Microencapsulation of Solid Dispersions of Felodipine and Characterization of Release Mechanism

Abstract

The study was aimed at increase the solubility of poorly soluble drug Felodipine and formulating it in sustained release dosage form. Solid dispersion of drug was prepared using Poly vinyl pyrollidone (PVP) and hydroxyl propyl methyl cellulose (HPMC) as inert hydrophilic carriers by kneading method. A 17-fold increase in dissolution rate of Felodipine was observed with solid dispersion prepared with HPMC. Optimized solid dispersion was further characterized by Powder X-ray diffraction (PXRD) which suggest transformation of crystalline Felodipine in amorphous form and Fourier transform infrared spectroscopy (FTIR) suggesting no possible interaction. Sustained release microcapsules of Felodipine were formulated using ethyl cellulose (EC) and Eudragit® RL 100 (EDRL) as coating material with solid dispersion of Felodipine as core by emulsion solvent evaporation method. Gelatin was used as microencapsulating agent employing coacervation-phase separation technique. Microcapsules from all the batches were found to discrete, spherical and free flowing and % entrapment efficiency was found to be in range of 88% to 96%. All the batches of microcapsules showed sustained release curve in pH 7.4 phosphate buffer up to eight hours with microcapsules prepared with gelatin giving Felodipine release up to 86% after 8 hrs. XRD pattern studies of the microcapsules made of gelatin showed drug still present in the amorphous form and thus maintaining its solubility in the microcapsule system.