Evaluation of intestinal permeation enhancement with carboxymethyl chitosan-rhein polymeric micelles for oral delivery of paclitaxel

Polymeric micelles (PMs) are currently under investigation as potential nanocarriers for oral administration of paclitaxel (PTX). Previously, we developed amphiphilic carboxymethyl chitosan-rhein (CR) conjugate for oral delivery of PTX. PTX-loaded CR PMs exhibited a homogeneous and small size (< 200 nm) with a drug loading capacity (DL) of 35.46 +/- 1.07%. However, The absorption parameters of PTX using CR PMs have not been studied before. Here, we evaluated the intestinal permeation of CR PMs by in situ intestinal absorption experiments. PTX-loaded CR PMs enhanced the absorption of PTX in the intestine without causing significant intestinal villi injury. Compared to the P-glycoprotein (P-gp) inhibition of verapamil, the transport mechanism of CR PMs across intestinal epithelial cells may bypass P-gp efflux. Caco-2 cell uptake assays also confirmed that CR PMs can be taken up into the enterocyte as whole and independent of P-gp. Local biodistribution evaluation showed that fluorescence-labeled CR PMs were absorbed into the intestinal villi. In vivo bioimaging of tumor-bearing mice verified a significant portion of CR PMs were intactly absorbed through the intestine, then distributed and accumulated at the tumor site. For their significant intestinal permeation enhancement, CR PMs might be considered as promising oral delivery carriers for PTX and other water-insoluble drugs.