Effects of Wuzhi Capsules on Blood Concentration of Tacrolimus in Renal Transplant Recipients

CYP3A5 Genotype-Dependent Drug-Drug Interaction Between Tacrolimus and Voriconazole in Chinese Kidney Transplant Patients

BACKGROUND

The effect of drug-drug interaction (DDI) between tacrolimus and voriconazole on the pharmacokinetics of tacrolimus in different CYP3A5 genotypes has not been reported in previous studies.

OBJECTIVE

The objective of this study was to investigate whether CYP3A5 genotype could influence tacrolimus-voriconazole DDI in Chinese kidney transplant patients.

METHODS

All kidney transplant patients were divided into combination and non-combination groups based on whether tacrolimus was combined with or without voriconazole. Each group was subdivided into CYP3A5 expresser (CYP3A5*1/*1 or CYP3A5*1/*3) and CYP3A5 nonexpresser (CYP3A5*3/*3). A retrospective analysis compared tacrolimus dose (D)-corrected trough concentrations (C0) (C0/D) between combination and non-combination groups, respectively. Tacrolimus C0/D was also compared between CYP3A5 expresser and nonexpresser in both groups.

RESULTS

The C0/D values of tacrolimus were significantly different between CYP3A5 expresser and nonexpresser in combination group (378.20 [219.38, 633.48] ng/mL/[mg/kg/d] vs 720.00 [595.35, 1681.50] ng/mL/[mg/kg/d], P = 0.0010). Either in CYP3A5 expresser or nonexpresser, we found a statistically significant difference in tacrolimus C0/D between combination and non-combination group (P < 0.0001). The increase in CYP3A5 nonexpresser was 1.38 times higher than that in CYP3A5 expresser (320.93% vs 232.19%).

CONCLUSION AND RELEVANCE

The median C0/D values were 90.38% higher in kidney transplant recipients with CYP3A5*3/*3 genotype than in those with CYP3A5*1/*1 or CYP3A5*1/*3 genotype when treated with both tacrolimus and voriconazole. A CYP3A5 genotype-dependent DDI was found between tacrolimus and voriconazole. Therefore, personalized therapy accounting for CYP3A5 genotype detection and therapeutic drug monitoring is necessary for kidney transplant patients when treating with tacrolimus and voriconazole.

Evidence of the interactions between immunosuppressive drugs used in autoimmune rheumatic diseases and Chinese herbal medicine: A scoping review

OBJECTIVES

Chinese herbal medicine (CHM) has been shown to be effective in autoimmune rheumatic diseases, but harmful herb-drug interactions might be inherent. We aim to review the evidence regarding herb-drug interactions between immunosuppressive drugs used in autoimmune rheumatic diseases and CHM.

METHODS

We searched PubMed, EMBASE and CINAHL from inception till 30 April 2023 using keywords that encompassed 'herb-drug interactions', 'herbs' and 'immunosuppressants'. Articles were included if they contained reports about interactions between immunosuppressive drugs used in the treatment of rheumatic diseases with CHM. Level of evidence for each pair of interaction was graded using the algorithm developed by Colalto.

RESULTS

A total of 65 articles and 44 unique pairs of interactions were identified. HDIs were reported for cyclophosphamide, cyclosporine, tacrolimus, methotrexate, mycophenolic acid, glucocorticoids, sulfasalazine, tofacitinib and biologic disease-modifying antirheumatic drugs. Among these, cyclosporine (n = 27, 41.5%) and tacrolimus (n = 19, 29.2%) had the highest number of documented interactions. Hypericum perforatum had the highest level of evidence of interaction with cyclosporine and tacrolimus. Consumption reduced the bioavailability and therapeutic effects of the drugs. Schisandra sphenanthera had the highest level of evidence of interaction with tacrolimus and increased the bioavailability of the drug. Majority of the articles were animal studies.

CONCLUSION

Overall level of evidence for the included studies were low, though interactions between cyclosporine, tacrolimus, Hypericum perforatum and Schisandra sphenanthera were the most and well-documented. Healthcare professionals should actively enquire about the concurrent use of CHM in patients, especially when drugs with a narrow therapeutic index are consumed.

Effects of Wuzhi Capsule on Whole-Blood Tacrolimus Concentration Levels: A Systematic Review and Meta-Analysis

BACKGROUND

Wuzhi Capsule (WZC) is a traditional Chinese medicinal herb widely used to treat drug-induced hepatitis or liver dysfunction and is usually prescribed in China to increase tacrolimus concentration. Several studies with small sample sizes have shown that WZC can increase tacrolimus concentration levels in clinical practice. This study aimed to evaluate the effect of WZC on whole-blood tacrolimus concentration levels and safety.

METHODS

We searched 7 databases for randomized clinical trials (RCTs) and observational studies (OSs) comparing whole-blood tacrolimus concentration levels between WZC and non-WZC treatments. Data analysis was performed using Review Manager version 5.3. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines.

RESULTS

Eleven studies involving 6 RCTs and 5 OSs were included. The meta-analysis indicated that whole-blood tacrolimus concentration levels in the WZC group was significantly higher than that of the non-WZC group [weighted mean difference = 1.38, 95% CI (confidence interval), 1.21-1.56, P < 0.001], and similar results were shown in all the subgroups of follow-up time, different primary disease, and different WZC doses. In the self-control OSs, the whole-blood tacrolimus concentration levels in the WZC group was significantly higher than the non-WZC group (weighted mean difference = 1.17, 95% CI, 0.71-1.64, P < 0.001). WZC was generally well tolerated and there was no significant difference in the incidence of adverse reactions between the 2 groups.

CONCLUSIONS

WZC can increase whole-blood tacrolimus concentration levels. This may be an economical and practical treatment choice for patients, especially those with poor oral tacrolimus absorption capabilities. Nevertheless, RCTs and OSs with large sample sizes and high quality are needed in the future to confirm these positive results.

Effects of WuZhi preparations on tacrolimus in pediatric and adult patients carrying the CYP3A5*1 allele of heart transplant during the early period after transplantation

AIM

Wuzhi preparations (WZP) are commonly administrated with tacrolimus (TAC) in China to improve the liver function and increase the exposure of TAC. This study aims to investigate the effects of WZP on TAC in pediatric heart transplantation (HTx) patients carrying the CYP3A5*1 allele during the early period after transplantation and also make a comparison with these effects in adult recipients.

METHODS

A total of 81 recipients with CYP3A5*1 allele were included and divided into the pediatric group (n = 29) and adult group (n = 52). The changes in TAC dose-corrected trough blood concentrations (C0 /D), dose requirement as well as intra-patient variability(IPV) of C0 /D after co-therapy with WZP were evaluated.

RESULTS

The TAC C0 /D was significantly increased 1.7 and 1.8 times after co-administration of WZP in the pediatric and adult groups, respectively. We further analyzed the pediatric patients, found that no statistical difference was observed in TAC C0 /D before and after co-therapy with WZP in children <6 years old. The changes of C0 /D increased with the dose of the active ingredient (Schisantherin A) in adult patients, but not in pediatric patients. TAC IPV was reduced by 10.5% in pediatric patients and 4.8% in adult patients when co-administrated with WZP. Furthermore, after taking WZP, the AST and TB were dramatically lowered in pediatric recipients.

CONCLUSION

Our study is the first attempt to demonstrate the effects of WZP on TAC in pediatric HTx recipients. By comparing these effects to those observed in adult recipients, valuable insights can be gained regarding the efficacy and potential benefits of WZP in the pediatric population.

Effect of Wuzhi preparations on tacrolimus in CYP3A5 expressers during the early period after transplantation: A real-life experience from heart transplant recipients

BACKGROUND

Genetic polymorphisms and drug interactions are associated with tacrolimus exposure. This study aimed to evaluate the effect of Wuzhi (WZ) preparations on tacrolimus (TAC) concentration and dose requirements in heart transplant recipients with the CYP3A5*1 allele during the early period after transplantation.

METHODS

A total of 167 adult heart transplant recipients with the CYP3A5*1 allele were included and divided into the WZ group (n = 115) and the WZ-free group (n = 52). Blood trough concentrations of TAC were detected and the dose-adjusted concentration (C₀/D) and dose requirement for achieving the TAC therapeutic range were compared between the two groups. The change in C₀/D and dose of TAC were evaluated before and after co-administration with WZ preparations.

RESULTS

No significant differences in TAC C₀/D and dose requirement were observed between the WZ and WZ-free groups. However, the TAC C₀/D in the WZ group was significantly increased an average of 2.10-fold after co-administration of WZ. Moreover, the degree of elevation was related to the dose of the active ingredient (Schisantherin A). Furthermore, ALT, AST, and TB levels were significantly reduced after administration of WZ preparations.

CONCLUSION

Co-administration of the WZ/TAC preparation, in heart transplant recipients carrying the CYP3A5*1 allele, considerably increased TAC concentration (C₀/D) while decreased high levels of leading indicators in the liver function. More importantly, the effect of the WZ/TAC preparation on C₀/D was a dose-dependent event. However, our finding needs to be further confirmed in a larger sample size.

Controversial Interactions of Tacrolimus with Dietary Supplements, Herbs and Food

Tacrolimus is an immunosuppressive calcineurin inhibitor used to prevent rejection in allogeneic organ transplant recipients, such as kidney, liver, heart or lung. It is metabolized in the liver, involving the cytochrome P450 (CYP3A4) isoform CYP3A4, and is characterized by a narrow therapeutic window, dose-dependent toxicity and high inter-individual and intra-individual variability. In view of the abovementioned facts, the aim of the study is to present selected interactions between tacrolimus and the commonly used dietary supplements, herbs and food. The review was based on the available scientific literature found in the PubMed, Scopus and Cochrane databases. An increase in the serum concentration of tacrolimus can be caused by CYP3A4 inhibitors, such as grapefruit, pomelo, clementine, pomegranate, ginger and turmeric, revealing the side effects of this drug, particularly nephrotoxicity. In contrast, CYP3A4 inducers, such as St. John’s Wort, may result in a lack of therapeutic effect by reducing the drug concentration. Additionally, the use of Panax ginseng, green tea, Schisandra sphenanthera and melatonin in patients receiving tacrolimus is highly controversial. Therefore, since alternative medicine constitutes an attractive treatment option for patients, modern healthcare should emphasize the potential interactions between herbal medicines and synthetic drugs. In fact, each drug or herbal supplement should be reported by the patient to the physician (concordance) if it is taken in the course of immunosuppressive therapy, since it may affect the pharmacokinetic and pharmacodynamic parameters of other preparations.

The pharmacokinetic study of tacrolimus and Wuzhi capsule in Chinese liver transplant patients

Objectives: Wuzhi Capsule (WZC) is often administrated with tacrolimus in liver transplant patients to reduce the toxicity of tacrolimus and relieve the financial burden of patients. We aimed to investigate the interaction between Wuzhi Capsule (WZC) and tacrolimus in liver transplant patients.

Methods: We applied the LC-MS/MS analytical method previously established to study the pharmacokinetic characteristics of the analytes in 15 liver transplant patients. CYP3A5 genotypes were determined in 15 donors and recipients, and they were categorized into CYP3A5 expressers and non-expressers respectively.

Results: The influences of CYP3A5 in donors and recipients on the pharmacokinetics of tacrolimus with or without WZC were also studied. We found that 1) WZC could influence the metabolism of tacrolimus, which shortened the Tmax of tacrolimus and decreased V/F and CL/F. 2) Moreover, our results showed that, in donors, the CL/F of tacrolimus were significantly lower in CYP3A5 (CYP3A5*1) expressers (decreased from 24.421 to 12.864) and non-expressers (decreased from 23.532 to 11.822) when co-administration with WZC. For recipients, the decreased trend of CL/F of tacrolimus was seen when co-administrated with WZC by 15.376 and 12.243 in CYP3A5 expressers and non-expressers, respectively.

Conclusion: In this study, the pharmacokinetics effects of WZC on tacrolimus were identified. The co-administration of WZC can increase the tacrolimus blood concentration in Chinese liver transplant patients in clinical practice.

Tacrolimus Concentration Is Effectively Predicted Using Combined Clinical and Genetic Factors in the Perioperative Period of Kidney Transplantation and Associated with Acute Rejection

Background

Tacrolimus has unpredictable pharmacokinetic (PK) characteristics, which are partially attributed to CYP3A5 polymorphism. The potential effects of clinical factors in the postoperative period of transplantation on tacrolimus PK and those of early tacrolimus PK variability on clinical outcomes are yet to be clarified.

Methods

We examined the genetic and clinical factors affecting early tacrolimus PK variability in 256 kidney transplant recipients. The relationships among tacrolimus exposure, graft function delay (DGF), and acute rejection (AR) were further explored. Findings. The CYP3A5 genotype were strongly associated with tacrolimus concentration/dose ratio (C₀/D). Additionally, ABCB1 (rs1045642 and rs2032582) and ABCC2 (rs3740066) were found to have potential independent effects on early tacrolimus C₀/D in multivariate analysis. Red blood counts and albumin level were the most significant clinical factors associated with tacrolimus C₀/D. Wuzhi capsule also exerted an effect on tacrolimus PK. A model combined with pharmacogenetic and clinical factors explained 43.4% tacrolimus PK variability compared with 16.3% on the basis of CYP3A5 genotype only. Notably, increasing tacrolimus concentrations in the early postoperative stage were associated with AR, but not DGF.

Conclusions

Combined analysis of genotype and specific clinical factors is important for the formulation of precise tacrolimus dose regimens in the early stage after kidney transplantation.

A Prediction Model for Tacrolimus Daily Dose in Kidney Transplant Recipients With Machine Learning and Deep Learning Techniques

Tacrolimus is a major immunosuppressor against post-transplant rejection in kidney transplant recipients. However, the narrow therapeutic index of tacrolimus and considerable variability among individuals are challenges for therapeutic outcomes. The aim of this study was to compare different machine learning and deep learning algorithms and establish individualized dose prediction models by using the best performing algorithm. Therefore, among the 10 commonly used algorithms we compared, the TabNet algorithm outperformed other algorithms with the highest R² (0.824), the lowest prediction error [mean absolute error (MAE) 0.468, mean square error (MSE) 0.558, and root mean square error (RMSE) 0.745], and good performance of overestimated (5.29%) or underestimated dose percentage (8.52%). In the final prediction model, the last tacrolimus daily dose, the last tacrolimus therapeutic drug monitoring value, time after transplantation, hematocrit, serum creatinine, aspartate aminotransferase, weight, CYP3A5, body mass index, and uric acid were the most influential variables on tacrolimus daily dose. Our study provides a reference for the application of deep learning technique in tacrolimus dose estimation, and the TabNet model with desirable predictive performance is expected to be expanded and applied in future clinical practice.

Effect of drug combination on tacrolimus target dose in renal transplant patients with different CYP3A5 genotypes

Various factors, including genetic polymorphisms, drug-drug interactions, and patient characteristics influence the blood concentrations of tacrolimus in renal transplant patients. In the present study, we established a population pharmacokinetic model to explore the effect of combined use of Wuzhi capsules/echinocandins and the patients' biochemical parameters such as hematocrit on blood concentrations and target doses of tacrolimus in renal transplant patients with different CYP3A5 genotypes. The aim of the study was to propose an individualized tacrolimus administration regimen for early renal transplant recipients.In this retrospective cohort study, we included 240 renal transplant recipients within 21 days of surgery (174 males and 66 females, mean age 39.4 years), who received tacrolimus alone (n = 54), in combination with Wuzhi capsules (99) or caspofungin (57) or micafungin (30). We collected demographic characteristics, clinical indicators, CYP3A5 genotypes, and 1950 steady-state trough concentrations of tacrolimus and included them in population pharmacokinetic model. An additional 110 renal transplant recipients and 625 steady-state trough concentrations of tacrolimus were included for external validation of the model. The population pharmacokinetic model was established and Monte Carlo was used to simulate probabilities for achieving the target concentration for individual tacrolimus administration.A two-compartment model of first-order absorption and elimination was developed to describe the population pharmacokinetics of tacrolimus. CYP3A5 genotypes and co-administration of Wuzhi capsules, as well as time after renal transplantation and hematocrit, were important factors affecting the clearance of tacrolimus. We found no obvious change in trend in the scatter plot of tacrolimus clearance rate vs. hematocrit. The Monte Carlo simulation indicated the following recommended doses of tacrolimus alone: 0.14 mg·kg^-1·d^-1 for genotype CYP3A5*1*1, 0.12 mg·kg^-1·d^-1 for CYP3A5*1*3, and 0.10 mg·kg^-1·d^-1 for CYP3A5*3*3. For patients receiving the combination with Wuzhi capsules, the recommended doses of tacrolimus were 0.10 mg·kg^-1·d^-1 for CYP3A5*1*1, 0.08 mg·kg^-1·d^-1 for CYP3A5*1*3, and 0.06 mg·kg^-1·d^-1 for CYP3A5*3*3 genotypes. Caspofungin or micafungin had no effect on the clearance of tacrolimus in renal transplant recipients.The population pharmacokinetics of tacrolimus in renal transplant patients was evaluated and the individual administration regimen of tacrolimus was simulated. For early kidney transplant recipients receiving tacrolimus treatment, not only body weight, but also CYP3A5 genotypes and drugs used in combination should be considered when determining the target dose of tacrolimus.

Population pharmacokinetics of tacrolimus in Chinese adult liver transplant patients

Tacrolimus is widely used in organ transplantation to prevent rejection. However, the narrow therapeutic window and the large inter-and intra-individual variability in the pharmacokinetics (PK) of tacrolimus make it difficult for individualization of dosing. This study aimed at developing a population pharmacokinetic model for estimating the oral clearance of tacrolimus in Chinese liver transplant patients, and identifying factors that contribute to the PK variability of tacrolimus. Data of 151 liver transplant patients who received tacrolimus were analyzed in this study. The population PK model was analyzed and the covariates including population demographic and biochemical characteristics, drug combination, and genetic polymorphism were explored using non-linear mixed-effects modeling approach. A single-compartment population PK model was developed, and the final model was CL/F = (14.6-2.38 × cytochrome P450 (CYP) 3A5-3.72 × WZC+1.04 × (POD/9)+2.48 × COR) × Exp(η_i ), where CYP3A5 was 1 for CYP3A5*3/*3, Wuzhi Capsule (WZC) was 1 when patients took tacrolimus combined with WZC, otherwise it was 0, corticosteroids (COR) was 1 when patients take tacrolimus combined with COR, otherwise, it was 0, POD was the post-operative day. Visual inspection and bootstrap indicated that the final model was stable and robust. In this study, we developed the first tacrolimus population PK model in Chinese adult liver transplant patients. We first determined the influence of WZC on tacrolimus in these people, which could provide useful PK information for the drug combination of tacrolimus and WZC. We also revealed the influence of genetic polymorphism of CYP3A5, POD, and a combination of COR on tacrolimus PK. Therefore, these significant factors should be taken into consideration in optimizing dosage regimens.

Genetic Polymorphisms Affecting Tacrolimus Metabolism and the Relationship to Post-Transplant Outcomes in Kidney Transplant Recipients

Background

Tacrolimus is a key drug in kidney transplantation with a narrow therapeutic index. However, whether tacrolimus exposure variability affects clinical outcomes and adverse reactions remains unknown.

Objective

Our study investigated the factors that influence tacrolimus exposure in kidney transplantation recipients and the relationship between tacrolimus concentration and clinical outcomes and adverse reactions.

Settings and Methods

We examined the effect of tacrolimus concentration on clinical outcomes and adverse reactions in 201 kidney transplantation recipients, and identified clinical and pharmacogenetic factors that explain tacrolimus exposure.

Results

The CYP3A5 genotype was clearly associated with dose-adjusted trough blood tacrolimus concentrations (C₀/D), whereas no significant difference was observed in patients with the CYP3A4*1B, CYP3A4*22, ABCB1, ABCC2, POR*28 or PXR alleles. Clinical factors such as red blood cell count, hemoglobin, and albumin were the most useful influence factors affecting tacrolimus C₀/D. Besides, Wuzhi capsule increased tacrolimus C₀/D in kidney transplantation recipients. Furthermore, higher tacrolimus concentrations were associated with higher diarrhea and post-transplant diabetes mellitus (PTDM) risk but not with acute rejection and chronic allograft kidney dysfunction.

Conclusion

Clinical factors, medication, and CYP-enzyme polymorphisms accounted for tacrolimus concentration variability in kidney transplantation recipients. Furthermore, higher tacrolimus concentrations were associated with higher diarrhea and PTDM risk.

Machine learning-based method for tacrolimus dose predictions in Chinese kidney transplant perioperative patients

WHAT IS KNOWN AND OBJECTIVES

Tacrolimus (TAC), a first-line immunosuppressant in solid-organ transplant, has a narrow therapeutic window and large inter-individual variability, which affects its use in clinical practice. Successful predictions using machine learning algorithms have been reported in several fields. However, a comparison of 10 machine learning model-based TAC pharmacogenetic and pharmacokinetic dosing algorithms for kidney transplant perioperative patients of Chinese descent has not been reported. The objective of this study was to screen and establish an appropriate machine learning method to predict the individualized dosages of TAC for perioperative kidney transplant patients.

METHODS

The records of 2551 patients were collected from three transplant centres, 80% of which were randomly selected as a 'derivation cohort' to develop the dose prediction algorithm, while the remaining 20% constituted a 'validation cohort' to validate the final algorithm selected. Important features were screened according to our previously established population pharmacokinetic model of tacrolimus. The performances of the algorithms were evaluated and compared using R-squared and the mean percentage in the remaining 20% of patients.

RESULTS AND DISCUSSION

This study identified several factors influencing TAC dosage, including CYP3A5 rs776746, CYP3A4 rs4646437, haematocrit, Wuzhi capsules, TAC daily dose, age, height, weight, post-operative time, nifedipine and the medication history of the patient. According to our results, among the 10 machine learning models, the extra trees regressor (ETR) algorithm showed the best performance in the training set (R-squared: 1, mean percentage within 20%: 100%) and test set (R-squared: 0.85, mean percentage within 20%: 92.77%) of the derivation cohort. The ETR model successfully predicted the ideal TAC dosage in 97.73% of patients, especially in the intermediate dosage range (>5 mg/day to <8 mg/day), whereby the ideal TAC dosage could be successfully predicted in 99% of the patients.

WHAT IS NEW AND CONCLUSION

The results indicated that the ETR algorithm, which was chosen to establish the dose prediction model, performed better than the other nine machine learning models. This study is the first to establish ETR algorithms to predict TAC dosage. This study will further promote the individualized medication of TAC in kidney transplant patients in the future, which has great significance in ensuring the safety and effectiveness of drug use.

Effects and safety evaluation of Wuzhi Capsules combined with tacrolimus for the treatment of kidney transplantation recipients

WHAT IS KNOWN AND OBJECTIVE

Tacrolimus (FK506), an effective and potent calcineurin inhibitor, is the cornerstone of immunosuppression after kidney transplantation. Wuzhi capsule (WZC), a prescribed ethanol extract of Nan-Wuweizi (Schisandra sphenanthera), is widely prescribed for kidney transplant recipients for the maintenance of tacrolimus concentration in clinical settings. Previous studies have demonstrated that WZC can increase the blood concentration of tacrolimus. However, it remains controversial whether to use WZC can be used to increase tacrolimus concentration in clinical practice. Our study aimed to evaluate the efficacy and safety of WZC combined with tacrolimus in the treatment of kidney transplant recipients.

METHODS

One hundred and ninety four Chinese kidney transplant recipients were included in this retrospective study. The recipients were divided into two groups (non-WZC group and WZC group). We investigated the effects of WZC on tacrolimus in terms of tacrolimus metabolism, laboratory tests, pharmacogenomics, renal function and adverse reactions.

RESULTS AND DISCUSSION

The concentration/dose (C₀ /D) of tacrolimus was significantly higher in the WZC group than the non-WZC group. The laboratory findings of blood routine tests, liver and kidney function were not significantly different between the two groups. The CYP3A5 genotype showed clearly associated with tacrolimus C₀ /D, whereas no significant difference was observed in patients with CYP3A4*1B, CYP3A4*22, ABCB1, ABCC2, POR*28 or PXR alleles. The improvement of C₀ /D by administration of WZC was significant in CYP3A5 expressers compared to non-expressers. Furthermore, the WZC group had a remarkably higher proportion of subjects who reached the target tacrolimus concentration than the non-WZC group. No significant differences in renal function and adverse reactions were observed between the groups.

WHAT IS NEW AND CONCLUSION

Wuzhi capsule can increase tacrolimus concentration without negative effects on renal function and adverse reactions, especially in CYP3A5 expressers. Efficient and economical synergistic effects can be achieved by the combined administration of WZC in kidney transplant recipients.

Population pharmacokinetic analysis and dosing guidelines for tacrolimus co-administration with Wuzhi capsule in Chinese renal transplant recipients

WHAT IS KNOWN AND OBJECTIVES

Tacrolimus (TAC) is a first-line immunosuppressant which is used to prevent transplant rejection after solid organ transplantation (SOT). However, it has a narrow therapeutic index and high individual variability in pharmacokinetics (PK) and pharmacogenomics (PG). It has been reported that the metabolism of TAC can be affected by genetic factors, leading to different rates of metabolism in different subjects. Wuzhi Capsule (WZC) is a commonly used TAC-sparing agent in Chinese SOT to reduce TAC dosing due to its inhibitory effect on TAC metabolism by enzymes of the CYP3A subfamily. The aims of this study were to assess the effect of TAC+WZC co-administration and genetic polymorphism on the pharmacokinetics of TAC, by using a population pharmacokinetic (PPK) model. A dosing guideline for individualized TAC dosing is proposed based on the PPK study.

METHODS

The medical records of 165 adult patients with kidney transplant and their 824 TAC concentrations from two kidney transplantation centres were reviewed. The genotypes of four single-nucleotide polymorphisms (SNPs) in CYP3A5*3 and ABCB1 (rs1128503, rs2032582 and rs1045642) were tested by MASSARRAY. A PPK model was constructed by nonlinear mixed effect model (NONMEM^® , Version 7.3). Finally, Monte Carlo simulations were employed to design initial dosing regimens based on the final model.

RESULTS AND DISCUSSION

The one-compartmental PPK model with first-order absorption and elimination of TAC was established in kidney transplant recipients (KTRs). CYP3A5*3 had significant impact on the PPK model. The haematocrit (HCT), postoperative time (POD) and CYP3A5*3 genotypes had a significant influence on TAC clearance when combined with WZC. The model was expressed as 23.4 × (HCT/0.3)^-0.729  × 0.837 (combination with WZC) × e^{-0.0875(POD/12.6)} ×1.18 (CYP3A5 expressors). For patients carrying the CYP3A5*3/*3 allele and with 30% HCT, the required TAC dose to achieve target trough concentrations of 10-15 ng/ml was 4 mg twice daily (q12h). For patients with the CYP3A5*3/*3 allele, the required dose was 3 mg TAC q12h when combined with WZC, and for patients with the CYP3A5*1/*1 or *1/*3 allele, the required dose was 4 mg of TAC q12h when co-administered with WZC.

WHAT IS NEW AND CONCLUSION

Wuzhi Capsule co-administration and CYP3A5 variants affect the PK of TAC Dosing guidelines are made based on the PPK model to allow individualized administration of TAC, especially when co-administered with WZC.