摘要：In treatment of diabetes, it is much desired in clinics and challenging in pharmaceutics and material science to set up a long-acting drug delivery system. This study was aimed at constructing a new delivery system using thermogelling PEG/polyester copolymers. Liraglutide, a fatty acid-modified antidiabetic polypeptide, was selected as the model drug. The thermogelling polymers were presented by poly(ε-caprolactone-co-glycolic acid)-poly(ethylene glycol)-poly(ε-caprolactone-co-glycolic acid) (PCGA-PEG-PCGA) and poly(lactic acid-co-glycolic acid)-poly(ethylene glycol)-poly(lactic acid-co-glycolic acid) (PLGA-PEG-PLGA). Both the copolymers were soluble in water, and their concentrated solutions underwent temperature-induced sol-gel transitions. The drug-loaded polymer solutions were injectable at room temperature and gelled in situ at body temperature. Particularly, the liraglutide-loaded PCGA-PEG-PCGA thermogel formulation exhibited a sustained drug release manner over one week in both in vitro and in vivo tests. This feature was attributed to the combined effects of an appropriate drug/polymer interaction and a high chain mobility of the carrier polymer, which facilitated the sustained diffusion of drug out of the thermogel. Finally, a single subcutaneous injection of this formulation showed a remarkably improved glucose tolerance of mice for one week. Hence, the present study not only developed a promising long-acting antidiabetic formulation, but also put forward a combined strategy for controlled delivery of polypeptide.
