Phospholipid complex as an approach for bioavailability enhancement of echinacoside

Context: Echinacoside (ECH) has been shown to possess a multitude of pharmacological activities, however, oral administered ECH failed to fulfill its therapeutic potential due to poor absorption and low bioavailability. Thus, there is a pressing need to develop a new oral dosage form to enhance its intestinal absorption and improve bioavailability. Objective: The aim of this study was to formulate ECH into phospholipid complex (phytosome, PHY) to enhance intestinal absorption and oral bioavailability of ECH in vivo.Methods: The PHY was prepared by a solvent evaporation method and was characterized by differential scanning calorimetry (DSC) and infrared spectroscopy (IR), and then the physicochemical properties, intestinal absorption and bioavailability of the PHY were investigated. Results: Compared with the physical mixture (MIX) or ECH alone, the n-octanol/water partition coefficient (P) determination results showed that the lipophilicity of ECH was significantly enhanced by formation of PHY. Accordingly, the intestinal absorption rate (K-a) was improved to 2.82-fold and the effective permeability coefficient (P-eff) increased to 3.39-fold. The concentrations of ECH in rat plasma at different times after oral administration of PHY were determined by HPLC. Pharmacokinetic parameters of the PHY in rats were T-max=1.500h, C-max=3.170mg/mL, AUC(0-infinity)=9.375mg/Lh and AUC(0-24)=7.712mg/Lh, respectively. Conclusions: Compared with ECH alone or the MIX group, the relative bioavailability of ECH was increased significantly after formulation into PHY (p<0.05). This might be mainly due to an improvement of the absorption of PHY.