Optimization of Pellet Coating Techniques

In the present study, pellets were prepared and optimization of pellets coating technique was done. Extrusion-spheronization technique was employed to prepare pellets by optimizing operational variables like spheronization time, spheronization speed and percent of granulating fluid to obtain smooth and spherical pellets. Pellets were coated employing spray coating and powder layered coating techniques in order to obtain sustained release. Hydroxy Propyl Methyl Cellulose (HPMC) K-15M was used as a coating polymer. Diclofenac sodium loaded pellets (20%) were prepared with 76% MCC and PVP K-30 at spheronization speed of 120 RPM for 20 min using 76% granulating fluid. Spray coating was done employing HPMC K-15M solution (1%) in (70: 30) water: ethanol mixture. Powder layering was done using 5% PVP K-30 in (50: 50) ethanol: water mixture as binder solution and powdered HPMC K-15M. Both the processes were continued till 5% coating level was achieved. Powder layered and spray coated pellets were evaluated for physical characteristics like drug content and in-vitro drug release. Physical characteristics like angle of repose, bulk density, tapped density, friability, moisture content and percentage drug content were found to be within standard limits. In-vitro drug release was found to be 0.5 to 1% in pH 1.2 buffer from both the pellets. In pH 6.8 buffer powder layered pellets showed 25% drug release, while spray coated pellets showed 45% drug release after 7 h. From the above study, it was concluded that powder layered pellets sustain drug release more than spray coated pellets.