摘要Monomethoxy poly(ethylene glycol)-block-poly(D,L-lactic acid)(PEG-PLA)is a typical amphiphilic di-block copolymer widely used as a nanoparticle carrier(nanocarrier)in drug delivery.Un-derstanding the in vivo fate of PEG-PLA is required to evaluate its overall safety and promote the devel-opment of PEG-PLA-based nanocarrier drug delivery systems.However,acquiring such understanding is limited by the lack of a suitable analytical method for the bioassay of PEG-PLA.In this study,the phar-macokinetics,biodistribution,metabolism and excretion of PEG-PLA were investigated in rat after intra-venous administration.The results show that unchanged PEG-PLA is mainly distributed to spleen,liver,and kidney before being eliminated in urine over 48 h mainly(＞80％)in the form of its PEG metabolite.Our study provides a clear and comprehensive picture of the in vivo fate of PEG-PLA which we anticipate will facilitate the scientific design and safety evaluation of PEG-PLA-based nanocarrier drug delivery systems and thereby enhance their clinical development.