RESUMO
OBJECTIVE: To develop an easy to scale-up preparation process for exenatide-loaded long-acting microspheres, and develop a method that can be used to rapidly evaluate the in vitro release properties of the microspheres. METHODS: The primary emulsion could be made by high shear emulsification process combined with high pressure homogenization method, then exenatide-loaded microspheres were prepared by a modified coacervation method. In the coacervation step, static mixer was used for mixing the primary emulsion and the coacervation reagent. RESULTS: High pressure homogenization could reduce the size of the primary emulsion to about 200 nm. The encapsulation efficiency of microspheres was greater than 96.8%, and the amount of burst release in 1 h was less than 0.5%. When the scale of microspheres preparation was magnified by five times, the characteristics of the obtained microspheres was the same as the small scale batch. The in vitro release curves showed that the continued release time lasted for nearly 4 weeks after the 17 d lag phase. The drug release rate at 45℃ was as high as 2.5 times of that at 37℃, with same release curves. CONCLUSION: The established preparation process of exenatide-loaded long-acting microspheres, which uses static mixer for mixing the primary emulsion and coacervation reagent, is easy for scaling-up and industrialization. Accelerated test at 45℃ can be used to rapidly evaluate the in vitro release profile of the microspheres.