Danshen-phospholipid complex for improved bioavailability: preparation, in vitro and in vivo evaluations

Object: In order to improve the oral bioavailability of Salvia miltiorrhiza extract (ESM), S. miltiorrhiza phospholipid complex (ESM-PC) was prepared by solvent evaporation. The relative proportions of Salvianolic acid B (Sal B) and Tanshinone IIA (Tan IIA) were investigated using the combination percentage as the standard. The physical and chemical properties of the phospholipid complex were studied by ultraviolet spectroscopy and infrared absorption. Solubility, octanol-water partition coefficient, dissolution rate and in vivo pharmacokinetics were also investigated. Results: ESM-PC with a drug to phospholipid ratio of 1:1 was successfully prepared in methanol at 50°C for 1 h. The determined combination percentage was 55.25% ± 1.04%. Ultraviolet absorption and Fourier transform infrared spectroscopy confirmed the formation of ESM-PC. Relative to ESM, the solubility, octanol-water partition coefficient and in vitro dissolution rate of ESM-PC were improved to varying degrees in a pH-dependent manner. After intragastric administration in rats, the bioavailabilities of Sal B and Tan IIA in ESM-PC were 4.91and 2.49-fold higher than those in ESM. Conclusion: The oral absorption of Sal B and Tan IIA were significantly improved using ESM-PC, mainly due to increased solubility and dissolution rate.