[Mucopenetrating nanoparticles: vehicles for the oral administration of paclitaxel]

Paclitaxel is an anticancer drug used as solution for perfusion for the treatment of certain types of cancers. In the last years, a number of strategies have been proposed for the development of an oral formulation of this drug. However, this task is quite complicated due to the poor aqueous solubility of paclitaxel as well as the fact that this compound is substrate of the intestinal P-glycoprotein and the cytochrome P450 enzymatic complex. In this work, we have developed pegylated nanoparticles with mucopenetrating properties in order to conduct paclitaxel onto the surface of the enterocyte. These nanoparticles displayed a size of about 180 nm and a drug loading close to 15% by weight. The pharmacokinetic study in mice has shown that these nanoparticles were capable to offer therapeutic plasma levels of paclitaxel up to 72 hours. In addition, the oral relative bioavailability of paclitaxel when loaded in nanoparticles pegylated with poly(ethylene glycol) 2000 (PEG) was found to be 85%. In a subcutaneous model of tumour in mice, these pegylated nanoparticles administered orally every 3 days have demonstrated a similar efficacy than Taxol® administered intravenously every day during 9 days. All of these results suggested that these pegylated nanoparticles were capable to cross the mucus layer of the gut and, then, reach the surface of the enterocytes. The PEG molecules would facilitate the adhesion of nanoparticles to this epithelial surface, minimise the pre-systemic metabolism of paclitaxel and, thus, promote its absorption.