Study On Ursolic Acid Inclusion Compound And Evaluation Of Its Bioequivalence In Rabbit

Ursolic Acid (UA) is pentacyclic triterpenoid compound, which can be widely found in natural plants. It has such biological effects; especially the anti-cancer effect was highlighted in recent years. But for its hydrophobicity,its dissolution and absorption is influenced in gastrointestinal tract. In other words,the character leads to a low bioavailability and inferior curative effect.The object was to study the preparation process of ursolic acid-γ-cyclodextrin inclusion compound for the purpose to increase the solubility and dissolution rate of ursolic acid. The bioavailability and bioequivalence of ursolic acid inclusion compound, solid dispersion and liposome were also evaluated.Various parameters influencing the quality of ursolic acid have been discussed. At last,ursolic acid-γ-cyclodextrin inclusion compounds were prepared by simple grinding with a mortar and pestle of a slurry of drug and cyclodextrin. A rotatable central composite design was applied to predict the effects of the quantitive factors for the optimized formulation.The formation of the inclusion was proved by Differential Scanning calorimeters,IR,X-ray diffractometry and solubility before and after including. The result of DSC indicated that inγ-CD inclusion compounds,ursolic acid existed as an amorphous form andγ-CD inclusion compounds can increase the dissolution rate of ursolic acid significantly.An HPLC method was developed and validated for ursolic acid assay in plasma sample. The mobile phase consisted of acetonitrile -water (80:20, vlv) which contain 7mMγ-CD .The ursolic acidγ-CD inclusion compounds, solid dispersion and liposome were administered orally in a three way crossover study to adult, male rabbits. Blood samples were drawn by venipunture at 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 15, 24h. The blood samples were centrifuged at 3000g for 15 min at room temperature; plasma was separated and kept frozen at -15℃until assayed in 3 days. Plasma concentration was determined by HPLC method. Pharmacokinetic parameters were calculated by DAS 2.0. The bioequivalence of three formulations of ursolic acid was evaluated by variance analysis, two-one side t test and 90% confidential internal to AUC, Cmax and Tmax.Ursolic acid inclusion compound has high encapsulation efficiency. And its solubility and dissolution rate was much improved with comparison of ursolic acid alone. HPLC method has high particularity, high sensibility and high precision. The good validation criteria results of the method and sensitivity allowed its use in pharmacokinetics and bioequivalence study of ursolic acid. The value of AUC, Cmax and Tmax of ursolic acid in vivo of rabbits were greatly increased when compared with ursolic acid alone. The statistical results indicated differences in the three kinds of ursolic acid formulations; we could conclude that the test formulations were not bioequivalent to the reference formulation.