanning calorimeter, x-ray diffraction, Fourier transformation infrared spectroscopy, scanning electron microscopy, entrapment efficiency (%), actual drug content (%) and in-vitro dissolution studies. Results: The results revealed that the formulation with high amounts of co-polymer in both methods showed crystalline structures with enhanced dissolution rates in basic media. Drug entrapment was higher for products prepared by solvent evaporation method (74 %) than that prepared by ultrasonic assisted method (61 %). This correlates with the enhanced dissolution rates for products by solvent evaporation method and increased solubility due to drug-polymer complex formation. Conclusion: Formulations made by solvent evaporation method demonstrate higher production yield and drug entrapment. However, both methods exhibit enhanced dissolution rates in basic medium generally as well as other characteristics that are comparable to nanosponges reported in the literature with regard to their comb like structure.