Preparation And In Vivo And In Vitro Evaluation Of Oxaliplatin Liposomes

As the third generation platinum antineoplastic agent after Cisplatin and Carboplatin,Oxaliplatin is mainly used in the treatment of advanced colorectal cancer,and also have anti-tumor activity for variety tumor cell lines.However,peripheral neuropathy limited its clinical use.Liposomes can improve absorption,reduce side effect,enhance targeting,so it became a hot research for drug carriers.The thesis presented here focuses mainly on establishment of methodology of Oxaliplatin liposomes, preparation of Oxaliplatin liposomes,and quality evaluation in vitro and in vivo,which may be divided into four parts.Part one:ReviewThe advanced progresses of novel liposomes and Oxaliplatin are described,including physico-chemical properties and the mechanism of antitumor,the novel forms and new preparation of Oxaliplatin,which of course,may be regarded as a basis for our succeeding research.Part two:The establishment of in vitro and in vivo analytical method of Oxaliplatin liposomesFree Oxaliplatin and the Oxaliplatin encapsulated in liposomes can be well separated by Sephadex column chromatography methods and then determinated by HPLC methods.Methodological study results showed: regression equation of working curve:A=7068.9C-1775.8（n=7, r=0.9998）,linear range:0.2-100μg/ml,intra-day and inter-day precision were less than 2%,the stability of drug was fine in 24h,method recovery of HPLC was 99.61%～100.54%;Sephadex column chromatography in the column recovery was 97.27%～101.68%. Because the HPLC method can’t satisfy the requirements of oxaliplatin in vivo analysis,so we established the Inductively Coupled Plasma Optical Emission Spectrometry method（ICP-OES method） and chosed the more moderate sample digestion method.The method recovery was 94.99%～105.01%,linear relationship was good.Part three:Preparation of Oxaliplatin liposomes and preliminary study of freeze-dried productOxaliplatin liposomes were prepared with Reverse-phase evaporation method.Many single factors which may influence the appearance,encapsulation efficiency and stability of liposome preparation were observed in a large scale,such as drug and phospholipids ration,phospholipids and cholesterol ration,the ratio of oil to water phase,the ratio of different solvents and the temperature.The optimization formula was got after orthogonal experiment about principal influential factors.The detail was below:drug:lipid=1:12,lipid: cholesterol=4:1,ethanol:chloroform=5:4,water bath temperature at 40℃. From the view of appearance of freeze-dried preparations and the difficulty of water dispersion,we have chosen trehalose as freeze-drying protectant.Part four:In vitro quality evaluation of Oxaliplatin liposomesWe observed many indexes to evaluate the quality of oxaliplatin liposome in vitro,such as the morphology,particle size,pH value, encapsulation efficiency,release profile,stability and so on.The results indicated that the preparation of liposome has small particle diameter, high encapsulation efficiency,and no break release phenomenon.The preparation was stable at 4℃in 3 months,leaking only a few drugs after diluted to 250ml.It proved that the preparation has a fine stability.Part five:Pharmacokinetics study of Oxaliplatin liposomes in ratsDistribution of Oxaliplatin control preparation,Oxaliplatin liposomes were studied by ICP-OES method in rats.The pharmacokinetics date was calculated with compartment and non-compartment model.After statistical analysis,we got the result that the in vivo behavior of Oxaliplatin liposomes and Oxaliplatin solution both complied with the two compartment model.With the same dosage（20mg/kg） in rats by i.v,the t_1/2α、t_1/2β、AUC _0-τof Oxaliplatin liposomes were 56.539h、169.618h and 199.972 hμg/ml,which 18.691、18.689、7.79 times those Oxaliplatin solution,mean residence time was longer.Part six:Biodistribution study of Oxaliplatin liposomes in ratsDistribution of Oxaliplatin control preparation,Oxaliplatin liposomes were studied by ICP-OES method in rats.The biodistribution in vivo results showed that 0.5h after i.v.the free drug was detected in blood, liver,spleen,kidney and heart,comper with Oxaliplatin solution, Oxaliplatin liposomes in blood,liver,spleen,lung were much higher, equivalent in heart,and less in kidney.The increased amount of lipsomes in the liver and lung indicated a possibility for lipsomes to be developed into liver or lung targeting drug delivery system.