Preparation and Characterization of Nitrendipineloaded Eudragit RL 100 Microspheres Prepared by an Emulsion-Solvent Evaporation Method

Purpose: The aim of the work was to prepare nitrendipne-loaded Eudragit RL 100 microspheres to achieve sustained release nitrendipine.
Method: Nitrendipne-loaded Eudragit RL 100 microspheres were prepared by an emulsion-solvent evaporation method using ethanol/liquid paraffin system. The resultant microspheres were evaluated for average particle size, drug loading, in vitro drug release and release kinetics. FTIR spectrometry, scanning electron microscopy, differential scanning calorimetry and x-ray powder diffractometry were used to investigate the physical state of the drug in the microspheres.
Result: The mean particle size of the microspheres was influenced by varying drug:polymer ratio and emulsifier concentration while drug loading was dependent on drug:polymer ratio. The results of FTIR spectrometry, differential scanning calorimetry and x-ray diffractometry indicated the stable character of nitrendipne in drug-loaded microspheres and also revealed absence of drug-polymer interaction. The drug release profiles of the microspheres at pH 1.2 showed poor drug release characteristics while at pH 6.8, drug release was extended over a period of 8 h; release was influenced by polymer concentration and particle size. Drug release followed the Higuchi model.
Conclusion: The nitrendipine-loaded Eudragit RL 100 microspheres prepared under optimized conditions showed a good sustained release characteristics and were stable under the conditions studied.

Keywords
Nitrendipine, Eudragit RL 100, Microspheres, Physicochemical characterization, Sustained release.