| Astragaloside IV (ASI), confirmed as the main active ingredient of Radix Astragali, has a favourable therapeutical effect on viral myocarditis. However, the application has been limited by the poor bioavailability of oral administration, low dissolvation in both water and oil, and the danger of hemolysis as a saponin by intravenous injection. To overcome the problems mentioned above, this paper developed a novel traditional Chinese drugs preparation, i.e. Astragaloside IV lipid microsphere injection (ASI-LM). Lipid microsphere (LM) is widely used as water insoluble carriers for drugs, especially for intravenous injection. Drugs are usually incorporated into oil phase or interface of oil phase in LM. So it was presumed to avoid the direct contact with blood vessel and reduce toxicity and stimulus generated by the process of injection. Thus, it shows great advantages.TLC was applied to identify ASI, the crude extract and the purified ASI and ASI standard showed the same dark brown spot at the corresponding position. An HPLC-ELSD method was established for determination of ASI. The retention times of the three compounds mentioned above were identical. The established method is simple, rapid, reliable and suitable for the quality control of purified ASI and ASI-LM.The methods of macroporous resin, n-butanol-macroporous resin and solubility-crystallization are compared to purify the crude extract of ASI, and the result shows that the method of solubility-crystallization could assure the purity (91%) and transfer rate(55%)of ASI. Through orthogonal design combined with single factor inspect and optimize refinement technology, the final refined procedures was as follows:crude extract of ASI was dispersed by 30 times of water→centrifugation→discard supernatant→centrifugation after dispersing the precipitant in 15 times of water (repeat 3 times)→precipitate by methanol→centrifugation→supernatant→remove methanol→white powder. The white powder was the purified ASI.The physico-chemical properties of ASI show the poor solubility in both water and oil. The solubility and apparent oil-water partition coefficient were affected little by pH. At pH7.9, it has lowest solubility and highest apparent oil-water partition coefficient.Due to the poor solubility of ASI in water and oil, the phosphatide complex was prepared to increase the liposolubility. The complex was finally prepared with ASI and phosphatide in dehydrated alcohol at 75℃for 2h, and then the reaction solvent was evaporated to obtain dry residue. High pressure homogenization technique was applied to prepare ASI-LM. The main formulation and preparation factors were systematically investigated, pH, particle size distribution,ζ-potential, content and entrapment efficiency as index. The homogenization conditions, composition of oil phase and emulsifier, pH, and different sterilization modes were optimized.The final formulation and preparation process of ASI-LM was as follows:0.055% ASI and 1.2% phosphatide (EPIKURON 170) (w/w) were added into 30ml dehydrated alcohol, and then heated at 75℃for 2h to prepare the ASI phospholipid complex. As quality percentage, oil phase was composed the complex,5% MCT,5% LCT; the water phase was composed of 2.5% glycerol,0.05% sodium oleate,0.2% F-68,0.1% Tween-80, and 0.01% EDTA-2Na; and the oil phase was added into the water phase to make the coarse emulsion; adjusted the pH to 8.0; the homogenization pressure and cycles were 800bar and 8 times, respectively; then sterilized autoclaving at 121℃for 8 min and then reduced the temperature by ice water bath.The mean diameter of the ASI-LMs prepared in three different lot was 166.3nm and theζ-potential was-29mV, the EE was 89%, the content was 98.2%.Dilution test revealed that the particle size and distribution of the ASI-LM diluted by glucose was relative larger. The samples diluted with sodium chloride injection show good stability. After the dilution 5 or 10 time, the samples were stable for 3 h. So the sodium chloride injection was suggested to use as dilution medium. The particle size and distribution of ASI-LM showed no significant change after 6 months at 25±2℃and 4℃. However, the distribution of the ASI-LM at 25±2℃was little bit larger than those at 4℃, which may caused by coalesence of the small particles. Therefore, it was suitable for ASI-LM to store at 4℃.The safety test showed that the haematolysis index of ASI-LM is less than 5%, indicating ASI-LM caused no rabbit red blood cells in vitro hemolytic, no obvious irritability on rabbit ear vein. The results show that ASI-LM is safe for infusion.A Rapid and accurate UPLC/MS/MS method was established to determine the concentration of ASI in rat plasma. The results showed that both ASI-LM and ASI-S fitted three-compartment model; The main pharmacokinetics parameters analyzed by statistical moment method showed that AUC0-t of ASI-LM and ASI-S were (5155.48±1288.3) and (6266.521±681.0)μg/L*h; t1/2 were (0.858±0.166) and (0.94±0.155) h, there no statistically differences (n=6, P>0.05); their pharmacokinetics curves were similar.
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