ABSTRACT:
The prospects of natural polymers are brighter as synthetic polymers have certain disadvantages such as high cost, toxicity, environmental pollution during synthesis, non renewable sources, side effects and less patient compliance. The purpose of the present research was to develop a quick and slow biphasic delivery system for Carvedilol. A compressed coated tablet made of a sustained release core tablet and an immediate release coat tablet was prepared by direct compression. Both the core and the coat contained Carvedilol. The sustained release effect was achieved with a polymer HPMC K4M and PEO WSR 205 to modulate the release of the drug. The in vitro drug release profile from these tablets showed the desired biphasic release behavior. The powder blends were evaluated for angle of repose, bulk density, compressibility index and drug content. The tablets were subjected to thickness, diameter, weight variation test, drug content, hardness, friability, disintegration and in vitro drug release studies. The powder blend showed satisfactory flow properties, compressibility and drug content. All the tablet formulations showed acceptable pharmaco-technical properties and complied with in-house specifications for tested parameters. The Carvedilol contained in the fast releasing component was released within 3 minutes, whereas the drug in the core tablet was released at different times (˜16 or >24 hrs), depending on the composition of the matrix tablet. Based on the release kinetic parameters calculated, it can be concluded that the batches F6 and F7 shows best similarity with theoretical profile and were suitable for providing a constant and controlled release (zero order) for a once a day administration. The mechanism of drug release from all batches was Fickian diffusion or anomalous behavior.