Preparation and Evaluation of Microspheres of Rifabutin using Eudragit Polymers

The objective of the present study was to foster the photo-stability of rifabutin, an antitubercular drug, with a sustained drug release by preparation of microspheres using eudragit polymers. Rifabutin (log p 4.218) is spiropiridyl-rifamycin derivative with low aqueous solubility. Microspheres of rifabutin were prepared by emulsion solvent diffusion process using eudragit RL PO and RS PO polymers. Microspheres were screened for dissolution, photo-stability, SEM, XRD pattern, DSC, accelerated stability, moisture uptake and flow properties. Release of the drug from these polymeric microspheres was sustained up to 12 hrs. SEM analysis confirmed spherical shape of the microspheres, while XRD and DSC graphs confirmed amorphous nature of the untreated drug and prepared microspheres. Photo and accelerated stability of the drug entrapped in microspheres was found to be improved, whereas the flow properties of the microspheres were fair to pass the test.