Development of liquiritigenin-phospholipid complex with the enhanced oral bioavailability

In the present study, liquiritigenin-phospholipid complex (LPC) was developed and evaluated to increase the oral bioavailability of liquiritigenin. A single-factor test methodology was applied to optimize the formulation and process for preparing LPC. The effects of solvent, drug concentration, reaction time, temperature and drug-to-phospholipid ratio on encapsulation efficiency were investigated. LPCs were characterized by UV-visible spectroscopy, differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR), and powder X-ray diffractometry (PXRD). The apparent solubility and n-octanol/water partition coefficient were tested. The pharmacokinetic characteristics and bioavailability of the LPC were investigated after oral administration in rats in comparison with liquiritigenin alone. An LPC was successfully prepared. The optimum level of various parameters for liquiritigenin-phospholipid complex was obtained at the drug concentration of 8 mg·mL^-1, reaction time for 15 min, reaction temperature of 30 ℃, a ratio of 1∶4.5 (W/W) drug-to-phospholipid and anhydrous ethanol as reaction solvent. Compared to liquiritigenin, the AUC_0-t of the LPC was increased by 239%. The liquiritigenin-phospholipid complex significantly increase the lipid solubility and bioavailability of liquiritigenin, suggesting that it is an effective formulation for further development and clinical applications.