Exenatide-loaded PLGA microspheres with improved glycemic control: in vitro bioactivity and in vivo pharmacokinetic profiles after subcutaneous administration to SD rats.

A subcutaneous exenatide delivery system was developed and characterized in vitro and in vivo. The results clearly showed that the exenatide loaded PLGA microspheres prepared by using a non-aqueous processing medium had low burst release and high drug encapsulation efficiency. Exenatide loaded in the microspheres preserved its bioactivity. The pharmacokinetics parameters were determined after subcutaneous administration of microspheres to SD rats. The plasma concentration of the single dose of the sustained-release microspheres attained C(max) of 108.19±14.92 ng/ml at t(max) of 1.33±0.58 h and the t(½) was 120.65±44.18 h. There was a linear correlation between the in vitro and in vivo release behavior (R²=0.888). Exenatide loaded microspheres may prove to have great potential for clinical use.