Objective: To prepare ursolic acid liposome

optimize formulation of ursolic acid liposome and investigate its physicochemical properties and in vitro release behavior. Method: Oil-water partition coefficient of ursolic acid in a series of phosphate buffer solutions of different pH by shake flask method;Ursolic acid liposome were prepared by film-ultrasonic dispersion method

with entrapment efficiency as index

formulation of ursolic acid liposome was optimized by orthogonal test.Morphology was examined by transmission electron microscope

particle size and zeta potential were determined by laser particle sizer/zeta potential system

in vitro release behavior of ursolic acid liposome was studied by dynamic dialysis. Result: Oil-water partition coefficients of ursolic acid lgPO/W decreased with increasing of pH

and they were >0.5

it suggested that ursolic acid had good lipophilic.Optimized formulation was:drug loading of 6 mg

phospholipid-cholesterol 2: 1

the molar concentration of PBS 0.01 mol· L-1

ultrasonic time 3 min.These prepared ursolic acid liposome were spherical or elliptical sphere under transmission electron

the mean particle size was (223.7±68.4) nm

zeta potential was -20.63 mv

entrapment efficiency was (89.85±1.66)%

in vitro release behavior fitted the first order kinetic model

in vitro cumulative release rate was >80% in 48 h. Conclusion: Prepared ursolic acid liposome had high entrapment efficiency and good in vitro release property with sustained release characteristics.