肝移植患者他克莫司血药浓度与细胞色素P450 3A5 1*3基因多态性的关系

目的研究细胞色素P450 3A5 1*3基因多态性对肝移植患者他克莫司(免疫抑制剂)血药浓度的影响,探讨他克莫司在不同个体间吸收、代谢差异的基因背景。方法观察150例肝移植术后常规使用他克莫司 吗替麦考酚酯胶囊 醋酸泼尼松三联免疫抑制治疗的成年患者,分别测定术后1、3、6个月和12月的他克莫司全血药浓度,采用等位基因特异PCR测定细胞色素P450 3A5 1*3基因多态性,比较不同基因型之间他克莫司的浓度/剂量比的差异。结果在口服相同剂量的他克莫司时,1个月内CYP3A5 1*1、CYP3A5 1*3和CYP3A5 3*3三种基因型的浓度/剂量比,差异不显著;但3个月后,差异显著;6个月和12个月的浓度/剂量比,差异非常显著。结论CYP3A5 1*3多态性与肝移植患者他克莫司血药浓度具有非常显著的相关性,携带等位基因1*1和1*3患者的血药浓度明显低于3*3纯合子患者。     

肾移植受者CYP3A5基因多态性对他可莫司代谢的影响

目的研究CYP3A基因多态性对肾移植受者他可莫司代谢的影响。方法50例肾移植受者采用FK506＋霉酚酸酯＋强的松三联免疫抑制方案,FK506起始剂量0．15mg／（kg·d）,1w后根据目标血药浓度调整。CYP3A5基因多态性检测采用聚合酶链反应-限制性片段长度多态性（PCR—RFLP）方法,50例肾移植受者分为＊1／＊1型（12例）、＊1／＊3型（16例）、＊3／＊3型（22例）共3组。比较6个月内FK506的血药浓度／剂量比。结果 肾移植术后7天、1月、3月、6月＊3／＊3型患者FK506的血药浓度／剂量比显著高于＊1／＊1型和＊1／＊3型（P〈0．05）。结论由于CYP3A5基因多态性影响,＊1／＊1型组的患者早期难以达到有效FK506目标血药浓度,应该提高该组患者的起始用药剂量,根据CYP3A5基因多态性作为FK506个体化用药的依据,可以减少早期急性排斥反应,提高肾移植的临床效果。     

CYP 3A5*3基因多态性对肾移植术后他克莫司药代动力学的影响

目的探讨CYP3A5*3基因多态性对肾移植术后他克莫司(免疫抑制药)剂量校正给药2h后浓度的影响。方法选取61例肾移植术后患者,用聚合酶链式反应-限制性片段长度多态性的方法,分析CYP 3A5*3基因型;用微粒酶联免疫吸附法,测定患者他克莫司浓度。并分析CYP 3A5*3基因多态性与他克莫司给药剂量、给药2h浓度(C2)及剂量校正给药2h后浓度(C2/D)的相关性。结果肾移植术后1周及1、3个月,CYP 3A5*1/*1 CYP 3A5*1/*3组和CYP3A5*3/*3组他克莫司剂量比较均无显著性差异。术后1周和1个月,2组间他克莫司C2比较无显著性差异;术后3个月,CYP 3A5*1/*1 CYP 3A5*1/*3组的C2显著低于CYP 3A5*3/*3组(P<0.05)。术后1周及1、3个月,CYP 3A5*1/*1 CYP 3A5*1/*3组的C2/D均明显低于CYP 3A5*3/*3组(P<0.05)。结论肾移植术后,他克莫司C2/D的个体化差异与患者CYP3A5*3基因型密切相关。     

CYP3A5*1-carrying graft liver reduces the concentration/oral dose ratio of tacrolimus in recipients of living-donor liver transplantation

OBJECTIVES: Tacrolimus is widely used for immunosuppressive therapy after organ transplantation, but its pharmacokinetics shows such great interindividual variation that control of its blood concentration is difficult. We have previously reported that an intestinal P-glycoprotein (MDR1) contributes to this variation as an absorptive barrier, but the role of hepatic metabolism is not clear. METHODS: In this study, we have evaluated the genotypes of MDR1 and cytochrome P450 (CYP) 3A in donor and recipient, and the influence of polymorphisms on mRNA expression and the tacrolimus concentration/dose (C/D) ratio in recipients of living-donor liver transplantation (LDLT). RESULTS: The expression level of MDR1 and tacrolimus C/D ratio were not affected by either MDR1 C3435T or G2677T/A. The CYP3A4*1B genotype was not detected, but the CYP3A5*3 genotype had an allelic frequency of 76.3%. The mRNA level of CYP3A5 was significantly reduced by the *3/*3 genotype, and the tacrolimus C/D ratio was decreased in recipients engrafted with partial liver carrying CYP3A5*1/*1 genotype. An analysis of the combination of intestinal MDR1 level and liver CYP3A5 genotype revealed that the tacrolimus C/D ratio was lower in the group with higher MDR1 levels regardless of CYP3A5 genotype during postoperative week 1. CONCLUSIONS: These results indicate that in recipients of LDLT, the pharmacokinetics of tacrolimus is influenced by flux via P-glycoprotein in the intestine during the first week; after that, it is mostly the hepatic metabolism that contributes to the excretion of tacrolimus, and carriers of the CYP3A5*1/*1 genotype require a high dose of tacrolimus to achieve the target concentration.     

Interaction between tacrolimus and lansoprazole, but not rabeprazole in living-donor liver transplant patients with defects of CYP2C19 and CYP3A5

We report different effects of administration of proton pump inhibitors on tacrolimus blood concentration in two living-donor liver transplant patients. In case 1, a 51-year-old man with liver cirrhosis due to hepatitis C virus underwent living-donor liver transplantation, and tacrolimus was orally administered. Omeprazole (40 mg/day) was introduced intravenously between postoperative days 5 and 6, and oral lansoprazole (30 mg/day) was introduced from day 6, leading to an increase in the concentration/dose ratio of tacrolimus from day 10. In case 2, a 41-year-old living-donor liver transplant woman received tacrolimus, and co-administered with omeprazole (40 mg/day) intravenously during 7 days immediately after surgery. During this period, trough concentration of tacrolimus was high, but the concentration/dose ratio of tacrolimus was gradually decreasing with time. Switched to rabeprazole (10 mg/day) orally on the postoperative 8th day, the concentration/dose ratio of tacrolimus remained low, indicating little drug-drug interaction between tacrolimus and rabeprazole. In both cases, the genotypes of CYP2C19 and CYP3A5 were defective both in the graft liver and in the native intestine. A drug-drug interaction between rabeprazole and tacrolimus was not observed in this case study presented, suggesting that this combination could be safely used in tacrolimus therapy after liver transplantation.     

CYP3A5基因型对中国肾移植术后患者体内他克莫司缓释剂型药动学参数的影响

目的研究CYP3A5基因型对中国肾移植术后患者体内他克莫司缓释剂型药动学参数的影响。方法采用化学发光免疫法检测20例肾移植术后患者在服用缓释(10例)和普通剂型(10例)他克莫司后的全血浓度;采用聚合酶链反应-限制性片段长度多态法检测服用缓释剂型他克莫司患者的CYP3A5基因型;缓释剂型组检测0~24 h的11个时间点的血药浓度,而普通剂型检测0~12 h内的10个时间点的血药浓度。结果无剂量校正的缓释剂型组的AUC_(0~24 h)为普通剂型组AUC_(0~12 h)的1.78倍,有剂量校正的缓释剂型组的C_0为普通剂型的60%,其余药动学参数差异无显著性;缓释剂型中慢代谢型组的C_(max)、AUC_(0~24 h)和C_0分别为快代谢型组的1.75、1.96、2.49倍(无剂量校正)以及1.80、2.34和2.64倍(有剂量校正);缓释剂型组的C_0与AUC_(0~24 h)的相关性良好。结论他克莫司普通剂型转换至缓释剂型时应该注意上调给药剂量,同时缓释剂型应结合CYP3A5的基因型检测,确保C_0值在治疗窗范围内。     

Impact of MDR1 and CYP3A5 on the oral clearance of tacrolimus and tacrolimus-related renal dysfunction in adult living-donor liver transplant patients

OBJECTIVE: The potential influence of the multidrug resistance 1 (MDR1) gene and the cytochrome P450 (CYP) genes, CYP3A4 and CYP3A5, on the oral clearance (CL/F) of tacrolimus in adult living-donor liver transplant patients was examined. Furthermore, the development of renal dysfunction was analyzed in relation to the CYP3A5 genotype. METHODS: Sixty de novo adult liver transplant patients receiving tacrolimus were enrolled in this study. The effects of various covariates (including intestinal and hepatic mRNA levels of MDR1 and CYP3A4, measured in each tissue taken at the time of transplantation, and the CYP3A5*3 polymorphism) on CL/F during the first 50 days after surgery were investigated with the nonlinear mixed-effects modeling program. RESULTS: CL/F increased linearly until postoperative day 14, and thereafter reached a steady state. The initial CL/F immediately after liver transplantation was significantly affected by the intestinal MDR1 mRNA level (P<0.005). Furthermore, patients carrying the CYP3A5*1 allele in the native intestine, but not in the graft liver, showed a 1.47 times higher (95% confidence interval, 1.17-1.77 times, P<0.005) recovery of CL/F with time than patients having the intestinal CYP3A5*3/*3 genotype. The cumulative incidence of renal dysfunction within 1 year after transplantation, evaluated by the Kaplan-Meier method, was significantly associated with the recipient's but not donor's CYP3A5 genotype (*1/*1 and *1/*3 vs. *3/*3: recipient, 17 vs. 46%, P<0.05; donor, 35 vs. 38%, P=0.81). CONCLUSION: These findings suggest that the CYP3A5*1 genotype as well as the MDR1 mRNA level in enterocytes contributes to interindividual variation in the CL/F of tacrolimus in adult recipients early after living-donor liver transplantation. Furthermore, CYP3A5 in the kidney may play a protective role in the development of tacrolimus-related nephrotoxicity.     

CYP3A5和ABCB1基因多态性对肾移植患者术后初期他克莫司剂量、浓度及肾功能的影响

目的研究CYP3A5和ABCB1基因多态性对肾移植患者术后初期他克莫司剂量、浓度以及肾功能的影响。方法以200例肾移植患者为研究对象,使用聚合酶链式反应(PCR)-限制性内切片段长度多态性(RFLP)法和测序法检测患者CYP3A5*3和ABCB1(C1236T、G2677T/A、C3435T)基因型,比较肾移植术后28 d内不同基因型患者之间他克莫司血药浓度(C)、剂量(D)、浓度剂量比(C/D)以及肾功能(血清肌酐和胱抑素C水平)的差异。结果 CYP3A5非表达组(CYP3A5*3*3型)的C和C/D在术后7、14、21和28 d均显著高于CYP3A5表达组(CYP3A5*1*1和CYP3A5*1*3型)(P <0.05,P<0.01)。ABCB1 1236基因多态性对CYP3A5表达组患者的他克莫司C、D及C/D均没有显著影响;对于CYP3A5非表达组,ABCB1 1236 CT和TT型患者他克莫司的D及C/D有显著性差异。对于CYP3A5表达组,ABCB1 3435 TT型患者他克莫司的C和D显著低于CC型和CT型患者(P <0.05);而在CYP3A5非表达组中,ABCB1 3435 TT型患者的他克莫司D显著低于CT型。对肾功能的影响:ABCB11236和2677基因型对CYP3A5表达组和非表达组肾功能均没有显著影响。对于CYP3A5非表达组,ABCB1 3435 TT型患者移植后第7或14日肌酐和胱抑素C水平显著高于CC和CT型患者(P <0.05)。结论肾移植术后初期,CYP3A5*3、ABCB1 C1236T和ABCB1 C3435T基因多态性影响他克莫司C和D,ABCB1 C3435T基因多态性对肾功能有影响。     

Prediction of tacrolimus metabolism and dosage requirements based on CYP3A4 phenotype and CYP3A5*3 genotype in Chinese renal transplant recipients

Aim:

To examine how the endogenous CYP3A4 phenotype and CYP3A5^*3 genotype of Chinese renal transplant recipients influenced the dose-corrected trough concentration (C₀/D) and weight-corrected daily dose (D/W) of tacrolimus.

Methods:

A total of 101 medically stable kidney transplant recipients were enrolled, and their blood and urine samples were gathered. The endogenous CYP3A4 phenotype was assessed by the ratio of 6β-hydroxycortisol and 6β-hydroxycortisone to cortisol and cortisone in urine. CYP3A5^*3 genotype was determined using PCR-RELP.

Results:

In overall renal transplant recipients, a multiple regression analysis including the endogenous CYP3A4 phenotype, CYP3A5^*3 genotype and post-operative period accounted for 60.1% of the variability in C₀/D ratio; a regression equation consisting of the endogenous CYP3A4 phenotype, post-operative period, body mass index, CYP3A5^*3 genotype, gender, total bilirubin and age explained 61.0% of the variability in D/W ratio. In CYP3A5^*3/^*3 subjects, a combination of the endogenous CYP3A4 phenotype, post-operative period and age was responsible for 65.3% of the variability in C₀/D ratio; a predictive equation including the endogenous CYP3A4 phenotype, post-operative period, body mass index, gender and age explained 61.2% of the variability in the D/W ratio. Base on desired target range of tacrolimus trough concentrations, individual daily dosage regimen was calculated, and all the observed daily doses were within the predicted range.

Conclusion:

This study provides the equations to predict tacrolimus metabolism and dosage requirements based on the endogenous CYP3A4 phenotype, CYP3A5^*3 genotype and other non-genetic variables.     

Effect of long-term tacrolimus immunosuppression on renal function in liver transplant recipients

STUDY OBJECTIVES: To describe changes in renal function occurring after long-term treatment with tacrolimus in clinically stable liver transplant recipients, and to identify risk factors for a clinically significant decline in renal function in these patients. DESIGN: Retrospective cohort study. Setting. University medical center. Patients. Four hundred thirty-two patients aged 18 years or older who underwent liver transplantation between January 1, 1996, and December 31, 2000, and received tacrolimus as part of their immunosuppressive treatment regimen. MEASUREMENTS AND MAIN RESULTS: Six hundred patients were identified from an electronic records review. Those who received multiorgan transplants, were not receiving their first liver transplant, or died during the hospitalization were excluded from the study. Outcomes measured were change in mean glomerular filtration rate (GFR) up to 5 years after transplantation, and proportion of patients with a decline in GFR of 30% or greater from baseline to the last recorded serum creatinine level. Covariates that affected this decline were identified using a logistic regression model. Patients were followed for a mean +/- SD of 3.7 +/- 2.0 years. Mean GFR showed a statistically significant decline from baseline to end of follow-up (67.7 +/- 25.6 vs 58.4 +/- 26.5 ml/min/1.73 m(2), p<0.001). The GFR declined by 30% or more in 154 (35.6%) patients. Increasing age (odds ratio [OR] = 1.03, p=0.020), female sex (OR = 1.92, p=0.006), higher baseline GFR (OR = 1.03, p<0.001), and diagnosis of diabetes mellitus (OR = 1.74, p=0.059) were identified as predictors of this outcome. CONCLUSION: After the acute posttransplantation period, liver transplant recipients given long-term treatment with tacrolimus experienced only small changes in GFR over time. Patients with diabetes and women had the highest risk of experiencing a clinically significant decline in renal function.     

Population pharmacokinetics of tacrolimus in adult recipients receiving living-donor liver transplantation

OBJECTIVE: To characterize the pharmacokinetics of tacrolimus in adult recipients receiving living-donor liver transplantation (LDLT). METHODS: Thirty-five patients were given tacrolimus as 18- to 60-h intravenous infusions after surgery, followed by a 4-week course of oral dose therapy (at 0900 hours and 2100 hours). Blood samples were collected daily in the morning (0800 hours) beginning the day after surgery. Whole blood concentration data were evaluated by nonlinear mixed-effect modeling using the program NONMEM and were characterized using a one-compartment model. RESULTS: The clearance (CL, l h(-1)) was related to the grafted hepatic weight, postoperative days (POD), and hepatic and renal dysfunction. Interindividual variabilities in CL, volume of distribution (V), and bioavailability (F) were 57.4%. 39.7%, and 63.0%, respectively, and the correlation between individual CL and F was 0.776. Residual intraindividual variability was 2.9 ng ml(-1). Based on the estimated final parameters, a typical recipient of LDLT with grafted hepatic weight of 600 g and normal hepatic and renal function would have a CL of 0.737 l h(-1) on POD 0 and 1.14 l h(-1) on POD 30, V of 1.52 l kg(-1) and F of 6.8%. CONCLUSIONS: Nonlinear mixed-effect modeling was useful for analysis of pharmacokinetic characteristics of tacrolimus in LDLT patients. Immediately after surgery, patients receiving LDLT showed a smaller CL value than other transplant patients, and CL value increased with POD within 30 days after surgery. The estimated population pharmacokinetic parameters can be applied for a priori dosage calculations in adult patients with LDLT.     

Clinical and genetic factors affecting tacrolimus trough levels and drug-related outcomes in Korean kidney transplant recipients

Purpose

The purpose of this study was to characterize the effects of clinical and genetic variables on the pharmacokinetics and complications of tacrolimus during the first year after kidney transplantation.

Methods

One hundred and thirty-two Korean kidney recipients who received tacrolimus were genotyped for ABCB1 (exons 12, 21, and 26) and CYP3A5 (intron 3). Tacrolimus trough levels, dose, or dose-adjusted trough levels and complications were compared among patients during the early stage (3, 7, 14, 30, and 90?days) and up to 1?year according to the genotypes.

Results

A donor source-adjusted linear mixed model with multilevel analysis adjusting for age, body weight, hematocrit, and serum creatinine showed that CYP3A5 genotype is associated with dose-adjusted level of tacrolimus (p?ABCB1 polymorphisms on the pharmacokinetics or complications of tacrolimus was less certain in our study. The incidence of acute rejections was significantly higher in recipients of cadaveric donor kidney (p?Conclusions A generalized estimating equation model analysis showed that alopecia and hyperlipidemia were associated with dose-adjusted level of tacrolimus (p?CYP3A5 variants along with significant clinical covariates may be useful in individualizing tacrolimus therapy in kidney transplantation patients.     

CYP3A5~* 3基因多态性与肾移植术后环孢素肝损伤的相关性

目的:研究肾移植术后患者CYP3A5*3基因多态性对环孢素(CsA)所致肝损伤的影响。方法:采用PCR-RFLP(聚合酶链反应-限制性片段长度多态性)方法对359名肾移植患者进行CYP3A5*3基因型检测;荧光偏振免疫法检测肾移植患者CsA血浓度,根据肾移植患者发生肝脏损伤的情况分为CsA肝损伤组、其他原因肝损伤组和对照组。结果:在359名肾移植患者中,CYP3A5*3突变等位基因频率为73.5%。与对照组相比,CsA肝损伤组和其他原因肝损伤组的CYP3A5*3/*3分布频率明显增高(P<0.05或0.01),CsA肝损伤组的CYP3A5*3/*3分布频率亦明显高于其他原因肝损伤组(P<0.01)。肾移植术后1个月和3个月,CYP3A5*3/*3组和*1/*3组的CsA血谷浓度均明显高于*1/*1组(P<0.05)。术后7d、1个月、3个月、6个月,CsA肝损伤组的CsA谷浓度明显高于对照组(P<0.05或P<0.01)。Logistic回归模型显示,*3/*3基因型和术后6个月高CsA谷浓度是CsA肝损伤发生的危险因素。结论:CYP3A5*3基因多态性对肾移植患者CsA所致肝损伤有明显影响,携带*3突变基因...     

The effect of CYP3A5 and MDR1 (ABCB1) polymorphisms on cyclosporine and tacrolimus dose requirements and trough blood levels in stable renal transplant patients

Cyclosporine and tacrolimus are immunosuppressive drugs largely used in renal transplantation. They are characterized by a wide inter-individual variability in their pharmacokinetics with a potential impact on their therapeutic efficacy or induced toxicity. CYP3A5 and P-glycoprotein appear as important determinants of the metabolism of these drugs. The objective of this study was to investigate the effect of CYP3A5 and MDR1 (ABCB1) polymorphisms on cyclosporine and tacrolimus dose requirements and trough blood concentrations in stable transplant patients. Stable renal transplant recipients receiving cyclosporine (n = 50) or tacrolimus (n = 50) were genotyped for CYP3A5*3 and *6, and MDR1 C1236T, G2677T/A and C3435T. Dose-adjusted trough blood levels (ng/ml per mg/kg body weight) as well as doses (mg/kg body weight) required to achieve target blood concentrations were compared among patients according to allelic status for CYP3A5 and MDR1. Dose-adjusted trough concentrations were three-fold and 1.6-fold higher in CYP3A5*3/*3 patients than in CYP3A5*1/*3 patients for tacrolimus and cyclosporine, respectively. In the case of tacrolimus, the difference was even more striking when considering CYP3A5*1/*1 patients showing dose-adjusted trough concentrations 5.8-fold lower than CYP3A5*3/*3 patients. For both drugs, no association was found between trough blood concentrations or dose requirement and MDR1 genotype. Multiple regression analyses showed that CYP3A5*1/*3 polymorphism explained up to 45% of the variability in dose requirement in relation to tacrolimus use. Given the importance of rapidly achieving target blood concentrations after transplantation, further prospective studies should consider the immediate post-graft period and assess the influence of this specific polymorphism. Beside non-genetic factors (e.g. steroids dosing, drugs interactions), CYP3A5 pharmacogenetic testing performed just before transplantation could contribute to a better individualization of immunosuppressive therapy.     

Recipient ABCB1, donor and recipient CYP3A5 genotypes influence tacrolimus pharmacokinetics in liver transplant cases

BackgroundEffective immunosuppression through optimization of trough levels tacrolimus reduces post-transplant mortality rate in liver transplant cases.MethodsMeta-analysis was carried out to evaluate how donor/recipient CYP3A5 (n = 678) and recipient ABCB1 (n = 318) genotypes influence tacrolimus pharmacokinetics till one-month of transplantation.ResultsThe donor CYP3A5*3/*3 genotype exhibited higher concentration/dose (C/D) ratio of tacrolimus in week 1 (mean difference: 65.04, 95% CI: 15.30–114.79 ng/ml/mg/kg), week 2 (mean difference: 21.7, 95% CI: 12.6–30.9 ng/ml/mg/kg) and week 4 (mean difference: 43.28, 95% CI: 17.09 – 69.49 ng/ml/mg/kg) compared to *1/*1 and *1/*3 genotypes. The recipient CYP3A5 *3/*3 genotype did not showed significant difference in tacrolimus C/D ratio in week 1 compared to other two genotypes. However, week 2 (mean difference: 44.16, 95% CI: 3.68–84.65 ng/ml/mg/kg) and week 4 (mean difference: 43.74, 95% CI: 12.50–75.00 ng/ml/mg/kg) availability was higher in *3/*3 mutant recipients. However, the recipient ABCB1 3435 C > T polymorphism has no significant influence on tacrolimus pharmacokinetics till one month of transplant.ConclusionsThe donor and recipient CYP3A5*3 polymorphism influences tacrolimus pharmacokinetics in the first month post-transplantation, whereas the association with recipient ABCB1 3435 C > T is inconclusive.     

Lack of tacrolimus circadian pharmacokinetics and CYP3A5 pharmacogenetics in the early and maintenance stages in Japanese renal transplant recipients

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Circadian variations of tacrolimus pharmacokinetics are controversial.
• Also, the pharmacokinetics has time-dependent variability, such as a decrease in oral clearance and increase in the dose-adjusted AUC after transplantation.
• Although the CYP3A5 polymorphism is associated with tacrolimus pharmacokinetics, differences in the influence of this gene on the pharmacokinetics between the early and maintenance stages have not yet been clarified.

WHAT THIS STUDY ADDS

• Tacrolimus pharmacokinetics did not show circadian variation in either the early or maintenance stage with our designated-time administration strategy.
• Based on previous results and our own findings, the interval between food consumption and tacrolimus administration might influence the interindividual and interinstitutional variability of tacrolimus chronopharmacokinetics.
• The CYP3A5 polymorphism may be associated with the time-dependent changes in tacrolimus oral clearance.

AIMS

We investigated whether tacrolimus pharmacokinetics shows circadian variation and the influence of the CYP3A5 A6986G polymorphism on the pharmacokinetics in both the early and maintenance stages after renal transplantation.

METHODS

Tacrolimus was administered twice daily at specified times (09.00 and 21.00 h) throughout the pre- and post-transplant period according to the trough-targeting strategy. Fifty recipients with stable graft function were studied on day 28 and beyond 1-year post transplantation. Whole blood samples were collected prior to and 1, 2, 3, 4, 6, 9 and 12 h after both the morning and evening doses during hospitalization.

RESULTS

Tacrolimus pharmacokinetics did not show circadian variation in either the early or maintenance stage [AUC_0–12 197.1 (95% confidence interval 182.9, 212.3) in daytime vs. 203.6 ng h ml⁻¹ (189.8, 217.4) in the night-time at day 28, 102.0 (92.1, 111.9) vs. 107.7 (97.9, 117.5) at 1 year, respectively]. In CYP3A5 *1 allele carriers (CYP3A5 expressers), body weight-adjusted oral clearance was markedly decreased from the early stage to the maintenance stage [0.622 (0.534, 0.709) to 0.369 l h⁻¹ kg⁻¹ (0.314, 0425)] compared with a smaller decrease [0.368 (0.305, 0.430) to 0.305 (0.217, 0.393)] in CYP3A5 non-expressers; however, the CYP3A5 genetic variation did not influence tacrolimus chronopharmacokinetics.

CONCLUSION

Equivalent daytime and night-time tacrolimus pharmacokinetics were achieved during both the early and maintenance stages with our specified-time administration strategy. The CYP3A5 polymorphism may be associated with the time-dependent changes in the oral clearance of tacrolimus, suggesting that genotyping of this polymorphism is useful for determining the appropriate dose of tacrolimus in both the early and maintenance stages after renal transplantation.     

CYP3A4*18B和CYP3A5*3基因多态性对肾移植患者他克莫司剂量及浓度的影响

研究CYP3A5*3和CYP3A4*18B基因突变对他克莫司血药浓度/剂量×体表面积(C/D′)、不良反应和急性排斥反应的影响。采用聚合酶链反应(PCR)和限制性内切片段长度多态性(RFLP)方法检测227例肾移植患者CYP3A5*3和CYP3A4*18B基因型,比较不同基因型患者之间他克莫司的C/D′值、不良反应和急性排斥反应发生率的差异。测得CYP3A4*18B和CYP3A5*3基因型在肾移植患者中的突变频率分别为30.8%和74.2%。消除CYP3A5*3等位基因影响后,CYP3A4*18B各基因型间他克莫司C/D′值无显著性差异(P>0.05);而消除CYP3A4*18B等位基因影响后,CYP3A5*1/*1和*1/*3基因型患者的他克莫司C/D′值显著低于*3/*3(P<0.01)。CYP3A4*18B和CYP3A5*3基因多态性与不良反应和排斥反应间差异无统计学意义(P>0.05)。     

Required transient dose escalation of tacrolimus in living-donor liver transplant recipients with high concentrations of a minor metabolite M-II in bile

The profiles of tacrolimus metabolites in the whole blood and bile were examined in two living-donor liver transplant patients, who transiently required higher doses of tacrolimus. Even when the 16 mg/day or oral 10 mg/day and intravenous infusion of 0.5 mg/day of tacrolimus were administered, its trough level in each patient did not reach over 15 ng/mL. By use of liquid chromatography-tandem mass spectrometry/mass spectrometry methods, a minor metabolite M-II was found to be a major metabolite both in blood and bile in these cases. However, a primary metabolite M-I was confirmed as the majority in the bile of other 8 control cases. Each graft liver and native intestine carried CYP3A5*1/*3 or *3/*3 and *1/*3 or *1/*3, respectively. Therefore, the CYP3A5 genotype could not explain the present phenomena. After removing the bile drainage tube to allow the bile flow into intestine, the required doses of tacrolimus were decreased to around 20% compared to each maximum dosage. In conclusion, a minor metabolite M-II was first found in the human bile, suggesting that the appearance of M-II in bile could associate with the extensive metabolism of tacrolimus and/or the requirement of larger oral dosage.     

Effect of CYP3A5 polymorphism on tacrolimus metabolic clearance in vitro.

Previous investigations of solid organ transplant patients treated with tacrolimus showed that individuals carrying a CYP3A5*1 allele have lower dose-adjusted trough blood concentrations compared with homozygous CYP3A5*3 individuals. The objective of this investigation was to quantify the contribution of CYP3A5 to the hepatic and renal metabolic clearance of tacrolimus. Four primary tacrolimus metabolites, 13-O-desmethyl tacrolimus (13-DMT) (major), 15-O-desmethyl tacrolimus, 31-O-desmethyl tacrolimus (31-DMT), and 12-hydroxy tacrolimus (12-HT), were generated by human liver microsomes and heterologously expressed CYP3A4 and CYP3A5. The unbound tacrolimus concentration was low (4-15%) under all incubation conditions. For CYP3A4 and CYP3A5, V(max) was 8.0 and 17.0 nmol/min/nmol enzyme and K(m,u) was 0.21 and 0.21 muM, respectively. The intrinsic clearance of CYP3A5 was twice that of CYP3A4. The formation rates of 13-DMT, 31-DMT, and 12-HT were >or=1.7-fold higher, on average, in human liver microsomes with a CYP3A5*1/*3 genotype compared with those with a homozygous CYP3A5*3/*3 genotype. Tacrolimus disappearance clearances were 15.9 +/- 9.8 ml/min/mg protein and 6.1 +/- 3.6 ml/min/mg protein, respectively, for the two genotypes. In vitro to in vivo scaling using both liver microsomes and recombinant enzymes yielded higher predicted in vivo tacrolimus clearances for patients with a CYP3A5*1/*3 genotype compared with those with a CYP3A5*3/*3 genotype. In addition, formation of 13-DMT was 13.5-fold higher in human kidney microsomes with a CYP3A5*1/*3 genotype compared with those with a CYP3A5*3/*3 genotype. These data suggest that CYP3A5 contributes significantly to the metabolic clearance of tacrolimus in the liver and kidney.