Study On Cisplatin Magnetic Solid Lipid Nanoparticles

According to USP27,an in vitro HPLC method was established to determine the concentration of CDDP in our work.With a column of Lichrospher-NH₂ and a quaternary system of ethyl acetate-methanol-DMF-purified water（25:16:5:5）as mobile phase,this method was analysed at a wavelength of 310 nm,and was proved to be quick,simple and had high precision and recovery.The equilibrium solubility,oil/water partition coefficient and stability of CDDP were determined,and the results showed that CDDP was stable at pH 3～6 in PBS,while was instable when exposed in light and heat.The effects on the appearance and stability of CDDP-SLN of processes and formulations were investigated by single factor experiments.The optimal formulation was obtained by orthogonal experiment design,based on the encapsulate efficiency（EE%）.The Fe₃O₄ magnetic fluid,which was synthesised by co-precipitation method,was added in the formulation.The Magnetic Solid Lipid nanoparticles loaded CDDP（CDDP-MSLN）was finally acquired with the method of emulsification dispersion-ultrasound,with glycerin monostearate as lipid carrier,soybean phospholipid for injection,Pluronic F-68 and Tween80 as emulsifiers.CDDP-MSLN possessed a small size and an uniform particle size distribution,which were consistent with the demand of nano-preparations.Many pharmaceutical characteristics of CDDP-MSLN were investigated.The appearance was examined by transmission electron microscopy（TEM）;The size,distribution and zeta potential were measured by laser size analyser and potential detector,individualy;The crystal forms of formulation were determined by X-ray diffractometer;The saturation magnetization was measured by vibration sample magnetometer（VSM）.The microcolumn centrifugation method was applied to determined the EE%of CDDP-MSLN.In addition,an HPLC method for the assay of release of CDDP from CDDP-MSLN was established,and then,its in vitro release behaviour and stability were investigated.The results showed that CDDP-MSLN was sphericity;the average size,zeta potential and EE%were（132±18）nm,（-13.3±6.94）mV and 75.9%,respectively;It was indicated that CDDP was embeded into MSLN with the form of amorphous;Results of release experiments showed that the release of CDDP-MSLN were completely in the given mediums,which was according to Weibull model.Besides,CDDP-MSLN was instable in 4℃and 25℃,therefore,the lyophilized products were necessary for storage.The formulations and processes of lyophilization were investigated base on the appearance, redissolution and redispersibility of CDDP-MSLN.Eventually,10%mannitol was employed as protecting agent after screen of various types and concentrations of cryoprotective agents.The optimal process was as follows:precooled at -74℃for 12 h,primary drying at -25℃for 14 h, secondary drying at 10℃for 2 h,then freeze-dry powder of CDDP-MSLN was obtained.A pre-column derivatization HPLC method was established for the in vivo assay of CDDP. Nickel chloride and diethyldithiocarbamate（DDTC）were employed as internal standard and derivatization agent,respectively.This method was proved to be specified and precised,which was fit for the in vivo assay of CDDP.Three different formulations,which included CDDP saline solution,CDDP-MSLN and CDDP-MSLN under applied magnetic field,respectively, were administrated i.v.in rats to examine their in vivo distributions.We can reach to a conclusion that CDDP-MSLN was able to gather to targeted areas and exhibited an obvious targeted effect under applied field,therefore the physical targeted effects were finally achieved.