PBPK Modeling Study On The Effect Of Paclitaxel On Pharmacokinetics Of Doxorubicin In Combination With Chemotherapy

Objective:Clinically,DOX and PTX are commonly used in the treatment of breast cancer to enhance the efficacy,with the increase of adverse reactions.In this study,the effects of PTX on the pharmacokinetics and tissue distribution of DOX and its metabolite DOXol were investigated by mouse experiments.The DOX PBPK model of mouse was established by collecting DOX related physical and chemical parameters,physiological parameters and pharmacokinetic parameters,and the accuracy and reliability of the model were verified.Then the PBPK model was extrapolated to the rat and human to predict the pharmacokinetic behavior of DOX.The pharmacokinetic behavior of DOX in DOX and PTX combined chemotherapy was simulated by using the established PBPK model to explore the effect of PTX on the pharmacokinetic behavior of DOX in vivo,and to provide guidance for the clinical dosing regimen of DOX.Methods:1.Establish UPLC-MS/MS method for detecting DOX and DOXol in biological samplesWe optimized the ion source temperature,the cone voltage of each ion to be measured,the capillary voltage and UPLC conditions.The chromatographic conditions and mass spectrometry conditions of DOX and DOXol were determined,and UPLC-MS/MS method for detecting DOX and DOXol in biological samples was established.And a methodological study was performed.2.Effect of PTX on pharmacokinetics of DOX and DOXol in miceA 4T1 tumor-bearing mouse model was established and randomly divided into three groups for tail vein administration:DOX group was administered alone;DOX?PTX group?DOX was given first,and PTX was administered 1 h later?;PTX?DOX group?PTX was given first,and DOX was administered 1 h later?.Plasma and tissue samples were collected at 0.25 h,1 h,4 h,8 h,and 24 h after the end of dosing.In the experiment,DAU was used as an internal standard substance to establish a UPLC-MS/MS method to detect mouse plasma and tissues?including heart,liver,spleen,lung,kidney and tumor?,and to explore the effect of PTX on the pharmacokinetics of DOX and DOXol in combination.3.Construction of DOX mouse,rat and human PBPK models and model analysisThe DOX mouse PBPK model was established by collecting DOX related physical and chemical parameters,physiological parameters and pharmacokinetic parameters,and predicted the plasma and tissue distribution of DOX in mice.The results were compared with the experimental data collected by the experimental and literature collection to explore the accuracy of the established model.The rat related parameters were used to replace the physiological parameters of mice,and the established mouse PBPK model was extrapolated to the rat,and the PBPK model was established to predict the pharmacokinetic behavior and tissue distribution of DOX.Two doses of DOX?5 mg/kg and 6 mg/kg?pharmacokinetic data were used from different literature sources to validate the model.The established mouse PBPK model species were extrapolated to the human,and the human PBPK model was established.DOX human plasma concentration data were used at three doses?25 mg/m²,40 mg/m²and 50 mg/m²?,further verified the reliability of the human PBPK model.Finally,the PBPK model was used to predict the plasma drug time curve of DOX in humans in the combination of DOX and PTX?discription order:DOX?PTX and PTX?DOX?.Then fitted with the measured data after the intravenous infusion reported in the literature to analyze the effects of PTX on the pharmacokinetic behavior of DOX in vivo.Based on the successfully established model,the sensitivity analysis of the CL was carried out to investigate the change of CL value,and compared the model simulation results with the measured data to investigate the effect of PTX on the pharmacokinetic behavior of DOX.Results:1.Establish UPLC-MS/MS method for detecting DOX and DOXol concentrations in miceThe DOX and DOXoL in mouse plasma and tissues showed a good linear relationship?r>0.99?.The RSD values of intra-and inter-day precision were<6.99%.The accuracy RE were±6.2%.The extraction recovery rate were 93.13%¹07.45%.The matrix effect was between 85%¹15%.The detection method was stable and reliable.2.Effect of PTX on pharmacokinetics and tissue distribution of DOX and DOXol in miceThe t-test of DOX and DOXol pharmacokinetic data showed that there was a statistically significant difference in t_1/2 and V_d value of DOX in the PTX?DOX group?P<0.05?,indicating that PTX may have an effect on the distribution of DOX in mice.However,there were no significant differences in the pharmacokinetic parameters of DOXol?P>0.05?,indicating that PTX had no effect on DOXol.By t-testing the heart concentration of DOX and DOXol in the co-administered group,there was no significant difference in the concentration of DOX and DOXol in the two groups?P>0.05?,indicating that PTX had no significant effect on the tissue distribution of DOX and DOXol in the heart.3.Construction of DOX mouse,rat and human PBPK models and model analysisThe DOX mouse PBPK model constructed in this paper could predict the pharmacokinetics and tissue distribution behavior of DOX mice well,indicating that the model fits well.The established mouse PBPK model was extrapolated to the rat and human by species,and the PBPK model of DOX was established respectively.The predicted and measured values of different doses were consistent,indicating that the constructed PBPK model could predict the pharmacokinetic behavior of DOX well in rats and human.Compared the DOX plasma concentration predicted by the PBPK model with the measured values,it was found that the model fit well when the infusion order was DOX?PTX,indicating that PTX had no effect on DOX pharmacokinetic behavior.For the PTX?DOX group,the plasma concentration of DOX increased before 48 h.The original PBPK model had large prediction error,and could not simulate the drug time curve of DOX in vivo.When the CL value was about 1/8 of the original value,the predicted value of the first 48 h concentration has a good approximation to the measured value.The closer to the original value for the CL value,the worse the prediction was.After 48 h,when the CL value was about 3/4¹ times of the original model value,the model prediction value and the measured value had a good fit.By analyzing the sensitivity of CL,the results indicated that the infusion of PTX first had an effect on the pharmacokinetics of DOX.Conclusions:The UPLC-MS/MS method established in the experiment has strong specificity and high sensitivity,and can be used for DOX and DOXol pharmacokinetic studies.The experimental results showed that PTX had an effect on the distribution of DOX mice,and had no significant effect on the cardiac distribution of DOX and DOXol.The establishment of DOX mouse PBPK model,as well as the PBPK model extrapolated to the rat and human body,can predict the pharmacokinetic behavior and tissue distribution of DOX in mice,rats and humans.In the combined chemotherapy,PTX has different effects on the pharmacokinetics of DOX with different administration sequence.When PTX is administered after infusion of DOX,PTX has no effect on DOX pharmacokinetics,but when PTX is administered as an infusion,PTX affects the pharmacokinetic behavior of DOX.