The preparation and investigation of spinosin-phospholipid complex self-microemulsifying drug delivery system based on the absorption characteristics of spinosin

OBJECTIVES: The aim of this research was to investigate the intestinal absorption characteristics and mechanisms of spinosin (SPI), and a new dosage form was prepared to increase the intestinal absorption of SPI. METHODS: In this study, the intestinal absorption characteristics and mechanisms of SPI were first investigated using in situ absorption model and Caco-2 monolayer model. Subsequently, the phospholipid complex (PLC) loaded with SPI was prepared followed by a self-microemulsifying drug delivery system (SMEDDS) technique for developing a more efficient formulation. KEY FINDINGS: The results showed that the absorption rate constant (0.02 h-1 ) and absorption percentage (10%) of SPI were small. Paracellular and active transport pathways mainly mediated the intestinal absorption of SPI. Moreover, SPI-PLC-SMEDDS showed a nanoscale particle size and excellent dispersibility in vitro. The cellular uptake and transportation properties of SPI-PLC-SMEDDS in the Caco-2 cell model were improved significantly. Besides, a statistically dramatically higher oral bioavailability (almost fivefold) was observed following the oral administration of SPI-PLC-SMEDDS than free SPI on the basis of pharmacokinetic experiment results. Furthermore, the SPI-PLC-SMEDDS exhibited certain immunization. CONCLUSIONS: SPI-PLC-SMEDDS could be a promising oral drug delivery system to improve the absorption of SPI.