Impact of surfactant treatment of paclitaxel nanocrystals on biodistribution and tumor accumulation in tumor-bearing mice

We have previously tested paclitaxel nanocrystals (PTX-NCs) in tumor murine models and learned that the nano-crystal formulation could achieve similar and superior anticancer efficacy to the conventional Taxol (R) formulation, but with significantly reduced side-effects. The nanocrystals were not coated with any surfactants and a majority of the injected dose was taken up by the liver (>40%), while a minimal amount was present in the blood circulation and quickly eliminated. The aim of this work was to treat the surface of PTX-NCs with PEG-based polymers and examine the impact by surface coating on biodistribution, pharmacokinetics, and tumor retention. Testing in tumor-bearing mice showed that PTX-NCs treated with Pluronic (R) F68 (PEG-PPG-PEG block polymer) significantly enhanced blood circulation of the drug and accumulation in tumor tissue. The absolute amount reaching the tumor, however, was still minimal relative to the dose. (C) 2016 Elsevier B.V. All rights reserved.