Development of Sustained-Release Microbeads of Nifedipine and In vitro Characterization

Purpose: To formulate and evaluate sustained-release microbeads of nifedipine for prolonged delivery. Methods: Nifedipine microbeads were prepared using sodium alginate and pectin in different ratios by ionic-gelation method. The microbeads were evaluated for surface morphology and shape by scanning electron microscopy (SEM), micromeritic properties, microencapsulation efficiency and in vitro drug release. The microbeads were also assessed by Fourier Transform Infra-red Spectroscopy (FTIR) and differential scanning calorimetry (DSC) to determine drug-polymer interaction, if any. Results: FTIR and DSC results indicate absence of interaction between the drug and polymers used. Good rheological behavior was demonstrated with an angle of repose < 30º, and Carr's index and Hausner's ratio of < 10% and < 1.12, respectively Microbead size, yield and entrapment efficiency were in the range of 695 to 733 um, 69 to 75% and 54 to 63%, respectively. SEM revealed that the microbeads were discrete, largely spherical and free-flowing. Higuchi model was the best fit for the dissolution data and followed non-Fickian diffusion mechanism. Conclusion: The microbead formulation would be suitable for sustained release of nifedipine.