Formulation and In vitro Evaluation of Simvastatin Microspheres Using Ethyl Cellulose as the Release Retarding Polymer

The present research involves formulation of simvastatin microspheres. The microspheres were prepared by o/w solvent evaporation technique using ethyl cellulose as the release retarding polymer and span80 as surfactant. The influence of drug to polymer ratio was examined by percentage yield, particle size distribution, drug entrapment efficiency and in vitro drug release rate. The morphology of the microspheres was characterized by scanning electron microscopy. The percentage yield of F5 was high due to increased polymer concentration. The mean particle size and the drug entrapment efficiency of all the formulation increased with increasing polymer concentration. Invitro release studies were performed in phosphate buffer pH7.4 as the dissolution medium. The percentage drug release decreased with increasing polymer concentration. The percentage drug release for F5 was 46% after 6 hours. Among all formulations F5 have a significantly slower release pattern in terms of their total drug load. It indicated that the present method was an efficient method for preparing simvastatin microspheres.