| ObjectiveTo prepare the microemulsion of teriflunomide and to investigate the permeability of the transdermal permeation in vitro.At the same time,establish an accurate and sensitive method for the detection of teriflunomide in plasma samples.The metabolic process and related kinetic parameters of teriflunomide microemulsion in living rats were investigated by this method.So as to provide theoretical reference for the transdermal absorption and follow-up clinical research for the preparation.Methods1.Based on the pseudo-ternary phase diagram,the optimal composition ratio of microemulsion was determined by the shape of the shadow shape of microemulsion,and the stability of the microemulsion was prepared.The percutaneous penetration of drugs was carried out by Franz dispersing device.Comparing the cumulative permeation per unit area（Qn）of aqueous solutions of 0.1%,0.25%teriflunomide microemulsion with 0.1%teriflunomide common emulsion and aqueous solution.2.In combination with the physical and chemical properties of teriflunomide,HPLC was applied to study the drug in plasma samples.,and the chromatographic condition was chromatographic column:ODS C18（250 mm x 4.6 mm,5μm）;Liquid phase:0.01mol·mL-11 phosphate buffer solution（pH=7.4）:methanol=43.8:56.2;column temperature 40℃;detection wavelength of 294.0 nm;internal standard:methyl methacrylate(5.0μg·mL-1).3.The experiment was divided into three groups:teriflunomide percutaneous I group（1.0 mg）,percutaneous II group（2.0 mg）and gavage group（1.0 mg）.Blood was taken at different time points in male SD rats.The concentration of teriflunomide in 3 groups of plasma was measured by HPLC method.The plasma drug concentration time curve was plotted,and the data were treated by DAS 4.0.The pharmacokinetic parameters of3 groups were obtained by statistical moments.4.The rats were divided into three groups:blank control,blank microemulsion and drug（teriflunomide）containing microemulsion.The skin irritation of the different time points was observed by self control,and the score of the skin irritation response score was scored.Results1.The optimal composition of microemulsion contained isopropyl myristate,lecithin,ethanol and water（42.12:21.06:21.06:15.76）.The prepared microemulsion was smooth and stable,with an average particle size of 27.5 to 37.5 nm,and the distribution is concentrated.The Q24h4h of the 4 samples is respectively 157.82,357.76,65.15 and 17.27μg/cm2.2.When using the HPLC method,the peak of teriflunomide and internal standard separation is good,without the interference from other substances in the plasma,The linearity of teriflunomide between 0.3950.00μg·mL-1（R2=0.9991）was better,the lowest detection concentration was 0.15μg·mL-1,The retention time of methyl ester and terflamine was 5 min and 11 min in turn,respectively.In this method,the chromatographic peak has good symmetry,no impurity peak interference,and its accuracy and recovery can meet the needs of the analysis of terflamine plasma samples.3.The main pharmacokinetic parameters of group I（1.0mg）,percutaneous II Group（2.0mg）and gavage group（1 mg）were Tmax（12.41±1.36、12.28±1.47、8.23±1.23）h;Cmax（15.87±0.57、28.82±0.71、47.14±0.65）μg·mL-1;AUC0→60h（756.32±67.54、997.69±94.12、437.27±104.26）μg·mL-1·h;T1/2（41.63±8.41、44.84±10.27、10.73±3.61）h;MRT0→60h（33.46±6.89、47.52±9.35、18.74±4.13）h.4.There was no skin irritation in the blank control group and the blank microemulsion,and the microemulsion was slightly stimulated by the microemulsion.The skin was cleaned after the microemulsion was removed,and the skin returned to normal after the other night.Conclusion1.The preparation of teriflunomide is good for microemulsion stability,suitable for particle size,and strong skin absorption.It is expected to prepare its external microemulsion for clinical use.2.This method is of high sensitivity,easy to operate,high feasibility and widely used in teriflunomide plasma samples.3.Compared with gastric gavage,teriflunomide transdermal drug had a stable concentration and relatively high bioavailability.Compared to the dose of teriflunomide,transdermal absorption was related to the dose of teriflunomide in microemulsion.The higher the dose,the more absorption.4.Transdermal delivery of teriflunomide microemulsion haslittle effect on the skin and does not interfere with its normal function.The preparation of transdermal drug delivery is safe and effective. |
