Abstract: To study the tissue distribution and antitumor effect of a new preparation paclitaxelloaded nanoparticles (PCTN) injection in tumorbearing mice. Methods: Kunming breed mice were subcutaneously inoculated hepatoma H22 cell to the armpit of forelimb, and then injected PCTN and Toxal injection (PCT) into tail vein. The concentration of paclitaxel in tissue was determined by liquid chromatographytandem mass spectrometry. Results: Paclitaxel was mainly found in pancreas, ovary and spleen and it was higher in PCTN than in PCT (P<0.05), and PCTN on the concentration of 2.5?mg/kg had the most efficacious inhibiting effect on tumor, whereas there was no obvious difference between PCTN and PCT in other tissues of tumorbearing mice (P>0.05). Conclusions: Both PCTN and PCT have obvious inhibiting effect on tumor, and the targeting efficiency of PCTN in

Key words: Paclitaxel, Nanoparticles, Liquid chromatographytandem mass spectrometry, Tissue distribution