Sustained oral drug delivery using PEGylated liposomes incorporated into polysaccharide hydrogel formulations

In this study, PEGylated liposomes (PEG-Lip) were combined with polysaccharides to sustain their oral absorption-enhancing effect. PEG-Lip was prepared by the thin-film hydration method and mixed with carrageenan (CGN), xanthan gum (XG), or locust bean gum (LBG). The prepared PEG-Lip had a particle size of ∼100 nm and a zeta potential of approximately -50 mV. The polysaccharide concentrations that did not inhibit PEG-Lip behavior were 0.5% for CGN and 0.25% for XG and LBG. At 25 °C, the release of PEG-Lip from each polysaccharide was generally consistent with its diffusion within the polysaccharide. In the rheological evaluation, only XG3-LBG7, a 3:7 mixture of XG and LBG, exhibited gel-like behavior, whereas the other formulations functioned as viscosity modifiers. Oral administration in rats showed improved gastrointestinal retention compared with PEG-Lip alone. Furthermore, XG3-LBG7 provided the greatest improvement in the oral absorption of FITC-dextran (FD4). These findings suggest that optimizing both PEG-Lip release and the rheological properties of polysaccharides is important for improving oral absorption.