Stable phosphatidylcholine-bile salt mixed micelles enhance oral absorption of paclitaxel: preparation and mechanism in rats.

The aim of this study is to prepare a stable phosphatidylcholine/bile salt micelles with Pluronic F127-polyethylenimine conjugates (F127-PEI), d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), soybean phosphatidylcholine (SPC) and sodium cholate (NaC) and to elucidate the effects and possible mechanism of micelle components on the intestinal absorption of paclitaxel (PTX) in rats. The results of intestinal absorption revealed that the PTX in SPC/NaC micelles displayed superior permeability across intestinal barrier than free drug and PTX in TPGS/SPC/NaC and F127-PEI/TPGS/SPC/NaC mixed micelles exhibited the strongest permeability across intestinal barrier. These results were also proved by the studies on cell uptake tests. The mechanism was demonstrated in connection with inhibition of the efflux mediated by intestinal P-gp and enhancement of the drug transportation across the unstirred water layer to the endothelial lining, thereby promoting the permeation across the intestinal wall. Pharmacokinetic study demonstrated that the area under the plasma concentration-time curve (AUC0→∞) of paclitaxel in F127-PEI/TPGS/SPC/NaC micelles was much greater than that in TPGS/SPC/NaC micelles. This phenomenon deviated from the results of uptake studies by cells and permeability experiments through rat intestine and revealed that the micelle stability had a great effect on intestinal absorption of paclitaxel.