Chinese Liver Transplant Recipients Research Articles

The Population Pharmacokinetic Models of Tacrolimus in Chinese Adult Liver Transplantation Patients.

Aim. The aim of this study was to establish population pharmacokinetic models of tacrolimus in Chinese adult liver transplantation patients. Methods. Tacrolimus dose and concentration data (n = 435) were obtained from 47 Chinese adult liver transplant recipients, and the data were analyzed using a nonlinear mixed-effect modeling (NONMEM) method. Results. The structural model was a two-compartment model with first-order absorption. The typical population values of tacrolimus for the pharmacokinetic parameters of apparent clearance (CL/F), apparent distribution volume of the central compartment (V 2/F), intercompartmental clearance (Q/F), apparent distribution volume of the peripheral compartment (V 3/F), and absorption rate (k a) were 11.2 L/h, 406 L, 57.3 L/h, 503 L, and 0.723 h−1, respectively. The interindividual variabilities of these parameters were 16.2%, 163%, 19.7%, 199%, and 74.3%, respectively, and the intraindividual variability of observed concentration was 26.54%. The covariates retained in the final models were postoperative days (POD) and dosage per day (DOSE) on CL/F. Conclusion. Population pharmacokinetic models of tacrolimus were developed in Chinese adult liver transplant patients. These results could provide the interpretation of the outcome of pharmacokinetics modeling and the impact of covariate tested on individualized tacrolimus therapy.

Association of donor cytochrome P450 3A family polypeptide 5 and interleulin-18 polymorphisms with the individual dosage regimen of tacrolimns in chinese liver transplantation recipients

Objective To investigate the effect of cytochrome P450 3A family polypeptide 5 (CYP3A5) and interleukin-18 (IL-18) polymorphisms on the concentration/dose ratio of tacrolimus in Chinese liver transplant patients.Methods Donor CYP3A5 polymorphisms at rs776746 and IL-18 polymorphisms at rs5744247 were assessed by polymerase chain reaction (PCR) amplification and DNA sequencing for 84 liver transplant patients.The relationship between gene polymorphism and tacrolimus concentration/dose ralio was analyzed.Results The tacrolimus C/D ratios(ng.ml-1 ·mg-1 · kg-1) of the recipients with donors who were IL-18 rs5744247 GG + GC (163.1 ± 100.8) genotype were higher than those with donors who were CC genotype (116.7 ± 78.2,P ＜ 0.001).The tacrolimus C/D ratios of the recipients with donors who were CYP3A5 expressors and had IL-18 rs5744247 GG + GC genotype (133.4 ± 65.3) were higher than those with donors who were CYP3A5 expressors and had IL-18 rs5744247 CC genotype (88.3 ± 39.9,P ＜ 0.05).Conclusion Determination of donor CYP3A5 and IL-18 genotype may be performed prospectively to help individualizing tacrolimus dose regimen for liver transplant patients. Key words: Liver transplantation; Tacrolimus; Cytochrome P450 3A family polypeptide 5; Interleukin-18 ; Polymorphism

Establishment of High-Performance Liquid Chromatography and Enzyme Multiplied Immunoassay Technology Methods for Determination of Free Mycophenolic Acid and Its Application in Chinese Liver Transplant Recipients

Establishment of High-Performance Liquid Chromatography and Enzyme Multiplied Immunoassay Technology Methods for Determination of Free Mycophenolic Acid and Its Application in Chinese Liver Transplant Recipients

Association of MDR1 Gene SNPs and Haplotypes with the Tacrolimus Dose Requirements in Han Chinese Liver Transplant Recipients

BackgroundThis work seeks to evaluate the association between the C/D ratios (plasma concentration of tacrolimus divided by daily dose of tacrolimus per body weight) of tacrolimus and the haplotypes of MDR1 gene combined by C1236T (rs1128503), G2677A/T (rs2032582) and C3435T (rs1045642), and to further determine the functional significance of haplotypes in the clinical pharmacokinetics of oral tacrolimus in Han Chinese liver transplant recipients.Methodology/Principal FindingsThe tacrolimus blood concentrations were continuously recorded for one month after initial administration, and the peripheral blood DNA from a total of 62 liver transplant recipients was extracted. Genotyping of C1236T, G2677A/T and C3435T was performed, and SNP frequency, Hardy-Weinberg equilibrium, linkage disequilibrium, haplotypes analysis and multiple testing were achieved by software PLINK. C/D ratios of different SNP groups or haplotype groups were compared, with a p value<0.05 considered statistically significant. Linkage studies revealed that C1236T, G2677A/T and C3435T are genetically associated with each other. Patients carrying T-T haplotype combined by C1236T and G2677A/T, and an additional T/T homozygote at either position would require higher dose of tacrolimus. Tacrolimus C/D ratios of liver transplant recipients varied significantly among different haplotype groups of MDR1 gene.ConclusionsOur studies suggest that the genetic polymorphism could be used as a valuable molecular marker for the prediction of tacrolimus C/D ratios of liver transplant recipients.

The associations of IL-18 serum levels and promoter polymorphism with tacrolimus pharmacokinetics and hepatic allograft dysfunction in Chinese liver transplantation recipients

Interleukin 18 (IL-18) is a potent proinflammatory cytokine, which promotes the secretions of TNF-α, IL-1β, IL-2 and IFN-γ. All those inflammatory cytokines can influence the CYP450 and MDR dependent drug disposition. On the other side, those cytokines can induce hepatic allograft dysfunction. We investigated the effects of serum IL-18 and IL-18 gene promoter polymorphisms on tacrolimus pharmacokinetics and hepatic allograft dysfunction in liver transplant recipients. A total of 155 liver transplant recipients were enrolled into this study (34 females and 121 males). The mean follow-up was 52 months (range 16–96 months).The total liver transplant recipients were divided into hepatic allograft dysfunction (N = 14) and no hepatic allograft dysfunction (N = 141). We studied two single-nucleotide polymorphisms in the promoter region of IL-18 gene at the position G-137C (rs187238) and A-607C (rs1946518) by HRM analysis (high-resolution melting curve analysis). Tacrolimus dosage, tacrolimus blood concentration, serum levels of IL-18 and IFN-γ were also investigated. We found the recipients with higher IL-18 and IFN-γ serum levels had lower tacrolimus concentration/dose (C/D) ratios (P < 0.05). In the mean time, after transplantation hepatic allograft dysfunction was more likely to happen to those recipients. However, there was no significant difference in the frequencies of A-607C and G-137C allelic distribution in recipients' tacrolimus concentration/dose (C/D) ratios. This study identifies IL-18 reduced tacrolimus concentration/dose (C/D) ratio through up regulation of P-glycoprotein (P-gp).

Pharmacokinetics of tacrolimus converted from twice-daily formulation to once-daily formulation in Chinese stable liver transplant recipients

To evaluate the pharmacokinetics of tacrolimus in Chinese stable liver transplant recipients converted from immediate release (IR) tacrolimus-based immunosuppression to modified release (MR) tacrolimus-based immunosuppression. Open-label, multi-center study with a one-way conversion design was conducted. Eighty-three stable liver recipients (6-24 months post-transplant) with normal renal and stable hepatic function were converted from IR tacrolimus twice-daily treatment to MR tacrolimus once-daily treatment on a 1:1 (mg: mg) total daily dose basis. Twenty-four hour pharmacokinetic studies were carried out on d 0 (pre-conversion), d 1, and d 84 (post-conversion). The area under the blood concentration-time curve of MR tacrolimus from 0 to 24 h (AUC(0-24)) on d 1 was comparable to that of IR tacrolimus on d 0, with a 90% confidence interval (CI) for MR/IR tacrolimus of 92%-97%. The AUC(0-24) value for MR tacrolimus on d 84 with the daily dose increased by 14% was approximately 17% lower than that for IR tacrolimus. The 90% CI was 77%-90%, outside the bioequivalence range of 80%-125%. There was a good correlation between AUC(0-24) and concentration at 24 h (C(24)) for IR tacrolimus (d 0, r=0.930) and MR tacrolimus (d 1, r=0.936; d 84, r=0.903). The exposure to tacrolimus when administered MR tacrolimus once daily is not equivalent to that for IR tacrolimus twice daily after an 84-day conversion in Chinese stable liver transplant recipients. The dose should be adjusted on the basis of trough levels. The therapeutic drug monitoring for patients treated with IR tacrolimus is considered to be applicable to MR tacrolimus.

Cylex ImmuKnow assay in Chinese stable liver transplant recipients

Objective To identify the level of functional immunity as measured by the ImmuKnow assay in Chinese stable liver transplant recipients and to correlate these values with the dose and the trough levels of immunosuppressant, and with other clinical parameters of these patients. Methods Functional immune response was assessed by the ImmuKnow assay in 46 blood samples taken from 46 stable liver transplant recipients from Beijing Youan Hospital, Capital Medical University Liver Transplantation Center. Results The average ATP value in these stable liver transplant recipients was 203±114 ng/ml (range: 38.47 ATP ng/ml to 524.06 ATP ng/ml) at 22± 15 month post liver transplantation. There was no correlation either between ImmuKnow ATP values and the tacrolimus trough levels, or between ImmuKnow ATP values and the liver function (P<0. 05). Stepwise multiple regression analysis identified WBC and CD3+, CD3+ CD4+ as independent predictors of ImmuKnow assay levels when age, gender and underlying diagnosis were taken into account (P<0. 05). Five patients who were detected to have active HCV infection had lower ImmuKnow ATP values (<61 ng/ml). Conclusions The Cylex ImmuKnow assay ATP values were lower in Chinese stable liver transplant recipients compared with American patients. Further investigation is required to determine the role of the ImmuKnow assay in tailoring immunosuppressant therapy in liver transplant recipients. Key words: Liver transplant; The ImmuKnow assay; Immunosuppression

Population Pharmacokinetic Study of Cyclosporine Based on NONMEM in Chinese Liver Transplant Recipients

A population pharmacokinetic study of cyclosporine (CsA) was performed in liver transplant recipients. A total of 3731 retrospective drug monitoring data points at predose (C0) and 2 hours postdose (C2) were collected from 124 liver transplant recipients receiving CsA microemulsion. Population pharmacokinetic analysis was performed using the program NONMEM (nonlinear mixed-effect modeling). Various covariates potentially related to CsA pharmacokinetics were explored, and the final model was validated by a bootstrap method and by assessing the predictive performance using empiric Bayesian estimates. A one-compartment model with first-order absorption was considered. Population parameters of apparent clearance (CL/F) and volume of distribution were estimated as 23.1 L/h and 105 L, respectively. CL/F was influenced by four covariates: duration of CsA therapy (DT), hematocrit (HCT), and concurrent prednisone dose (PR). The final model for CL/F was fitted as follows: CL/F = 23.1 + 0.5 × (DT/200) - 0.07 × HCT + 0.04 × PR. The interindividual variability in CL/F, volume of distribution, and Ka calculated as coefficient of variation were 15.1%, 9.3%, and 66.0%, respectively. The intraindividual variability was 18.6%. The model fitted well with the observed data, and the bootstrap method guaranteed robustness of the population pharmacokinetic study model. Model validation was performed by a visual predictive check. Moreover, simulation was conducted to facilitate the individualized treatment based on patient information and the final model. The model to characterize population pharmacokinetic study of CsA provided better clinical individualization of CsA dosing in liver transplant recipients based on patient information and to assess patients' suitability for CsA therapy.

Establishment of High-Performance Liquid Chromatography and Enzyme Multiplied Immunoassay Technology Methods for Determination of Free Mycophenolic Acid and Its Application in Chinese Liver Transplant Recipients

The objective of this study is to investigate the correlation between methods of high-performance liquid chromatography (HPLC) and enzyme multiplied immunoassay technology (EMIT) for determination of total mycophenolic acid (tMPA) and free (fMPA) concentration and to study pharmacokinetics of fMPA in Chinese liver transplant recipients. An HPLC method with fluorometric detection and an EMIT assay were established to determine fMPA in plasma ultrafiltrates. Pharmacokinetic parameters of tMPA and fMPA in 51 patients were estimated. The calibration range of fMPA was 0.0025 to 1.0 μg/mL for the HPLC method and 0.0050 to 0.50 μg/mL for the EMIT method. Mean recovery of the two methods was 98.0% and 97.1%, respectively. The intraday and interday coefficient of variations were 0.93% to 3.1% and 1.6% to 2.9% for HPLC and 4.51% to 15.8% and 5.83% to 19.5% for EMIT, respectively. The relationship of the two methods was EMIT = 1.074 × HPLC + 0.582 (r2 = 0.918, n = 470, P < 0.05) for tMPA and EMIT = 1.068 × HPLC + 0.004 (r2 = 0.945, n = 297, P < 0.05) for fMPA. There was a positive mean bias of EMIT for tMPA (27.0%) and fMPA (23.3%). The AUC0-12 of tMPA and fMPA obtained by HPLC in 51 patients was 34.7 ± 11.1 and 0.72 ± 0.38 μg·h/mL, respectively. The free fraction of MPA was 1.60 ± 1.21% (Median:1.36%, interquartile: 0.72, 2.22), [corrected] which was significantly correlated with 7-O-glucuronide conjugate of MPA AUC0-12 (r2 = 0.705, P < 0.001), albumin (r2 = -0.529, P < 0.001), and the clearance of creatinine (r2 = -0.417, r2 = 0.005). Both HPLC and EMIT assay are suitable for the determination of fMPA. A considerable interindividual variability exists in pharmacokinetics of fMPA among Chinese liver transplant recipients. 7-O-Glucuronide conjugate of MPA and albumin concentrations are two factors correlated to fMPA variance.

Immune Cell Functional Assay in Monitoring of Adult Liver Transplantation Recipients With Infection

To identify the levels of functional immunity measured by the ImmuKnow assay in Chinese liver transplantation recipients and its application in monitoring the risk of posttransplant infection. Forty-five apparent healthy Chinese and 106 adult liver transplant (LT) recipients were under investigation. LTs were grouped in stable status or infection according to their clinical diagnosis. Whole blood samples were collected freshly and cultured within 6 hr, the CD4(+) T cells were selected, and their adenosine triphosphate (ATP) value was assayed the next day. Before stimulation, we also examined the percentage of T-helper (Th; CD3(+) CD4(+)) and T-suppress (Ts; CD3(+) CD8(+)) lymphocyte subpopulations and the ratio of Th/Ts. The average ImmuKnow assay in infectious LT recipients was 128 + or - 84 ng/mL, significantly lower (P<0.05) than that in stable LTs (305 + or - 149 ng/mL) or in normal adults (301+ or - 101 ng/mL). The ImmuKnow values in LTs had a good negative correlation to infection clinically (r = -0.6217, P<0.001). Infectious risk was high when the ImmuKnow value was less than 130 ng/mL (odds ratio=13, 95% confidence interval 6.0-29.4, P<0.01). The sensitivity of low ImmuKnow values in posttransplant infection was 85.2%, significantly higher than those of Th/Ts ratio and immunosuppressant trough levels (P<0.01); specificity was 76.3%, comparable with that of Th/Ts ratio (75.5%), but greatly higher than immunosuppressant trough levels (P<0.01). ImmuKnow ATP values had no correlation with Th/Ts ratio or immunosuppressant trough levels. ImmuKnow ATP levels are lower in LT recipients with infection, which provides a new tool in monitoring posttransplant infection, and an index of tailoring immunosuppression clinically.

Follow-up of Chinese liver transplant recipients in Hong Kong

The outcome of liver transplantation in China remains speculative. From 1998 to 2007, 177 adult Hong Kong patients underwent liver transplantation in China and were subsequently followed up at Queen Mary Hospital, Hong Kong. One hundred six (59.9%) patients had hepatocellular carcinoma (HCC). The grafts were probably derived from uncontrolled non-heart-beating donors. The 1-month mortality rate was 4.0%. The 1-, 3-, and 5-year overall survival rates were 73.9%, 59.0%, and 53.9%, respectively. The 5-year overall survival rates for non-HCC, HCC, HCC (within the Milan criteria), and HCC (beyond the Milan criteria) patients were 66.3%, 44%, 58%, and 26.2%, respectively. The long-term survival was compromised by the high incidence of HCC recurrence and graft failure secondary to diffuse intrahepatic biliary strictures. The overall survival rate of the entire group was lower than that of the patients receiving deceased donor liver grafts at Queen Mary Hospital in the same period. For non-HCC patients, however, the 5-year survival rate of 66.3% was comparable to that of recent reports from the Western world.

Models for the prediction of mycophenolic acid area under the curve using a limited-sampling strategy and an enzyme multiplied immunoassay technique in chinese patients undergoing liver transplantation

Background: An enzyme multiplied immunoassay technique (EMIT) provides convenient and accurate measurements of mycophenolic acid (MPA) concentrations for determination of immunosuppression during treatment with mycophenolate mofetil (MMF). No abbreviated model for estimating the full 12-hour MPA AUC using an EMIT assay in liver transplant recipients has been described previously. Objective: This study was conducted to determine the best model for predicting the MPA AUC using the EMIT method and a limited-sampling strategy in Chinese patients undergoing liver transplantation. Methods: The study enrolled consecutive liver transplant patients who were receiving MMF 1 g BID along with tacrolimus. A complete MPA pharmacokinetic profile was obtained for each patient on a single day, 7 to 14 days after transplantation. The EMIT method was used to determine MPA concentrations before dosing and at 0.5, 1, 1.5, 2, 4, 6, 8, 10, and 12 hours after dosing on the sampling day. Multiple linear regression analysis was used to evaluate potential models for estimating the full 12-hour MPA AUC. The accuracy and robustness of the models were evaluated using bootstrap analysis. Prediction error and prediction bias were calculated. Agreement between the estimated MPA AUC 0-12 and the full 12-hour MPA AUC was investigated using Bland-Altman analysis. Results: The study enrolled 48 Chinese liver transplant recipients (45 male, 3 female) with a mean (SD) age of 50 (12) years, mean weight of 64 (12) kg, and mean height of 169 (6) cm. Twenty-four models that included blood sampling at 1 through 4 time points were developed ( r 2 = 0.015–0.950). Four models with the highest r 2 values were selected; the lack of significant differences from the original dataset on bootstrap analysis indicated acceptable accuracy and robustness. The best model for predicting the MPA AUC 0-12 employed concentrations at 1, 2, 4, and 8 hours; 40 of 48 (83.3%) MPA AUC 0-12 values estimated using this model were within 15% of the full 12-hour MPA AUC. This model had a minimal mean prediction error (mean [SD], 0.27% [1.79%]) and mean absolute prediction error (8.83% [1.24%]). On Bland-Altman analysis, this model also had the best agreement between the estimated MAP AUC 0-12 and the full 12-hour MPA AUC, with a mean error of 9.02 mg · h/L. Conclusions: In this small group of Chinese liver transplant patients receiving MMF and concomitant tacrolimus, models for estimating the MPA AUC 0-12 were developed using the EMIT method and a limited-sampling strategy. The best model for prediction of the full 12-hour MPA AUC was 4.46 + 0.81 · C1 + 1.78 · C 2+2.51·C 4+4.94·C8.

Monitoring mycophenolic acid pharmacokinetic parameters in liver transplant recipients: Prediction of occurrence of leukopenia

Mycophenolate mofetil (MMF) is a very powerful immunosuppressive drug used in preventing acute rejection in liver transplantation. However, MMF has some serious side effects, including hematologic and gastrointestinal disorders. This study was designed to investigate the relationship between the clinical events and the pharmacokinetics of mycophenolic acid (MPA) in Chinese liver transplant recipients. Sixty-three adult liver transplant recipients receiving 1.0 g of MMF twice daily in combination with tacrolimus were prospectively included. The MPA pharmacokinetic profiles (blood sampling time points: before the dose and 0.5, 1, 1.5, 2, 4, 6, 8, 10, and 12 hours after the dose) were monitored after transplantation. Every clinical event, including acute and MMF-related side effects, was monitored in all patients within 3 months. Two patients (3.2%) had an episode of acute rejection. Forty-two patients (66.7%) had 52 episodes of MMF-related side effects, including leukopenia, diarrhea, and infection. The 0-hour concentration (C(0h)), maximum (peak) concentration (C(max)), and area under the curve from 0 to 12 hours (AUC(0-12h)) in patients with side effects were significantly higher than those in patients without side effects (P < 0.05). The thresholds of side effects from receiver operating characteristic analysis were 2 mg/L (sensitivity, 52.4%; specificity, 90.5%) for C(0h), 10 mg/L (sensitivity, 45.2%; specificity, 85.7%) for C(max), and 40 mg h/L (sensitivity, 71.4%; specificity, 61.9%) for AUC(0-12h) (P < 0.05). Leukopenia was discriminated effectively in C(0h) and in C(max) (P < 0.05). These results demonstrate the close relationship between leukopenia and MPA pharmacokinetic parameters in the early period after liver transplantation. C(0h) and AUC(0-12h) of MPA could predict the subsequent occurrence of leukopenia. These values may be used in routine monitoring for MMF therapy.

Polymorphisms in Cytokine Genes and Their Association with Acute Rejection and Recurrence of Hepatitis B in Chinese Liver Transplant Recipients

Acute rejection (AR) and hepatitis B virus (HBV) recurrence after liver transplantation (LT) are the two major complications leading to chronic graft dysfunction. Genomic polymorphisms in interleukin (IL)-10, tumor necrosis factor (TNF)alpha and transforming growth factor (TGF)beta1 genes have been found to affect the susceptibility to certain diseases. However, the relationship between cytokine gene polymorphisms and risk of AR as well as HBV recurrence after LT in Han Chinese has not been reported. The objective of the present study was to investigate the association of polymorphisms within these cytokine genes with the risk of AR as well as HBV recurrence. One hundred eighty six Chinese LT recipients in which 41 patients developed AR and 29 patients experienced HBV recurrence were enrolled; 151 age- and gender-matched healthy individuals were selected as controls. Single-nucleotide polymorphisms (SNPs) at loci of IL-10 -1082, -819, -592, and TNFalpha -308, -238, as well as TGFbeta1 -988, -800, -509, +869, and +915 were determined by using DNA sequencing and then confirmed by restriction fragment length polymorphism (PCR-RFLP). Analyses of linkage disequilibrium and haplotype frequency were performed using Haploview program. The -819 and -592 polymorphisms in the IL-10 gene were in complete linkage (r(2) = 1). Another linkage was found at -509 and +869 in the TGFbeta1 gene (r(2) = 0.66). A significant difference was observed in the distribution of allelic frequencies at position -819 and -592 in the IL-10 gene between ARs and non-ARs (p = 0.036, OR = 1.134, 95% CI 0.999-1.287 and p = 0.036, OR = 1.134, 95% CI 0.999-1.287, respectively). After adjustment for a Bonferroni correction, there was no significant difference between the polymorphism and AR (p >0.05). Furthermore, the overall genotype distribution between HBV recurrence patients and non-HBV recurrence patients was also not significantly different (p >0.05). Our study suggests that gene polymorphisms of IL10, TNFalpha, and TGFbeta1 do not have a major independent role in AR and HBV recurrence after LT and may not be risk factors of AR and HBV recurrence after LT in Chinese liver transplant recipients.

Pharmacokinetics of Mycophenolic Acid and Determination of Area Under the Curve by Abbreviated Sampling Strategy in Chinese Liver Transplant Recipients

This study aimed to: (i) define the clinical pharmacokinetics of mycophenolic acid (MPA) in Chinese liver transplant recipients; and (ii) develop a regression model best fitted for the prediction of MPA area under the plasma concentration-time curve from 0 to 12 hours (AUC(12)) by abbreviated sampling strategy. Forty liver transplant patients received mycophenolate mofetil 1g as a single dose twice daily in combination with tacrolimus. MPA concentrations were determined by high-performance liquid chromatography before dose (C(0)) and at 0.5 (C(0.5)), 1 (C(1)), 1.5 (C(1.5)), 2 (C(2)), 4 (C(4)), 6 (C(6)), 8 (C(8)), 10 (C(10)) and 12 (C(12)) hours after administration on days 7 and 14. A total of 72 pharmacokinetic profiles were obtained. MPA AUC(12) was calculated with 3P97 software. The trough concentrations (C(0)) of tacrolimus and hepatic function were also measured simultaneously. Multiple linear regression analysis was used to establish the models for estimated MPA AUC(12). The agreement between predicted MPA AUC(12) and observed MPA AUC(12) was investigated by Bland-Altman analysis. The pattern of MPA concentrations during the 12-hour interval on day 7 was very similar to that on day 14. In the total of 72 profiles, the mean maximum plasma concentration (C(max)) and time to reach C(max) (t(max)) were 9.79 +/- 5.26 mg/L and 1.43 +/- 0.78 hours, respectively. The mean MPA AUC(12) was 46.50 +/- 17.42 mg . h/L (range 17.99-98.73 mg . h/L). Correlation between MPA C(0) and MPA AUC(12) was poor (r(2) = 0.300, p = 0.0001). The best model for prediction of MPA AUC(12) was by using 1, 2, 6 and 8 hour timepoint MPA concentrations (r(2) = 0.921, p = 0.0001). The regression equation for estimated MPA AUC(12) was 5.503 + 0.919 . C(1) + 1.871 . C(2) + 3.176 . C(6) + 3.664 . C(8). This model had minimal mean prediction error (1.24 +/- 11.19%) and minimal mean absolute prediction error (8.24 +/- 7.61%). Sixty-three of 72 (88%) estimated MPA AUC(12) were within 15% of MPA AUC(12). Bland-Altman analysis also revealed the best agreement of this model compared with the others and a mean error of +/-9.89 mg . h/mL. This study showed the wide variability in MPA AUC(12) in Chinese liver transplant recipients. Single timepoint MPA concentration during the 12-hour dosing interval cannot reflect MPA AUC(12). MPA AUC(12) could be predicted accurately using 1, 2, 6 and 8 hour timepoint MPA concentrations by abbreviated sampling strategy.

Validation of limited sampling strategy for the estimation of mycophenolic acid exposure in Chinese adult liver transplant recipients

Mycophenolate mofetil (MMF) is indicated as immunosuppressive therapy in liver transplantation. The abbreviated models for the estimation of mycophenolic acid (MPA) area under the concentration-time curve (AUC) have been established by limited sampling strategies (LSSs) in adult liver transplant recipients. In the current study, the performance of the abbreviated models to predict MPA exposure was validated in an independent group of patients. A total of 30 MPA pharmacokinetic profiles from 30 liver transplant recipients receiving MMF in combination with tacrolimus were used to compare 8 models' performance with a full 10 time-point MPA-AUC. Linear regression analysis and Bland-Altman analysis were used to compare the estimated MPA-AUC0-12h from each model against the measured MPA-AUC0-12h. A wide range of agreement was shown when estimated MPA-AUC0-12h was compared with measured MPA-AUC0-12h, and the range of coefficient of determination (r2) was from 0.479 to 0.936. The model based on MPA pharmacokinetic parameters C1h, C2h, C6h, and C8h had the best ability to predict measured MPA-AUC0-12h, with the best coefficient of determination (r2=0.936), the excellent prediction bias (2.18%), the best prediction precision (5.11%), and the best prediction variation (2SD=+/-7.88 mg.h/L). However, the model based on MPA pharmacokinetic sampling time points C1h, C2h, and C4h was more suitable when concerned with clinical convenience, which had shorter sampling interval, an excellent coefficient of determination (r2=0.795), an excellent prediction bias (3.48%), an acceptable prediction precision (14.37%), and a good prediction variation (2SD=+/-13.23 mg.h/L). Measured MPA-AUC0-12h could be best predicted by using MPA pharmacokinetic parameters C1h, C2h, C6h, and C8h. The model based on MPA pharmacokinetic parameters C1h, C2h, and C4h was more feasible in clinical application.

Tacrolimus dose requirement in relation to donor and recipientABCB1 andCYP3A5 gene polymorphisms in Chinese liver transplant patients

The aim of this study was to investigate whether the heterogeneity in tacrolimus dose requirement is associated with ABCB1 and CYP3A5 gene polymorphisms in Chinese liver transplant patients during the first month after transplantation. ABCB1 and CYP3A5 genotyping was performed using the polymerase chain reaction restriction sites polymorphism-based procedure in Chinese liver transplant recipients (n = 50) and their corresponding donors (n = 50). Tacrolimus whole-blood trough concentrations were measured by immunoassays on the IMx analyzers (Abbott Diagnostics Laboratories, Abbott-Park, IL). Doses required to achieve target blood concentrations and dose-adjusted trough concentrations (concentration/dose [C/D] ratios) were compared among patients according to allelic status of ABCB1 and CYP3A5. The ABCB1 3435CC was observed in 23 subjects (23%), whereas 64 (64%) carried 3435CT and 13 (13%) carried 3435TT. The CYP3A5*1/*1 was observed in 13 subjects (13%), 50 (50%) carried *1/*3, and 37 (37%) carried*3/*3. The tacrolimus C/D ratios were obviously lower in recipients carrying ABCB1 3435CC genotype. For CYP3A5, recipients who received organs from CYP3A5*3/*3 donors had higher C/D ratios. But the donors' ABCB1 and recipients' CYP3A5 genotype did not affect the recipients' pharmacokinetics. Analysis of the combination of recipients' ABCB1 and donors' CYP3A5 genotypes revealed that the tacrolimus C/D ratios were significantly lower in the ABCB1 3435CC-carrying recipients, regardless of donors' CYP3A5 genotype. In conclusion, our finding suggests that the recipients' ABCB1 and donors' CYP3A5 genotype affect the tacrolimus dose requirements. ABCB1 C3435T polymorphism is a major determinant of tacrolimus trough concentration in Chinese liver transplant recipients, and recipients with 3435CC genotype will require higher dose of tacrolimus.

Cyclosporine microemulsion C2 monitoring in Chinese adult liver transplant recipients: a preliminary randomized control trial

To evaluate the safety and reliability of cyclosporine microemulsion (CsA-ME) C(2) monitoring and to determine the target level of C(2) in Chinese adult liver transplant recipients. 53 Chinese adult liver transplant recipients were randomly divided into three groups (group C(0), n = 17; group high level C(2), n = 18; group low level C(2), n = 18). Blood chemistry reflecting heart, liver and renal function and CsA level were examined at certain interval during follow-up. The change of immune status and episodes of rejection were also observed closely. The group low level C(2) had the lowest CsA oral dose (2.51 +/- 0.37 mg/kg/d), and had significant difference compared with the other groups (P < 0.01). The best liver, heart and renal function was observed in group low level C(2). The CD(4)(+)/CD(8)(+) ratio of group low level C(2) was 1.04 +/- 0.68, which had no significant difference with C(0) group. The rejection incidence of the three groups had no significant difference. group low level C(2) had highest clinical benefit ratio (72.22%), while the clinical benefit of group high level C(2) is the lowest (11.11%). With rational target level, C(2) monitoring can show us the proper oral dose of CsA which can decrease the side effects remarkably without rejection episodes increasing. The target level of C(2) in Chinese adult liver transplant recipients might be: 600-800 ng/ml 1 to 6 months posttransplant, 400-600 ng/ml 7-12 months posttransplant.

Analysis of variability of drug exposure and blood concentration during Neoral absorption phase in Chinese adult liver transplant recipients

目的 通过分析中国成人肝移植受体中Neoral吸收期血药浓度与药物暴露量的变异性,为临床上发展新的Neoral治疗药物监测方法提供理论依据.方法通过定期测定22例中国成人肝移植受体口服Neoral前及服药后1、2、3、4 h的血药浓度,采用个体及群体药代动力学的方法计算出个体内和个体间变异系数(CV).结果 Neoral血药浓度和AUC0～4的个体内和个体间变异系数均在服药头2 h达到高峰,此后逐渐下降.术后10～11 d个体间的浓度及AUC变异系数均最高.结论 Neoral吸收期的变异性主要集中在服药后头2 h.服药后1 w左右是变异性最大的时期。