Supersaturated polymeric micelles for oral silybin delivery: the role of the Soluplus-PVPVA complex

Increasing the degree of supersaturation of drugs and maintaining their proper stability are very important in improving the oral bioavailability of poorly soluble drugs by a supersaturated drug delivery system (SDDS). In this study, we reported a complex system of Soluplus-Copovidone (Soluplus-PVPVA) loaded with the model drug silybin (SLB) that could not only maintain the stability of a supersaturated solution but also effectively promote oral absorption. The antiprecipitation effect of the polymers on SLB was observed using the solvent-shift method. In addition, the effects of the polymers on absorption were detected by cellular uptake and transport experiments. The mechanisms by which the Soluplus-PVPVA complex promotes oral absorption were explored by dynamic light scattering, transmission electron microscopy, fluorescence spectra and isothermal titration calorimetry analyses. Furthermore, a pharmacokinetic study in rats was used to demonstrate the advantages of the Soluplus-PVPVA complex. The results showed that Soluplus and PVPVA spontaneously formed complexes in aqueous solution the adsorption of PVPVA on the hydrophilic-hydrophobic interface of the Soluplus micelle, and the Soluplus-PVPVA complex significantly increased the absorption of SLB. In conclusion, the Soluplus-PVPVA complex is a potential SDDS for improving the bioavailability of hydrophobic drugs.

Absorption-enhancing mechanisms and advances of polymer-based supersaturated drug delivery system / 药学学报

Supersaturated drug delivery systems (SDDS) are defined as systems that are able to generate and maintain a sustained drug supersaturation in the gastrointestinal tract, facilitating the oral absorption of drugs with poor water solubility. Supersaturated drug solution is generated from a higher energy form of the drug or rapid dissolution through various formulation options. However, supersaturated solution is a thermodynamically unstable system that can easily lead to drug precipitation, missing the aim of improving the absorption. Therefore, maintenance of the supersaturated state is essential for the development of SDDS. Polymer-based SDDS take polymers as the precipitation inhibitor,which can effectively prevent the precipitation of drugs, generating an excellent effect on maintenance of the stability of supersaturated solution. However, different polymers have distinct anti-precipitation ability, and the mechanisms of such activity supported by the polymer remain unrevealed. In this review, we summarize the research advances in the absorption-enhancing mechanisms and in vitro evaluations of polymers-based SDDS. This review provides a reference for the design of rational SDDS.