Objective: To prepare oleanolic acid nanoliposomes and investigate its in vivo pharmacokinetics behavior in rats. Method: Oleanolic acid nanoliposomes were prepared by reverse-phase evaporation and characterized

entrapment efficiency was determined by sephadex column chromatography.Rats were injected with oleanolic acid nanoliposomes and oleanolic acid solution prepared by ourselves via the tail

respectively.The plasma concentrations of oleanolic acid from samples were determined by HPLC

with protopanaxadiol as internal standard.Pharmacokinetic parameters and non-compartment models were analyzed by t-test and PK-Slover 2.0 software

respectively. Result: Oleanolic acid nanoliposomes were round or oval vesicles with the mean diametre of (98.11±0.32) nm and encapsulation efficiency of (81.2±1.21)%.The plasma concentration-time curves of the nanoliposomes and solution conformed to non-compartmental model.By comparing with oleanolic acid solution

t1/2 and MRT of oleanolic acid nanoliposomes extended

AUC0-t increased and CL_obs decreased. Conclusion: Oleanolic acid nanoliposomes with high entrapment efficiency and small particle size had significantly improved bioavailability of oleanolic acid and prolonged its in vivo retention time.