Phospholipid complex as an approach for bioavailability enhancement of echinacoside

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.

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.

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.

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 (Ka) was improved to 2.82-fold and the effective permeability coefficient (Peff) 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 Tmax = 1.500 h, Cmax = 3.170 mg/mL, AUC0-∞ = 9.375 mg/L h and AUC0-24 = 7.712 mg/L h, respectively.

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.