Design and evaluation of a novel evodiamine-phospholipid complex for improved oral bioavailability

A novel evodiamine (EVO)-phospholipid complex (EPLC) was designed to improve the bioavailability of EVO. A central composite design approach was employed for process optimization. EPLC were characterized by differential scanning calorimetry, ultraviolet spectroscopy, Fourier transformed infrared spectroscopy, (1)H-NMR spectroscopy, matrix-assisted laser desorption/ionization time-of-flight spectroscopy, apparent solubility, and dissolution rate. After oral administration of EPLC, the concentrations of EVO at different time points were determined by high-performance liquid chromatography. The optimal formulation for EPLC was obtained where the values of X (1), X (2), and X (3) were 2, 0.5, and 2.5 mg/mL, respectively. The average particle size and zeta potential of EPLC with the optimized formulation were 246.1 nm and -26.94 mV, respectively. The EVO and phospholipids in the EPLC were associated with non-covalent interactions. The solubility of EPLC in water and the dissolution rate of EPLC in phosphate-buffered solution (pH 6.8) were substantially enhanced. The plasma EVO concentration-time curves of EPLC and free EVO were both in accordance with the two-compartment model. The peak concentration and AUC(0-∞) of EPLC were increased, and the relative bioavailability was significantly increased to 218.82 % compared with that of EVO.