Preparation and pharmacological evaluation of silibinin liposomes

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. The investigation deals with critical parameters controlling the formulation and evaluation of silibinin (silymarin, CAS22888-70-6) liposomes. Small unilamellar liposmal vesicles were prepared using the ethanol injection method. The various formulation and process variables were optimized to improve the drug entrapment efficiency. The study includes the selection of lipid composition, impact of charge imparting agent and the nature of hydration medium. The stability and size parameters were critically monitored. The liposomal systems were also studied for hepatoprotective activity in mice against carbon tetrachloride induced hepatotoxicity and gastroprotective activity using the pyloric ligation method. The results indicate a significant effect of cholesterol on drug-entrapment and drug-leakage characteristics. The size distribution range was from 0.056-1.270 microns with the most frequent size ranging from 0.266-0.466 micron. The amount of drug loaded in these vesicles was approx. 90%. Lipid cholesterol mass ratio of 10:2 has a maximum entrapment of 87.2% (+/- 1.77). The results obtained from the in vivo studies indicate the improved performance of silymarin in liposomes at a level of 55.6% hepatoprotection in comparison to 33.08% of plain drug. Plain liposomes showed hepatoprotection though to a lower degree of 24.2%. Liposomal silymarin and plain liposomes also showed significant antiulcer activity as compared with plain silymarin and control groups.