Preparation and in vitro release of rifampin microspheres encapsulated in biodegradable polyesters

Microspheres containing antiphthisic drug Rifampin were prepared from poly (lactide-co-glycolide) (PLGA) as carrier by emulsion and solvent evaporation method. The conditions of the microsphere preparation such as the drug/carrier molar ratio, the volume ratio of organic solvent to water, PLGA concentration in organic solvent, speed of emulsification, kind of stabilizer, relative molecular weight of PLGA, LLA/GA mass ratio were discussed. The surface morphology of the microspheres in original and degraded states was observed by SEM. The mean diameter and drug content of microspheres were examined, and the drug release in vitro was evaluated. The morphology of the microspheres prepared from PLGA and by 1% gelatin as the stabilizer was integral with 10-30 mum diameter range, 24.3% average drug content, 42-84 d drug-release time. The drug-release kinetics with zero order satisfies the requirements of controlled drug-release.