Study Of Silybin Solution For Intravenous Administration Based On Lipid Emulsion

Silybin(SLB) has a wide range of pharmacological activity, especially the hepatoprotective activity. However, the listed silybin preparations are oral, and the bioavailability is low. So the pharmacological effects can’t be shown completely, and it can not show it’s real level in therapy. In recent years, many silybin injections have been trying. However, no one has been listed because of low drug loading, poor encapsulation efficiency, poor stability and safety, and so on. The objective of this research is to prepare a silybin injection based on lipid emulsion to overcome the shortcoming of low bioavailability. The silybin injection is made of silybin solution and lipid emulsion. It will distribute the drug solution in the lipid emulsion to form a relatively stable dispersion when used. And it is to evaluate the characteristics in vitro and in vivo after the preparations being completed. This article mainly includes the following sections:First, study the prescription of the silybin solutionFirstly, it is to select the best solvent from the most common injectable solvents—ethanol, propanediol and PEG400by using the distribution stability of Silybin in lipid emulsion as the index. The results show that the SLB-PEG400solution is more stable than SLB ethanol and SLB propanediol solution when distributed in lipid emulsion by the same concentration. So we decide to use the PEG400as the solvent of silybin. Secondly, it is to select the concentration of SLB-PEG400and the quantity of pH regulator—citric acid by using the distribution stability of SLB-PEG400in lipid emulsion as the index. The results indicate that the SLB-PEG400with10mg/mL SLB shows better distribution stability than the higher concentration. And if we reduce the concentration lower, it will need more quantity of PEG400to get the same amount of SLB, which will damage the lipid emulsion. So we determine the concentration of SLB-PEG400is10mg/mL. The distribution stability of SLB-PEG400is better when citric acid is added. When the quantity is0.5%, the stability increases obviously. Silybin lipid emulsion(SLB-LE) with0.5mg/mL SLB can stabilize8h at25℃, which is enough to be used in clinic. And the stability can’t increase any more with the quantity of citric acid increasing continually. So we intend the quantity of citric acid in the SLB-PEG400solution is0.5%. Therefore we decide the prescription of100mL SLB solution is1.00g SLB and0.50g citric acid, add PEG400to100mL.Second, prepare SLB-PEG400solution and evaluate its stabilityPrepare the SLB-PEG400solution according to the result of prescription study. And the content of SLB is used as index to verify the preparation technology. The result shows the technology is feasible and repeatable. Then the content of SLB, pH and appearance are used as indexes to evaluate the stability of SLB-PEG400solution. The results show the sterilization stability is good, and light has no obvious effect on it. But the content of SLB decreases slightly with time at high temperature. The content of SLB decreases by about5%at40℃after six months. The accelerated stability at30℃and long-term stability at25℃is relatively good, and the content decreases by less than5%. The pH and appearance of the solution don’t have any change. So SLB-PEG solution is more stable when stored at low temperature.Third, prepare SLB-LE and evaluate its stabilityDistribute the SLB-PEG400solution to lipid emulsion uniformly to get the SLB-LE with0.4mg/mL or0.5mg/mL SLB respectively. Then use the content of SLB, particle size pH and appearance as indexes to evaluate the distribution stability further. The content at Oh is acted as100%. Take samples with time, and detect the content of SLB after filtering and dissolving. And detect the particle size and pH, observe the appearance. The results show the stability time of SLB-LE with0.4mg/mL and0.5mg/mL SLB is14h and8h respectively. It can clearly be seen that the content of SLB in the SLB-LE has obvious effect on its stability.Forth, study the release in vitro and phase distribution of SLB-LEThe phosphate buffer pH7.8-8.0with0.5%SDS or10%ethanol are used as the release media to study the release of SLB-LE in vitro. The results show the cumulative release rate reaches to about80%in6h in each media, and more than90%in10h. Ultracentrifugation is used to study the phase distribution. After the water phase, oil phase and emulsion layer are separated, detect the content of SLB in water and oil phase respectively, and calculate the content in emulsion layer. The results show SLB is mainly distributed in emulsion. And the SLB-LE with0.4mg/mL or0.5mg/mL SLB don’t have obvious difference. The SLB in emulsion layer is more than80%, and seldom in oil and water, especially in water.Fifth, evaluate the safety of SLB-LEWe evaluate the safety, irritation and acute toxicity of SLB-LE according to the guiding principles of hemolysis test, irritation test and acute toxicity test to intend the experimental programs. And then we judge the result by using the method in guiding principles. Test results show SLB-LE will not lead to hemolysis and cruor. The administration sites don’t appear any pathological damage. The mice don’t show any toxicity reaction at the biggest dosage that can be reached. So we can judge the safety of SLB-LE is good preliminarily according to these results.Sixth, study the pharmacokinetic and tissue distribution of SLB-LE In order to know the metabolism of SLB-LE, we study the pharmacokinetic and tissue distribution. The result of pharmacokinetic shows the half-life of SLB-LE in rat is about0.6h, and AUC is1.232μg·h·mL-1. And the tissue distribution result shows SLB is mainly distributed in liver and kidney. But it removes more quickly in kidney. The AUC is9.3272μg·h·mL-1in liver, which is the biggest.