Objective: To prepare dl-tetrahydropalmatine multivesicular liposomes

investigate its in vitro release property and pharmacokinetics in rats. Method: HPLC was adopted to determine the plasma concentration of dl-tetrahydropalmatine with mobile phase of methanol-(KH2PO4-NaOH buffer salts

pH 6.0) (45: 55)

flow rate of 0.9 mL·min-1 and detection wavelength at 280 nm.dl-Tetrahydropalmatine multivesicular liposomes were prepared by multiple emulsion method

its shape

particle size and in vitro release characteristics were evaluated.Pharmacokinetics were evaluated in rats following intramuscular injection of dl-tetrahydropalmatine multivesicular liposomes or the reference drug of dl-tetrahydropalmatine injections. Result: Particle sizes of these prepared multivesicular liposomes were even and 80% of them were well-distributed in the range of 15.0-30.0 μm.Encapsulation efficiency was more than 88.47%

in vitro cumulative release was more than 80% in 72 h.Main pharmacokinetic parameters of dl-tetrahydropalmatine injections and multivesicular liposomes were as follows:t1/2 of (3.09±0.37)h and (33.97±4.78)h

Cmax of (289.05±30.37)μg·L-1 and (68.34±8.72)μg·L-1

Tmax of (0.93±0.15)h and (3.92±0.43)h;the same parameter of these two preparation had significant differences by intercomparison. Conclusion: This optimized preparation technology is feasible with good reproducibility

dl-tetrahydropalmatine multivesicular liposomes shows a significant sustained-release property.