Preparation And Preliminary Studies On Gambogic Acid Nanosuspensions

Gambogic acid is a natural compound which has significant anti-tumor activity.It has inhibiting effect to against human gastric cancer and human lung adenocarcinoma et al.Gambogic acid is a multitargeted apoptosis-inducing agents of tumor cell,and its mechanisms include inhibition of DNA synthesis in vivo,inhibition of tyrosine kinase phosphorylation and other mechanisms to exert its anti-cancer effects.During gambogic acid nanosuspension preparation,the influence factors which include preparation method,pressure and cycle of homogenization were all studied.In prescription screening aspect,dosages of stabilizer and ethanol were also studied.A series of experiments had been implemented to determine the optimized formulation as follows.Firstly,30 mg gambogic acid was dissolved in 1 mL ethanol and then 24 mg Poloxamer 188 and 25 mg lecithin were dispersed in 50 mL purified water in an ice-water bath.The ethanol solution and aqueous phase were mixed and stirred for 20 min.The mixture was sheared for 5 min at a stirring speed of 20000rpm to obtain a primeval gambogic acid nanosuspension.The primeval gambogic acid nanosuspension was further homogenized with a microfuidizer,performing 3cycles at 5460 psi,and then 12 cycles at 11650 psi to obtain the final gambogic acid nanosuspension?GA-NS?.Nanosuspension is not thermodynamically stable,so the optimized GA-NS was transformed into dry powders by freeze-drying in order to improve the storage stability.The freeze-drying processes have been optimized by examining the color,appearance,redispersibility and other indicators.The final freeze-drying processes are as follows.Firstly,10%mannitol was dispersed in 1 mL GA-NS solution and dissolved by stirring.Then the mixture were rapidly cooled down at-80oC by Ultralow Temperature Freezer for 24 h and at last freeze-dried for 8 h at-60oC.Preparations properties evaluation results were as follows:mean size of particle was about 250 nm,potential of Zeta was more than+20 mV.The shape of GA-NS under TEM is uniformly spherical and the shape of freeze-dried GA-NS powder was virgate from SEM.Compared with gambogic acid,the GA-NS has more regular and uniform shape.DSC results show that a series of preparation process did not affect the crystal of gambogic acid.In this paper,UPLC was used to determine content of gambogic acid in plasma samples.Gambogic acid suspension?GA-S?was selected as the reference.The pharmacokinetics were researched after intravenous injection of GA-S and GA-NS.Compared with GA-S,pharmacokinetic parameters exhibited that the relative bioavailability in mice after intravenous injection of GA-NS increased.The AUC_0–?of GA-S and GA-NS were 195.127 and 356.215?g/mL·h respectively.MRT of GA-NS was significantly longer than the GA-S.GA-NS prolonged retention time in vivo.It indicated that GA-NS effectively increased the bioavailability of GA,prolong retention time of action and enhanced efficacy.The tissue distribution studies indicated that in the liver,AUC,AUQ and MRT of GA-NS all have been increased compared with the solution group and GA-S.According to r^Ce,the order descending as:liver>lung>kidney>spleen>heart.r^Cee and r^Qee showed gambogic acid had liver-targeting characteristics.It was worth noting that GA-NS decreased the gambogic acid concentration and retention time in the heart,so the GA-NS would reduce the side effects.The study results of this paper provided a guideline for the development of the insoluble anti-cancer drugs,and they are importance and significance for clinical applications of gambogic acid.