Monitoring Tigecycline Plasma Concentration And Application To Population Pharmacokinetic/Pharmacodynamic Study In Patients

Objective:To develop a LC-MS/MS method for the monitoring of tigecycline concentration in patients with infection.The factors that affect the pharmacokinetic characteristics of tigecycline were analyzed base on tigecycline concentration data,patient demographic information and laboratory examination.a population pharmacokinetic model of tigecycline in infected patients was established,combined with susceptibility results(MIC),we established a population pharmacokinetic/pharmacodynamic model for provide reference for individualized treatment of tigecycline.Methods:Establishment of determination of tigecycline plasma concentration in patients.Plasma samples were precipitated by methanol with tigecycline-d9 as internal standard,The mobile phase was methanol:water(containing 0.1%formic acid v/v),the gradient elution was performed.A tandem mass spectrometer equipped with electrospray ionization source was used as detector and operated in positive ion mode.and method validation was carried out according to guidelines for validation of quantitative analysis of biological samples.Determination MIC of tigecycline agaist acinetobacter baumannii.Determining MIC of acinetobacter baumannii by broth microdilution method,agar dilution method and disk diffusion method,and comparing the result of three method.Establishment of PPK/PD model of tigecycline in infected patients.67 patients with infection were enrolled from October 2018 to March 2019.Covariate of gender,age,weight,TBIL,ALT,AST,BUN,Cr,et al was analyzed whether it affect the pharmacokinetic characteristics or not.PPK/PD model was established and verified by NONMEN software base on tigecycline concentration in plasma of 67 patients.Results:The calibration curves were linear ranging from 50 to 2000 ng·mL-1(R2=0.997).The accuracy of lower limit of quantification(50 ng·mL-1)was between 96.48%and 105.42%and RSD(%)<3.475%.The RSD(%)was less than 8.19%for intra-day and less than 7.84%for inter-day respectively.The average recovery of tigecycline at low,medium and high QC were 98.44%,104.61%and 107.27%,respectively,with RSD(%)<7.67%.There was no endogenous interfering peaks in blank samples and carry over of tigecycline is 0.RSD(%)of matrix is less than 15%.The RE(%)and RSD(%)results of the samples placed in the sample injector for 24 h,left at room temperature for 2 h,frozen and thawed 3 times at-200 C.,and frozen at-200 C.for 1 month were less than 15%.A total of 134 strains of acinetobacter baumannii isolated from clinical departments were obtained.The susceptibility,intermediation and resistance rates were 65.67%,18.66%and 15.67%for broth microdilution method,5.97%,41.04%and 52.99%for agar dilution method,0.75%,13.43%and 85.82%for disk diffusion method,respectively.The MIC50=4μg·mL-1 and MIC90=8 μg mL-1 of tigecycline agaist acinetobacter baumannii by microbroth dilution method.The results of the covariate investigation showed that BUN within a certain range(1.8-48.3mmol/L)had a significant influence on the clearance rate.The larger the BUN value was,the smaller the clearance rate was CL=25.2*(BUN/9)^-0.271.The model was verified 1000 times using Bootstrap method and the success rate was 100%.The results of PPK/PD simulation showed that when the maintenance dose was 50mg,AUC/MIC50 was in the range of 0.8-1.4,and AUC/MIC90 was in the range of 0.4-0.7.When the maintenance dose was 100mg,AUC/MIC50 was in the range of 1.6-2.75,and the AUC/MIC90 was in the range of 0.8-1.4.Conclusion:The results of the covariate investigation showed that BUN within a certain range(1.8-48.3mmol/L)had a significant influence on the clearance rate.The larger the BUN value was,the smaller the clearance rate was.AUC/MIC and Cmax/MIC at different maintenance doses in ranger of BUN(1.8-48.3 mmol/L)was successfully simulated by using this model.When the maintenance dose was 50mg,ratio of AUC/MIC90 was below PK/PD break points(AUC0-24h/MIC>0.9),while the maintenance dose was 100mg,ratio of AUC/MIC90 was above PK/PD breakpoints.In this study,according to PK/PD of tigecycline,100mg tigecycline maintenance dose was better than 50mg.In this study,MIC of acinetobacter baumannii was determined by broth microdilution method,agar dilution method and disk diffusion method.The resistance rate of disk diffusion method(85.82%)and agar dilution method(52.99%)were much higher than that of microdilution method(15.67%).To obtain accurate MIC of acinetobacter baumannii,broth microdilution method should be adopted as far as possible.This method is accurate,quick and reliable for the determination of tigecycline in human plasma.Tigecycline-d9 was used as internal standard,it can reduce the effect of matrix effect.This method could be widely used for therapeutic drug monitoring(TDM)and pharmacokinetic study of tigecycline.