Study on rifampicin polylactic acid microspheres:Effect of molecular weight of polylactic acid (PLA) on the properties of microspheres

Key words: 
• polylactic acid /
• microspheres /
• molecular weight /
• rifampicin

Abstract: OBJECTIVE To discover the effect of molecular weight of PLA on the properties of rifampicin polylactic acid microspheres.METHODS Rifampicin polylactic acid microspheres were prepared by dispersion-solvent diffusion method.The microsphere size distribution and drug encapsulation efficiency were determined.The experiments on in vitro releasing property and stability of the microspheres were also carried out.RESULTS The relationship between molecular weight of PLA and the particle size distribution had not been seen. PLA of low molecular weight could decrease the drug encapsulation efficiency and accelerate the drug releasing rate.The experiments on stability showed that the microspheres were stable under 4℃or room temperature.Fusion and aggregation of the microspheres happened under 37℃ due to low glasstransition temperature of PLA polymer.CONCLUSION PLA microspheres of proper characteristics should be prepared from polylactic acid of certain molecular weight.