Preparation and evaluation in vitro and in vivo of docetaxel loaded mixed micelles for oral administration

A mixed micelle that comprised of monomethylol poly(ethylene glycol)-poly(D,L-lactic acid) (MPP), D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) and stearic acid grafted chitosan oligosaccharide(CSO-SA) copolymers was developed to enhance the oral absorption of docetaxel (DTX). DTX-loaded MPP/TPGS/CSO-SA mixed polymeric micelles (MPMs) were prepared with thin film hydration method and characterized in terms of morphology, size, zeta potential, encapsulation efficiency, critical micellization concentration, and in vitro stability in media modeling physiological conditions. The in vitro release of docetaxel from the mixed micelles was studied with dialysis method. The oral bioavailability studies were conducted in rats and the pharmacokinetic parameters were evaluated. The results showed that DTX-loaded MPP/TPGS/CSO-SA MPMs had a mean diameter of 34.96 nm and exhibited spherical shape under transmission electron microscopy. The drug loading of DTX in the mixed micelles was 19.15%. The critical micellization concentration of MPP/TPGS/CSO-SA copolymer was 2.11 x 10(-5) M, and the size of mixed micelles in gastric fluid (pH 1.6) for 2h and simulated intestinal fluid (pH 6.5) for 6h showed no significant change. The in vitro release study showed that DTX-loaded MPP/TPGS/CSO-SA MPMs exhibited slower release characteristics compared to DTX solution. The oral bioavailability of the DTX-loaded MPP/TPGS/CSO-SA MPMs was increased by 2.52 times compared to that of DTX solution. The current results encourage further development of DTX mixed polymeric micelles as the oral drug delivery system. (C) 2013 Elsevier B.V. All rights reserved.