Studies On Silybin Liposomes

Silybin (SLB) is the major active constituent of silymarin, the mixture of flavonolignans extracted from blessed milk thistle (Silybum marianum). It is used in the treatment and prevention of liver diseases because of its hepatoprotective (antihepatotoxic) properties. Clinical tests have also shown its ability to prevent and treat cirrhosis, chronic hepatitis, and gall bladder problems. Silybin dihemisuccinate is the derivant of silybin, it is reported that it converted to silybin to bring the therapeutical effect. The aim of the present study was to encage a drug into liposomal structures to make them more effective, safe and targeted to liver cells.HPLC methods have been developed fot analyzing the content of silybin dihemisuccinate. The methods of ultra filtration were developed to determine the encapsulation efficiency. Considering the properties of the drug, liposmal vesicles were prepared using the ethanol injection method. The various formulation and process variables were optimized to improve the drug entrapment efficiency. Appearance, effect of drug loading, entrapment efficiency, average particle size and size distribution, zeta potential, stability with Normal Saline, osmotic, hemolysis have been tested. And valued stability according to effect of drug loading, entrapment efficiency, pH value and particle size. Liposome is thermodynamic instability system, the impacts of lyophilization process and lyo-protectant on the freeze-dried product were studied, with the appearance, particle size and encapsulation efficiency after reconstituted as index. Optimized freeze-drying process and value the products. The in-vitro analyzing method of silybin liposome was established. The liposomal systems were also studied for PK parameters in rat using tail vine injection. Value test samples compared to reference preparation.Content and EE of silybin and silybin dihemisuccinate meet methodological requirements. The signal factor study showed : silybin concentration was 0.3 mg/mL, lipid concentration was 6 mg/mL, while the ratio of lipid to cholesterol (g/g) was 10 : 1. And the procedure should be dissolve lipid, cholesterol and silybin into pure ethanol, and the preparation temperature was 35℃. The optimized preparation process and formula were as follows : the drug-lipid ratio (w/w) was 1 : 20, buffer pH was 5.70, concentration of drug was 0.10 mg/mL, it took 20 min to dissolve the issues. Silybin liposome was emulsion white, contained drug 188μg/mL±8μg/mL、897μg/mL±10μg/mL, respectively, EE were determined to be 89.44%±1.28%、51.46%±0.99%, respectively, average size was (160±23) nm, zeta potential of (-18.6±1.2) mV, Normal Saline pH of 5.79. with good stability and osmotic and no hemolysis. Prepared silybin liposome freeze-dried product, determined the ratio of lipid to mannitol was 1∶3, or lipid / mannitol / trehalose (1∶1.5∶1.5, g/g/g), added protection of free-dried into liposome solution. The optimized freeze-drying process was as follows : freezing temperature was -70℃, freeze rapidly and freezing time was 5 h, drying time was 32 h. The investigation on freeze-drying products showed that there were no obvious changes with liposome in particle size, encapsulation efficiency and pH before and after freeze-drying, no hemolysis. Accelerating stability test show that liposome freeze-drying products were stable at the temperature of 25℃±2℃and relative humidity of 60%±10% for 1 month. PK. results indicate significant different activities compared to injection prodects.So, Good formula and preparation process were done to prepare silybin liposome using the ethanol injection method. which showed high EE, good particle size and size diffusion, negative zeta potential and no hemolysis. Meet vein injection requirements. And free-dry products could get good samples after dispersible.