Exendin-4 sustained release microsphere, its injection and preparation method

The invention relates to a sustained release microsphere containing exendin-4, prepared by using emulsion-crosslinking technology. The sustained release microsphere has a W/O/W structure, wherein, the inner water phase contains exendin-4 as the main drug, the medium oil phase contains polylactic acid-glycolic acid copolymer (PLGA), and the outer water phase contains polyvinyl alcohol (PVA). The obtained microsphere has a smooth surface, the particle size of the microsphere is between 40-100 mu m, and the drug-loading rate of the microsphere is between 0.4-0.8 %. The invention also relates to an injection prepared from the sustained release microsphere. The invention further relates to a preparation method of the sustained release microsphere. The sustained release microsphere has the advantages of high drug-loading rate, high entrapment rate, stable releasing rate, long continuous release time (more than 4 weeks), biodegradable property and the like, so that the administration frequency can be reduced obviously, and surgical implantation and removal before and after administration are avoided, thus the invention is benefit for clinic application, greatly improves patient compliance. According to the invention, the therapeutic effect of long-acting anti-diabetes is achieved.