Drug-loaded microspheres are significant for the development of modern pharmaceutical products. It is well known that the taken of aspirin for long-term increases the risk of serious gastrointestinal complications

therefore a controllable delivery of aspirin is of importance to lighten those side effects. In this work

poly(lactic acid) (PLA) was chosen as the carrier to prepare PLA-aspirin microspheres by using the traditional and the improved solvent evaporation methods. It was found that no matter which experimental condition was

the encapsulation efficiency of aspirin was higher by using the improved method than that of the traditional method. Specifically

when the concentration of polyvinyl alcohol = 1% (mass)

the polymer concentration = 1:20

the oil/water rate = 1:2.5

PLA-aspirin microspheres were obtained

via

the improved method with a high yield of 82.83% (mass) and an encapsulation efficiency of 44.09%. PLA-aspirin microspheres were then prepared continuously using the improved method

which further enhanced the encapsulation efficiency to 54.56%. Approximate 85% aspirin released from microspheres within 7 days. Obvious degradation which was represe

nted by reduction on hardness was observed by soaking microspheres in PBS for 60 days. This work is of interest because it provides a continuous route to prepare PLA-aspirin microspheres continuously with a high drug encapsulation efficiency.