Mechanisms of oral absorption improvement for insoluble drugs by the combination of phospholipid complex and SNEDDS

摘要

In the present study, a water insoluble drug named silybin was encapsulated into self-nanoemulsifying drug delivery system (SNEDDS) following the preparation of silybin-phospholipid complex (SB-PC), then several methods were carried out to characterize SB-PC-SNEDDS and elucidate its mechanisms to improve the oral absorption of SB. Using a dynamic in?vitro digestion model, the lipolysis of SB-PC-SNEDDS was proved to be mainly related with the property of its lipid excipients. SB-PC-SNEDDS could significantly enhance the transport of SB across Caco-2 cells, which may partly attribute to the increased cell membrane fluidity and the loss of tight junction according to the analysis results of fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) and tight junction protein (ZO-1). The result of in situ perfusion showed the intestinal absorption of SB from high to low was SB-PC-SNEDDS, SB-PC, and SB. The extent of lymphatic transport of SB-PC and SB-PC-SNEDDS via the mesenteric duct was 12.2 and 22.7 folds of that of SB, respectively. In the lymph duct cannulated rats, the relative bioavailability (Fr) of SB-PC and SB-PC-SEDDS compared to SB was 1265.9% and 1802.5%, respectively. All the above results provided mechanistic support for oral absorption improvement of water insoluble drugs by the combination of PC and SNEDDS.