Doxorubicin Loaded Micelle For Oral Delivery And Tumor Targeting

Doxorubicin（Doxorubicin,DOX）is a broad-spectrum chemotherapy drugs,and all currently marketed preparations are injections.The oral route of administration has certain advantages compared with the intravenous route,which is reflected in lower psychological trauma、better patient compliance and lower medical resource consumption.However,oral administration of chemotherapeutic drugs,such as doxorubicin,face absorption barriers,including the efflux of p-glycoprotein in the intestinal epithelial cell layer,which results low oral bioavailability.Micelle prepared with specific excipients,such as vitamin E polyethylene glycol succinate（D-α-Tocopherol polyethylene glycol 1000 succinate,TPGS）,can effectively inhibit the efflux of multidrug resistance proteins and improve the oral absorption of the chemotherapeutic drugs contained.Tumor targeting of chemotherapeutic drugs after oral absorption is also a key to enhance oral absorption and reduce toxicity,but such issues are currently seldom studied.The folic acid（Folic acid,FA）modification strategy has been proven to improve the oral absorption and tumor targeting of injectable drugs,but there is no report to improve tumor targeting after oral administration.Therefore,in terms of the issues discussed previously,this paper designs an acid-modified micelle（DOX@FA-PEG-DSPE/PEG-DSPE/TPGS Micelle,DOX@FPT Micelle）for oral administration,that can promote oral absorption and improve tumor targeting at the same time.The effects of micelle on promoting the oral absorption of doxorubicin and tumor distribution are evaluated in vivo and in vitro.The main research content and conclusions of this article are as follows:（1）The preparation method of doxorubicin loaded micelle was studied,which included one-step method、melting method and thin film hydration method.The optimal preparation method was finally determined as the thin film hydration method.Then the process optimization of the film hydration method was carried out,and the best process of the film hydration method was obtained:hydration time is 30 min,hydration temperature is 40℃,hydration stirring speed is 300 rpm.The doxorubicin-loaded micelle(DOX@F_5%P_75%T_20%Micelle)prepared under this optimal process had a particle size of 14.3±0.4 nm,a PDI of 0.089±0.034,a drug loading efficiency of 6.9%±0.3%,drug encapsulation efficiency of74.3%±3.4%.（2）To study the proportion of doxorubicin loaded micelle.Through the investigation of human colon adenocarcinoma cell（Caco-2）monolayer uptake、micelle placement stability and critical micelle concentration（Critical micelle concentration,CMC）,the mass ratio of TPGS in the micelle was optimized to 20%.The micelle was determined as DOX@F_5%P_75%T_20%Micelle（5%FA-PEG-DSPE,75%PEG-DSPE,20%TPGS,W/W）.The micelle was studied for release behavior in simulated gastrointestinal fluid,which showed that the doxorubicin-loaded micelle(DOX@F_5%P_75%T_20%Micelle)only released25%of doxorubicin in the simulated gastrointestinal fluid for 4 hours,indicating the micelle can protect most of the doxorubicin loaded in it from leaking when passing through the main absorption site of the gastrointestinal tract.（3）The oral bioavailability and tissue distribution of doxorubicin-containing micelle(DOX@F_5%P_75%T_20%Micelle)was studied.The oral bioavailability and pharmacokinetic behavior of doxorubicin in SD rats after a single dose of DOX@F_5%P_75%T_20%Micelle was investigated,and the absorption promotion effect of micelle was evaluated in vivo.Then the accumulation of doxorubicin in tumors and major organs after a single intragastric administration of DOX@F_5%P_75%T_20%Micelle for H22 hepatocarcinoma tumor-bearing Balb/c mice was studied.Experiments showed that compared with doxorubicin solution,DOX@F_5%P_75%T_20%Micelle has a 250%increase in oral bioavailability and a significantly lower clearance rate.DOX@F_5%P_75%T_20%Micelle had a significantly higher tumor targeting ability after oral administration than the micelle group that was not modified by folic acid.（4）The oral pharmacodynamics and safety of DOX@F_5%P_75%T_20%Micelle was studied.The tumor growth rate of H22 hepatocarcinoma-bearing Balb/c mice after multiple intragastric administration of DOX@F_5%P_75%T_20%Micelle was investigated,and the tumor weight of each group of tumor-bearing mice at the end of the experiment was measured.H&E staining of tumor was performed to evaluate the effect of tumor suppression at the end of the experiment.The body weight changes of mice during the experiment and H&E staining of main organs at the end of the experiment were studied to evaluate the biological safety of doxorubicin-loaded micelle.Experiments showed that DOX@F_5%P_75%T_20%Micelle had a significantly higher anti-tumor effect than doxorubicin solution and micelle that was not modified by folic acid,with an anti-tumor rate of 52%.Compared with intravenous injection of doxorubicin,DOX@F_5%P_75%T_20%Micelle had higher biological safety.In summary,this article focuses on the oral bioavailability of doxorubicin and the target distribution in vivo after oral administration,and designed an oral tumor-targeted micelle loading doxorubicin(DOX@F_5%P_75%T_20%Micelle).The micelle improves the oral absorption of the anti-cancer drug doxorubicin,and has a better targeting effect on tumors.