Abstract
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. Tropical Journal of Pharmaceutical Research Vol. 7 (3) 2008: pp. 1033-1041
Highlights
Microspheres are one of the particulate delivery systems used to achieve sustained or controlled drug delivery, improve bioavailability and stability and target drug to specific sites
The particle size of the microspheres increased from 14.25 ± 6.85 to 42.15 ± 12.34 μm with increasing polymer concentration (Table 1)
It was observed that increasing the emulsifier concentration decreased the microsphere size
Summary
Microspheres are one of the particulate delivery systems used to achieve sustained or controlled drug delivery, improve bioavailability and stability and target drug to specific sites. The Eudragits are biocompatible copolymers synthesized from acrylic and methacrylic acid esters These polymers are well tolerated by the skin and have been used in the formulation of dosage forms especially matrix tablets for oral sustained release[3, 4, 5] and in tablet coating[6]. They have been used in the microencapsulation of drugs[7, 8, 9]. The present study was undertaken to prepare sustained release microspheres of nitrendipne using Eudragit RL 100 by the emulsion solvent evaporation method. The physical state of the nitrendipne was studied using FTIR, DSC, and X-ray diffractrometry
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