Therapeutic Drug Monitoring Of Mycophenolate Mofetil And The Influence Of Gene Polymorphism In Renal Transplant Recipients

OBJECTIVE To evaluate the role of drug trough concentration monitoring of mycophenolate mofetil(MMF)in renal transplantation patients.Then to assess the influence of the gene polymorphisms of drug-metabolizing enzymes and transporters on the pharmacokinetics of MMF,and to investigate the association between of gene polymorphisms and the gastrointestinal adverse effects of MMF.METHODS 1.We established the HPLC detection method of MPA,MPAG in human plasma and validated firstly.Drug concentrations of MPA and MPAG in 206 renal transplant recipients were grouped according to adverse drug reactions.We found the cut off value of f MPA,MPAG concentration by the ROC curve analysis.And then the AUC in 24 cases of early recipients of renal transplantation was determined,their pharmacokinetic parameters were analyzed by DAS software.To estimate the regression equation of MPAAUC0-12 h by stepwise regression method with SPSS software lastly.The Bland-Altman method was used to evaluate the accuracy of the method.2.To explore the effects of MMF on pharmacokinetics by SNPs,UGT,ABCC,ABCG,SLCO1 B and SLC22 A genotyping were performed using the Sequenom Mass Array system,24 renal transplant recipients were measured by AUC.And MMF related gastrointestinal adverse effects were recorded in 199 renal transplant recipients during follow-up,to investigate the association between gene polymorphism and MMF relatedgastrointestinal adverse effects by SPSS software and Haploview 4.2 genetic analysis software.RESULTS1.The assay was linear with in 0.2~50 μg /m L for MPA,2.5~500μg /m L for MPAG(r >0.999).Absolute recovery rates of MPA,MPAG were more than 80%,therecoveries were between 90%~110%.The intra-day and inter-day RSDs were both lower than 10%.2.In 2015.8 ~2016.12,the cases of the renal transplantation followed up was820.There were 55 cases of infection,34 cases of MMF related gastrointestinal reactions,and 322 cases of bone marrow toxicity.Based on the analysis of MPA and MPAG concentration in ROC curve,found that MPA C0 less than 2.36mg/L,MPAG C0 greater than 40.70mg/Lwas the best cut-off value of adverse drug reactions.3.Single point was badly correlated with detected AUC.Abbreviated MPA model equations based on 1,4,8 h three or 0.5,1,4,8h four sampling times were fitted to MPAAUC0-12 h.Therefore,recommend the regression model MPAAUC0-12h=4.74+4.65C4+1.656C1+4.538C8(r2=0.929)in view of predictive accuracy,detection cost and operability.4.Gene of UGT1A9 rs13418420、UGT1A8 rs1042597 and SLC22A8 rs4149180 polymorphism was significantly correlated with MMF related gastrointestinal adverse effects.There were differences in the distribution of the 3 genotypes of UGT1A9rs13418420、UGT1A8 rs1042597 and SLC22A8 rs4149180 in the normal group and the gastrointestinal reaction group.Their P values are 0.0277,0.0277,0.0062.5.The GGAAATC haplotype of UGT2B7 rs12233719-rs28365062-rs28365063-rs4292394-rs62298861-rs7438135-rs7439366,the frequency was 0.476 MMF gastrointestinal reaction group and higher thanin normal group 0.309 sgnificantly,p=0.028.6.To analyze the effects of different genotypes on the pharmacokinetic parameters of MPA and MPAG.The impact on MPAAUC0-12 h is ABCG2rs2231142(23.83±3.39vs30.40±10.51,p=0.034);The impact the value of MPAAUC0-12h/MPAGAUC0-12 h is SLCO1B1 rs4149057(.0443±.01481 vs.0710±.03440,p=0.022);The impact the value of MPACmax is SLCO1B1 rs2291075(5.75±1.81 vs 8.17±2.43,p=0.014)。CONCLUSION1.The method is accurate,convenient and rapid,which could be used in thequantitative determination of plasma concentration of MPA,MPAG in renal transplantion patients.2.Monitoring the trough concentration of MPA and MPAG can be used as indicators of MMF drug monitoring.MPA C0 is less than 2.36mg/L,MPAG C0 is greater than40.70mg/Lwas the best cut-off value of adverse drug reactions.3.The abbreviated model equations established in 1,4,8 h three sampling times could estimated the MPAAUC0-12 h in renal allograft recipients.And it is recommend for MPA therapeutic drug monitoring in Chinese renal allograft recipients treated with MMF.4.The ABCG2 rs2231142,SLCO1B1 rs4149057,SLCO1B1 rs2291075 variant is one of the determinant factors governing the renal allograft recipients variability in the pharmacokinetics of MMF.5.Gene of UGT1A9 rs13418420、UGT1A8 rs1042597 and SLC22A8 rs4149180 polymorphism was significantly correlated with MMF gastrointestinal reaction.The GGAAATC haplotype of UGT2B7rs12233719-rs28365062-rs28365063-rs4292394-rs62298861-rs7438135-rs7439366 is the risk factors for MMF related gastrointestinal reactions.