Objective: To investigate effect the of phospholipids composition on tissue distribution characteristics of brucine in stealth liposomes containing total alkaloids from Strychni Semen. Method: Liposomes containing total alkaloids from Strychni Semen were prepared by ammonium sulfate transmembrane gradients and stealth liposome technique.Contents of total alkaloids and brucine in liposomes were determined and compared after free drug was removed.After intravenous administration of total alkaloids solution or stealth liposomes with different composition

tissue and plasma samples were drawn at different intervals and the concentration of brucine were determined by a validated HPLC method. Result: Ratio of brucine to total alkaloids in liposomes

in the range of 26%-31%

hardly varied with phospholipids composition.Compared with soybean phosphatidylcholine (SPC) stealth liposomes

after intravenous administration of stealth liposomes composed of both hydrogenated soybean phosphatidylcholine (HSPC) and SPC

the concentration of burcine in small intestine and plasma at 5 min were significantly increased 1.34-fold and 2.35-fold

respectively.Moreover

following administration of HSPC stealth liposomes containing total alkaloids

plasma concentration of brucine was much higher than other liposomes.Compared with SPC liposomes

plasma concentration of brucine at 5 min increased by 8.52-fold.In addition

brucine concentration in spleen

lung and heart were also significantly increased and those in small intestine were significantly reduced. Conclusion: Phospholipids composition is the key factor which influences tissue distribution of brucine after intravenous administration of stealth liposomes containing total alkaloids from Strychni Semen.