Effects of Schisandra sphenanthera extract on the blood concentration of tacrolimus in renal transplant recipients

Exploring the effect of Wuzhi capsule on the pharmacokinetics of regorafenib and its main metabolites in rat plasma using liquid chromatography-tandem mass spectrometry

Regorafenib is a small-molecule tyrosine kinase inhibitor with severe hepatotoxicity. It undergoes metabolism mainly by CYP3A4 to generate active metabolites regorafenib-N-oxide (M2) and N-desmethyl-regorafenib-N-oxide (M5). Wuzhi capsule (WZC) is an herbal preparation derived from Schisandra sphenanthera and is potentially used to prevent regorafenib-induced hepatotoxicity. This study aims to explore the effect of WZC on the pharmacokinetics of regorafenib in rats. An efficient and sensitive liquid chromatography-tandem mass spectrometry method was developed to quantitatively determine regorafenib and its main metabolites in rat plasma. The proposed method was applied to the pharmacokinetic study of regorafenib in rats, with or without WZC. Coadministration of regorafenib with WZC resulted in a prolonged mean residence time (MRT) of the parent drug but had no statistically significant difference in other pharmacokinetic parameters. While for the main metabolites of regorafenib, WZC decreased the area under the curve and maximum concentration (Cmax ), delayed the time to reach Cmax , and prolonged the MRT of M2 and M5. These results indicate that WZC delayed and inhibited the metabolism of regorafenib to M2 and M5 by suppressing CYP3A4. Our study provides implications for the rational use of the WZC-regorafenib combination in clinical practice.

Dose-sparing effect of lapatinib co-administered with a high-fat enteral nutrition emulsion: preclinical pharmacokinetic study

Background

Lapatinib is an oral small-molecule tyrosine kinase inhibitor indicated for advanced or metastatic HER2-positive breast cancer. In order to reduce the treatment cost, a high-fat enteral nutrition emulsion TPF-T was selected as a dose-sparing agent for lapatinib-based therapies. This study aimed to investigate the effect of TPF-T on lapatinib pharmacokinetics.

Methods

First, a simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to quantitatively evaluate lapatinib in rabbit plasma. The method was fully validated according to the China Pharmacopoeia 2020 guidance. Rabbits and rats were chosen as the animal models due to their low and high bile flows, respectively. The proposed LC-MS/MS method was applied to pharmacokinetic studies of lapatinib, with or without TPF-T, in rabbit and rat plasma.

Results

The LC-MS/MS method revealed high sensitivity and excellent efficiency. In the rabbit model, co-administration with TPF-T resulted in a 32.2% increase in lapatinib exposure. In the rat model, TPF-T had minimal influence on the lapatinib exposure. In both models, TPF-T was observed to significantly elevate lapatinib concentration in the absorption phase.

Conclusion

Co-administration with TPF-T had a moderate effect on increasing exposure to lapatinib. Dose sparing using a high-fat liquid diet is potentially feasible for lapatinib-based therapies.

Interaction between Chinese medicine and digoxin: Clinical and research update

Background: Digoxin is one of the most widely and commonly used cardiac drug, which plays an irreplaceable role in treating heart failure and arrhythmia. The 2010 Edition of Pharmacopoeia of the People's Republic of China stipulates that the effective range of digoxin plasma concentration is 0.5-2.0 ng/mL and it is toxic at plasma concentration >2 ng/mL. Its effective plasma drug concentration is close to the toxic concentration, and large individual differences in the effects of the drug have been observed. It is often used in combination with other drugs, but drug interactions have a great impact on the plasma concentration of digoxin and lead to adverse reactions (ADRs), such as poisoning. Most of the reported drug interactions are with Western drugs. However, there are many combinations of traditional Chinese medicine (TCM) and Western drugs, TCM interacting with digoxin comprises monomer components, single medicines, and Chinese patent medicines. Aim of the study: We aimed i) to provide an overview of the TCM formulations affecting the pharmacology of digoxin and their mechanisms of action and ii) to provide a theoretical reference for the safe and rational use of digoxin in combination with TCM in clinical practice and to avoid ADRs. Methods: A literature search of electronic databases, including PubMed, MEDLINE, Cochrane Library, Web of Science, China National Knowledge Infrastructure, and WANFANG Data, was performed to search for articles published between 1 January 1960, and 1 August 2022. Search terms used included "digoxin," "traditional Chinese medicine," "Chinese patent medicine," and "adverse reactions" and their combinations. Results: A total of 49 articles were obtained, including clinical reports, pharmacological experiments and in vitro experiments. The mechanisms of action affecting the pharmacology of digoxin are complex. TCM formulations may affect the pharmacology of digoxin in vivo by influencing gastrointestinal motility or gastric juice pH, regulating P-glycoprotein levels, exerting cumulative pharmacological effects, and enhancing the sensitivity of the heart to digoxin. Although studies have shown that some TCM formulations interact with digoxin, they may be influenced by the complexity of the composition and the pharmacological effects of the TCM, the sensitivity of digoxin concentration determination methods, etc. The results of existing studies are controversial and further in-depth studies are required. Conclusion: Combinations of digoxin and TCM formulations are commonly used. This article serves as a reference to understand the interactions between TCM formulations and digoxin to avoid the occurrence of ADRs and improve the efficacy and safety of digoxin.

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.

Prediction of tacrolimus and Wuzhi tablet pharmacokinetic interaction magnitude in renal transplant recipients

AIM

Wuzhi tablets are a dose-sparing agent for tacrolimus (TAC) in China and increase the bioavailability of TAC. The current study aimed to evaluate the pharmacokinetic interaction magnitude of Wuzhi and TAC and explore the potential determinants of this interaction.

METHODS

This study performed a retrospective, self-controlled study of 138 renal transplant recipients who were co-administered TAC and Wuzhi. The trough concentration (C0) of TAC at baseline and 3, 7, 14 and 21 days after Wuzhi co-therapy initiation was measured, and the CYP3A5 polymorphism was genotyped. The corresponding clinical factors were recorded. The ratio of dose-adjusted C0 (C0/D) post- and pre-combination therapy (ΔC0/D) indicates the interaction magnitude. Univariate and multivariate analyses were used to identify determinants and establish the prediction model.

RESULTS

ΔC0/D reached a steady state within 14 days. The geometrical mean ΔC0/D was 2.91 (range 1.02-9.49, IQR 2.13-3.80). ΔC0/D was blunted in CYP3A5 expressers (estimated effect: -39.8%, P = .001) and affected by hematocrit (Hct) (+24.0% per 10% increase, P = .005) and baseline C0/D (-31.9% per 1 ng·ml^-1 ·mg^-1 increase, P < .001). The prediction model was ΔC0/D = .319baseline C0/D × 1.398CYP3A5 (expressers = 0/non-expressers = 1) × 1.024Hct × 1.744, and it explained 28.1% of the variability.

CONCLUSION

Our study is the first attempt to date to give an assessment of the magnitude of pharmacokinetic interaction between TAC and Wuzhi in a cohort of renal transplant recipients, and CYP3A5 genotypes, baseline C0/D and Hct were identified as determinants of this interaction.

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.

Population pharmacokinetics and dosage optimization of tacrolimus coadministration with Wuzhi capsule in adult liver transplant patients

1. This study aimed to establish a population pharmacokinetic model of tacrolimus coadministration with Wuzhi capsule and optimize the dosage regimen in adult liver transplant patients.2. Totally 1327 tacrolimus trough concentrations from 116 adult liver transplant patients were obtained for model development. A one-compartment model with first-order absorption and elimination was used to analyse the data, and the final model was internally verified using a goodness-of-fit diagnostic plot, bootstrap methods, and visual prediction test. A total of 29 patients with 250 tacrolimus trough concentrations was used for external validation via prediction-based diagnostics. Additionally, the simulation was used to optimize the recommended dose of tacrolimus and Wuzhi capsules.3. The estimated apparent clearance and volume of the distribution of tacrolimus were 15.4 L/h and 1210 L, respectively. The tacrolimus daily dose, Wuzhi capsule daily dose, postoperative time, alanine transaminase, haemoglobin, total bilirubin, direct bilirubin, estimated glomerular filtration rate, and urea, concomitant with voriconazole and fluconazole, were identified as significant covariates affecting the pharmacokinetic parameters. Internal and external validation showed that the final model was stable and reliable for predicting performance.4. The final model could provide guidance for dosage optimization of tacrolimus coadministered with Wuzhi capsules in adult liver transplantation patients.

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.

A Comprehensive Review of the Main Lignan Components of Schisandra chinensis (North Wu Wei Zi) and Schisandra sphenanthera (South Wu Wei Zi) and the Lignan-Induced Drug-Drug Interactions Based on the Inhibition of Cytochrome P450 and P-Glycoprotein Activities

Wu Wei Zi is the dried fruit of Schisandra chinensis (Turcz.) Baill. or Schisandra sphenanthera Rehd. et Wils. (family Magnoliaceae). As a homology of medicine and food, it has been widely used in China for thousands of years, to tonify the kidney, and ameliorate neurological, cardiovascular, liver, and gastrointestinal disorders. As its increasing health benefits and pharmacological value, many literatures have reported that the combination of Wu Wei Zi in patients has led to fluctuations in the blood level of the combined drug. Therefore, it is extremely important to evaluate its safety concern such as drug-drug interactions (DDIs) when patients are under the poly-therapeutic conditions. This review summarized the effects of Wu Wei Zi extract and its major lignan components on cytochrome P450 and P-glycoprotein activities, the change of which could induce metabolic DDIs. Our review also elaborated on the differences of the major lignan components of the two Schisandra species, as well as the absorption, distribution, metabolism, and elimination of the major lignans. In conclusion, these results would enhance our understanding of the DDI mechanisms involving Wu Wei Zi, and may potentially untangle some differing and conflicting results in the future.

Research Progress on the Pharmacological Action of Schisantherin A

Schisantherin A (Sch A) is a dibenzocyclooctadiene lignan monomer isolated from the fruit of Schisandra chinensis (Turcz.) Baill. (S. chinensis). At present, many studies have shown that Sch A has a wide range of pharmacological effects, including its anti-Parkinson and anti-inflammatory effects and ability to protect the liver, protect against ischemia-reperfusion (I/R) injury, suppress osteoclast formation, and improve learning and memory. Its mechanism may be related to the antioxidant, anti-inflammatory, and antiapoptotic properties of Sch A through the MAPK, NF-κB, AKT/GSK3β, and PI3K/AKT pathways. This is the first review of the recent studies on the pharmacological mechanism of Sch A.

A comprehensive review of ethnopharmacology, phytochemistry, pharmacology, and pharmacokinetics of Schisandra chinensis (Turcz.) Baill. and Schisandra sphenanthera Rehd. et Wils

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (called bei-wuweizi in Chinese, S. chinensis) and Schisandra sphenanthera (called nan-wuweizi in Chinese, S. sphenanthera) are two highly similar plants in the Magnoliaceae family. Their dried ripe fruits are commonly used as traditional Chinese medicine in the treatment of coughs, palpitation, spermatorrhea, and insomnia. They also are traditionally used as tonics in Russia, Japan, and Korea.

AIM OF THE REVIEW

S. chinensis and S. sphenanthera are similar in appearance, traditional applications, ingredient compositions, and therapeutic effects. This review, therefore, aims to provide a systematic insight into the botanical background, ethnopharmacology, phytochemistry, pharmacology, pharmacokinetics, quality control, and toxicology of S. chinensis and S. sphenanthera, and to explore and present the similarities and differences between S. chinensis and S. sphenanthera.

MATERIALS AND METHODS

A comprehensive literature search regarding S. chinensis and S. sphenanthera was collected by using electronic databases including PubMed, SciFinder, Science Direct, Web of Science, CNKI, and the online ethnobotanical database.

RESULTS

In the 2020 Edition of Chinese Pharmacopoeia (ChP), there were 100 prescriptions containing S. chinensis, while only 11 contained S. sphenanthera. Totally, 306 and 238 compounds have been isolated and identified from S. chinensis and S. sphenanthera, respectively. Among these compounds, lignans, triterpenoids, essential oils, phenolic acid, flavonoids, phytosterols are the major composition. Through investigation of pharmacological activities, S. chinensis and S. sphenanthera have similar therapeutic effects including hepatoprotection, neuroprotection, cardioprotection, anticancer, antioxidation, anti-inflammation, and hypoglycemic effect. Besides, S. chinensis turns out to have more effects including reproductive regulation and immunomodulatory, antimicrobial, antitussive and antiasthmatic, anti-fatigue, antiarthritic, and bone remodeling effects. Both S. chinensis and S. sphenanthera have inhibitory effects on CYP3A and P-gp, which can mediate metabolism or efflux of substrates, and therefore interact with many drugs.

CONCLUSIONS

S. chinensis and S. sphenanthera have great similarities. Dibenzocyclooctadiene lignans are regarded to contribute to most of the bioactivities. Schisandrin A-C, schisandrol A-B, and schisantherin A, existing in both S. chinensis and S. sphenanthera but differing in the amount, are the main active components, which may contribute to the similarities and differences. Study corresponding to the traditional use is needed to reveal the deep connotation of the use of S. chinensis and S. sphenanthera as traditional Chinese medicine. In addition, a joint study of S. chinensis and S. sphenanthera can better show the difference between them, which can provide a reference for clinical application. It is worth mentioning that the inhibition of S. chinensis and S. sphenanthera on CYP3A and P-gp may lead to undesirable drug-drug interactions.

Schisandra sphenanthera: A Comprehensive Review of its Botany, Phytochemistry, Pharmacology, and Clinical Applications

Schisandra sphenanthera Rehd. et Wils (S. sphenanthera) is a single species of Schisandra genus, Magnoliaceae family, and it is a famous medicinal herb mostly growing in southern China, China Taiwan and Vietnam. S. sphenanthera is usually used for the treatments of hepatitis, Alzheimer's disease, renal transplantation, osteoporosis, and insomnia. In present studies, approximately 310 natural constituents have been isolated from S. sphenanthera, including lignans, triterpenes, volatile oils, and polysaccharides, which were mainly obtained from the fruits and stems of S. sphenanthera. Pharmocological studies have shown that the extracts and monomeric compounds of S. sphenanthera possessed wide-range bioactivities, such as antitumor, anti-oxidant, anti-inflammatory, osteoblastic, immune regulation, neuroprotective, kidney protection, hepatoprotective, and antiviral activities. However, resource availability, quality control measures, in-depth in vivo pharmacological study, and clinical application are still insufficient and deserve further studies. This review systematically summarized literatures on the botany, phytochemistry, pharmacology, development utilization, and clinical application of S. sphenanthera, in hopes of provide a useful reference for researchers for further studies of this plant.

Wuzhi Capsule Dosage Affects Tacrolimus Elimination in Adult Kidney Transplant Recipients, as Determined by a Population Pharmacokinetics Analysis

Purpose

In this study, we aimed to establish a tacrolimus population pharmacokinetic model and better understand the drug-drug interaction between Wuzhi capsule and tacrolimus in Chinese renal transplant recipients.

Patients and Methods

We performed a population pharmacokinetic analysis using a non-linear mixed-effects model to determine the suitable Wuzhi capsule dose in combination with tacrolimus. Data on 1378 tacrolimus steady-state concentrations were obtained from 142 patients who received kidney transplant in Changhai Hospital and Huashan Hospital. Demographic characteristics, laboratory tests, genetic polymorphisms, and co-medications were evaluated.

Results

The one-compartment model best described data. Our final model identified creatinine clearance rate, hematocrit, Wuzhi capsule dose, CYP3A5*3 genetic polymorphisms, and tacrolimus daily dose as significant covariates for tacrolimus clearance, with the value of 14.4 L h^-1, and the between-subject variability (BSV) was 25.4%. The Wuzhi capsule showed a dose-dependent effect on tacrolimus pharmacokinetics, demonstrating a stronger inhibitory effect than inductive effect.

Conclusion

Our model can accurately describe population pharmacokinetics of tacrolimus when combined with different doses of Wuzhi capsule. Additionally, this model can be used for individualizing tacrolimus dose following kidney transplantation.

Effects of Postoperative Day and NR1I2 on Tacrolimus Clearance in Chinese Liver Transplant Recipients-A Population Model Approach

We aimed to explore the new biomarkers influencing tacrolimus in vivo behavior in Chinese liver transplant recipients. A total of 418 drug concentration samples of 41 liver transplant patients were collected for modeling. A population pharmacokinetic model was developed using the nonlinear mixed-effects modeling approach. The potential covariates, such as postoperative day (POD), age, body weight, hepatic and renal function, and recipient genetic polymorphisms (ABCB1, CYP3A4, CYP3A5, NR1I2) were evaluated using forward-inclusion and backward-elimination methods. A 1-compartment model was used describing the in vivo behavior of tacrolimus in liver transplant patients. The estimates of CL/F and V/F were 8.88 L/h and 495.82 L, respectively. Two covariates, POD and NR1I2 rs2276707 genotypes, were incorporated into the final population pharmacokinetic model, and they could significantly impact the CL/F: CL/F (L/h) = 8.88 × (POD/16)^0.18 × e^{0.91 × NR1I2} × e^ηCL . The model evaluation and validation indicated a stable and precise performance of the final model. The functional annotation using ENCODE data indicated that rs2276707 was located on the higher peak of the H3K4Me1 and H3K4Me3 histone marker. To our knowledge, this is the first report indicating NR1I2 rs2276707 genotypes is another biomarker impacting tacrolimus clearance in liver transplant recipients. The NR1I2 gene polymorphism may affect the in vivo behavior of tacrolimus by regulating gene expression.

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.

Co-administration of Wuzhi tablet (Schisandra sphenanthera extract) alters tacrolimus pharmacokinetics in a dose- and time-dependent manner in rats

ETHNOPHARMACOLOGY RELEVANCE

Tacrolimus is a well-known potent but expensive immunosuppressant. We previously clarified the herb-drug interaction between tacrolimus and Wuzhi tablet (WZ), a prescribed drug of ethanol extract of Schisandra sphenanthera, and showed the ideal effect of WZ on maintaining therapeutic level of tacrolimus and reducing the total drug expense. However, WZ possesses a biphasic effect on regulating CYP3A (the major metabolizing enzyme of tacrolimus), which could induce the mRNA and protein expression after long-term treatment while transiently inhibit the activity of CYP3A. In clinic, clinicians are confused about the relationship between the blood concentration of tacrolimus and the dose and the duration of pretreatment of WZ. Therefore, the effects of the pretreatment time and the dose of WZ on the pharmacokinetics of tacrolimus is urgently needed to be clarified to better combine the use of WZ and tacrolimus in clinic.

AIM OF THE STUDY AND METHOD

This study aimed to investigate the effects of the pretreatment time and the dose of WZ on the pharmacokinetics of tacrolimus in rats.

RESULTS AND CONCLUSIONS

After pretreated rats with WZ for 0, 0.5, 2, 6, 12 or 24 h, the area under the curve (AUC) of tacrolimus was 2.27 ± 0.59, 1.87 ± 1.14, 2.86 ± 0.64, 1.62 ± 0.70, 1.54 ± 1.06 and 1.12 ± 0.69-fold of that of the tacrolimus alone group, respectively. The ratio of AUC of tacrolimus to that of the co-administration group with 0, 62.5, 125, 250, 500 or 750 mg/kg of WZ was 1.00: 1.07: 1.44: 2.60: 2.32: 2.42, respectively. These findings suggested that WZ increased tacrolimus AUC in a pretreatment time- and dose-dependent manner. In line with the in vivo findings, WZ extract inhibited CYP3A activity in a pre-treatment time- and concentration-dependent manner in human liver microsomes. In conclusion, the pharmacokinetics of tacrolimus was significantly affected by the pretreatment time and the dose of WZ. Oral pretreatment with WZ for 0-2 h or co-dosing of 250 mg/kg of WZ most significantly increased the blood concentration of tacrolimus. These findings would be helpful for guiding the reasonable use of WZ and tacrolimus in clinic.

Population pharmacokinetics and pharmacogenomics of tacrolimus in Chinese children receiving a liver transplant: initial dose recommendation

BACKGROUND

In order to improve the precision of treatment with tacrolimus in Chinese patients undergoing pediatric liver transplantation, the optimum initial dose of tacrolimus was determined based on population pharmacokinetics and pharmacogenomics.

METHODS

Demographic data, clinical parameters, drug combinations and pharmacogenomics were integrated to build a population pharmacokinetic model using NONMEM. Additionally, Monte Carlo simulations were used to optimize the recommended initial dose.

RESULTS

Weight, patient cytochrome 450 3A (CYP3A)5 genotype, and co-administration with wuzhi-capsule (WZ) were incorporated into the final model. For children with a CYP3A5*3/*3 genotype not co-administered WZ, 0.10 mg/kg/day split into two doses was recommended for patients weighing 5-17 kg, and 0.05 mg/kg/day split into two doses was recommended for patients weighing 17-60 kg. For children with a CYP3A5*1 allele not co-administered WZ, 0.25 mg/kg/day for patients weighing 5-10 kg, 0.20 mg/kg/day for patients weighing 10-17 kg, 0.15 mg/kg/day for patients weighing 17-36 kg, and 0.10 mg/kg/day for patients weighing 36-60 kg; all split into two doses was recommended. For children with a CYP3A5*3/*3 genotype co-administered WZ, 0.10 mg/kg/day for patients weighing 5-11 kg, and 0.05 mg/kg/day for patients weighing 11-60 kg; both split into two doses was recommended. For children with a CYP3A5*1 allele who were co-administered WZ, 0.20 mg/kg/day for patients weighing 5-10 kg, 0.15 mg/kg/day for patients weighing 10-22 kg, and 0.10 mg/kg/day for patients weighing 22-60 kg all split into two doses was recommended.

CONCLUSIONS

The optimal initial dose of tacrolimus was determined based on population pharmacokinetics and pharmacogenomics in Chinese patients undergoing pediatric liver transplantation.

Population pharmacokinetics model and initial dose optimization of tacrolimus in children and adolescents with lupus nephritis based on real-world data

The present study aimed to establish a population pharmacokinetics model of tacrolimus and further optimize the initial dosing regimen of tacrolimus in pediatric and adolescent patients with lupus nephritis (LN). Pediatric and adolescent patients with LN were recruited between August 2014 and September 2019 at the Children's Hospital of Fudan University (Shanghai, China). Relevant information was used to set up a population pharmacokinetics model with a Nonlinear Mixed Effect Model and the initial dosage regimen was simulated with the Monte Carlo method. Body weight and co-administration of wuzhi capsule were indicated to influence tacrolimus clearance in pediatric and adolescent patients with LN, and at the same body weight, the rate of tacrolimus clearance in patients without vs. with co-administration of wuzhi capsule was 1:0.71. In addition, in patients who were not administered wuzhi capsule, an initial dosage regimen of 0.15 mg/kg/day was recommended for a body weight of 10-23 kg and 0.10 mg/kg/day for 23-60 kg; in patients who were administered wuzhi capsule, an initial dosage regimen of 0.10 mg/kg/day was recommended for a body weight of 10-23 kg and 0.05 mg/kg/day for 23-60 kg. To the best of our knowledge, the present study was the first to establish a population pharmacokinetics model of tacrolimus in order to determine the optimal initial dosage regimen of tacrolimus in pediatric and adolescent patients with LN.

Clinical observation on the effect of Wuzhi soft capsule on FK506 concentration in membranous nephropathy patients

The current research aimed to investigate the correlation between the effect of Wuzhi soft capsule (WZC) on FK506 concentration and CYP3A5 gene polymorphism in patients with membranous nephropathy (MN).Seventy-five patients with idiopathic MN were enrolled and divided according to the expression of CYP3A5 gene metabolic enzyme into group A (CP3A5 metabolic enzyme function expression types CYP3A5*1/*1 type and CYP3A5*1/*3 type), and group B (non-expression type CYP3A5*3/*3 type). All patients were given oral administration of tacrolimus capsule at the initial dose of 1 mg for twice a day 1 hour before breakfast and dinner. Afterwards, the oral administration of WZC was added at the dose of 0.5 g for 3 times a day within half an hour after 3 meals.The blood concentrations of FK506 in groups A and B were significantly higher than those before administration. Compared with that before administration, the FK506 blood concentration was increased by 3.051 ± 0.774 ng/ml after adding the WZC. Besides, the blood concentrations of FK506 in group A were lower than those in group B before and after administration; meanwhile, the 24 hours total urine protein and the biochemical indexes in both groups displayed no statistically significant difference. Only 1 case of diarrhea was observed, which was relieved after the reduction of tacrolimus.Wuzhi soft capsule can significantly increase the blood concentration of FK506 in MN patients. Moreover, the CYP3A5 genotyping should be considered when WZC is used to increase the blood concentration of FK506.

The Pharmacokinetic Prediction of Cyclosporin A after Coadministration with Wuzhi Capsule

We aim to describe the influence of principal ingredients of Wuzhi capsule, schisandrin A (SIA) and schisantherin A (STA), on the pharmacokinetics of cyclosporin A (CsA) and to quantify the herb-drug interactions (HDIs) between SIA, STA, and CsA. CsA is a first-line immunosuppressant for anti-rejection therapy after solid organ transplantation, while narrow therapeutic window associated with strong hepatotoxicity largely limited its use. Wuzhi capsule, a liver-protective drug, was approved for coadministration with CsA to reduce the hepatotoxicity. There are few studies exploring HDIs of CsA when coadministered with Wuzhi capsule. The essential adjusted physicochemical data and pharmacokinetic parameters of SIA, STA, and CsA were collected. Then physiologically based pharmacokinetic (PBPK) models of SIA, STA, and CsA were built and verified in healthy subjects using Simcyp respectively. The refined PBPK models were used to estimate potential HDIs between CsA and SIA, STA. The simulated plasma concentration-time curves of CsA, SIA, and STA were in good accordance with the observed profiles respectively. CsA pharmacokinetics were improved after coadministration. After a single dose and multiple doses, the area under the plasma concentration-time curve (AUC) of CsA was increased by 47% and 226% when coadministered with STA, respectively, and by 8% and 36% when coadministered with SIA, respectively. PBPK models sufficiently described the pharmacokinetics of CsA, SIA, and STA. Compared with SIA, STA inhibited CsA metabolism to a greater extent. Our result revealed the dose of CsA can be reduced to maintain similar profile when used concomitantly with Wuzhi capsule.

Model extrapolation to a real-world dataset: evaluation of tacrolimus population pharmacokinetics and drug interaction in pediatric liver transplantation patients

1. Numerous tacrolimus population pharmacokinetic (PPK) models in pediatric liver transplantation patients have been established to define an optimal dose schedule. However, the applicability of extrapolating these PPK models to our clinical center remains unknown. The goals of the present study was to evaluate model external predictiveness and establish a new model applicable to traditional therapeutic drug monitoring data.2. Published PPK models were collected from the literature and assessed using our real-world dataset including 41 pediatric liver transplantation patients via the individual prediction error method. The establishment of a new model was characterized using non-linear mixed-effects modeling.3. Nine published pediatric liver transplantation PPK models were identified, three of which could be applied to our real-world dataset. However, these models were dissatisfactory in terms of individual prediction error and hence, inadequate for extrapolation. Finally, a new model applicable to our real-world dataset was established as follows: CL/F = 22.9 × (WT/70)^0.75 × (1 - WZ × 0.264) × (1 - FCZ × 0.338) × (1 + ASPI × 0.281) × (POD/41)^0.0486 L/h; V/F = 906 × (WT/70) L. Where WT, WZ, FCZ, ASPI and POD were weight, Wuzhi capsule, fluconazole, aspirin and post-transplantation day, respectively. In conclusion, published models were inadequate for application to our real-world dataset. The present study produced a new model applicable to our real-world study data.

The impact of azole antifungal drugs on imatinib metabolism in human liver microsomes

1. Imatinib is widely used for the treatment of hematologic malignancies. It is common that imatinib is clinically co-prescribed with azole antifungal agents since these patients are more prone to invasive antifungal infection. The present study was to investigate the effects of azole antifungal drugs, including ketoconazole, fluconazole, voriconazole, itraconazole and posaconazole on imatinib metabolism. 2. The main metabolites, 1-OH midazolam and N-desmethyl imatinib, were determined in the absence and in the presence of various levels of ketoconazole, fluconazole, voriconazole, itraconazole and posaconazole. The relevant assay was also performed to screen mechanism-based inhibitors (MBI). 3.   The inhibition ability of 1-OH midazolam formation from midazolam based on IC₅₀ values was ketoconazole (0.09 µM)>itraconazole (0.31 µM)> posaconazole (0.68 µM)>voriconazole (2.10 µM) > fluconazole (8.90 µM). Similarly, the rank order of inhibitory effects on formation of N-desmethyl imatinib from imatinib was ketoconazole (4.58 µM)>itraconazole (17.45 µM)> posaconazole (31.02 µM)> voriconazole (367.9 µM) >fluconazole (1.11 mM). Posaconazole and itraconazole displayed evidence of MBI. Additionally, imatinib was also shown as a MBI of CYP3A with IC₅₀ value of 5.40 µM against the midazolam. 4. The significant difference in IC₅₀ values of midazolam and imatinib inhibited by azole antifungal agents was observed. The role of CYP2C8 in imatinib metabolism and imatinib autoinhibits CYP3A activity may explain this difference. Our findings suggest that the azole antifungal agents might have limited impacts on imatinib exposure by CYP3A activity.

Population pharmacokinetic analysis of tacrolimus in Chinese cardiac transplant recipients

Objective

Usage of tacrolimus is complicated by its narrow therapeutic index and wide between- and within-subject pharmacokinetic variability. We aimed to obtain more information regarding the influence of various covariates on the disposition of tacrolimus in the early phase after cardiac transplantation using a population pharmacokinetic method, and provide information for the individualisation of drug dosing in the clinical setting.

Methods

Routine therapeutic drug monitoring concentrations (897 observations) were retrospectively collected from 146 hospitalised patients. One compartment model with first-order absorption (absorption rate constant K_a was fixed as 4.48/hour) was employed to establish the population pharmacokinetic model using a non-linear mixed-effects modelling approach. Various demographic parameters, postoperative day and concomitant medications influencing drug clearance and distribution volume were investigated in this study. Bootstrap and prediction-corrected visual predictive check were employed to validate the final model. With the goal of tacrolimus trough concentrations within the therapeutic window, simulation was performed.

Results

Pharmacokinetic parameter population typical estimates for clearance (CL/F) and apparent distribution volume (V/F) were 14.23 L/hour and 760.80 L, respectively. Postoperative day and co-administration of Wuzhi capsules were identified as important factors affecting CL/F. Total body weight was significantly associated with the V/F. Results of model evaluation indicated a good stable and precise performance of the final model. Based on the simulation results, a simple-touse dosage regimen table to guide clinicians with drug dosing was created.

Conclusion

The final population model could provide information for the individualised dosing of tacrolimus for cardiac transplant recipients.

Prediction of tacrolimus dosage in the early period after heart transplantation: a population pharmacokinetic approach

Aim: The aim of this study was to evaluate tacrolimus population pharmacokinetics and investigate factors that explain tacrolimus variability in adult heart transplant patients. Methods: A total of 707 tacrolimus concentrations from 107 adult heart transplant patients were included in model development. The effects of demographic, clinical factors and CYP3A5 genotype on tacrolimus clearance were evaluated using a nonlinear mixed-effects modeling. 24 patients with 106 tacrolimus concentrations were used for external validation. Results: The pharmacokinetic data were adequately described by a one-compartment model with first-order absorption and elimination. The estimated apparent clearance and volume of distribution of tacrolimus were 13.7 l/h and 791 l, respectively. Tacrolimus apparent clearance was significantly reduced in CYP3A5 nonexpressers (CYP3A5*3/*3), concomitant with azole antifungal drugs and Wuzhi capsule (WZ). A predictive performance was further confirmed in an external validation by Bayesian estimation. Recommended dose regimens were obtained by simulations based on the established model. Conclusion: This is the first population pharmacokinetic study conducted in Chinese heart transplant recipients. These findings are of great importance with regards to tacrolimus dose optimization in heart transplantation patients.

Prediction of Drug-Drug Interaction between Tacrolimus and Principal Ingredients of Wuzhi Capsule in Chinese Healthy Volunteers Using Physiologically-Based Pharmacokinetic Modelling

Schisantherin A and schisandrin A, the most abundant active ingredients of Wuzhi capsule, are known to inhibit tacrolimus metabolism by inhibiting CYP3A4/5. We aimed to predict the contribution of schisantherin A and schisandrin A to drug-drug interaction (DDI) between Wuzhi capsule and tacrolimus using physiologically-based pharmacokinetic (PBPK) modelling. Firstly, the inhibition mechanism of schisantherin A and schisandrin A on CYP3A4/5 was investigated. Thereafter, PBPK models of schisantherin A, schisandrin A and tacrolimus were established. Finally, tacrolimus pharmacokinetics were evaluated after the combined use with schisantherin A or schisandrin A. The blood area under the curve (AUC) of tacrolimus increased 1.77- and 2.61-fold after a single dose and multiple doses of schisantherin A, respectively. Meanwhile, schisandrin A inhibited tacrolimus metabolism to a smaller extent. Also, it showed that mechanism-based inhibition (MBI) played a more important role in DDI than reversible inhibition after long-term administration, while reversible inhibition was comparable to MBI after single-dose administration. In conclusion, we utilized PBPK modelling to quantify the contribution of schisantherin A and schisandrin A to DDI between tacrolimus and Wuzhi capsule. This may provide more insights for the rational use of this drug combination.

Tacrolimus in preventing transplant rejection in Chinese patients--optimizing use

Tacrolimus is a product of fermentation of Streptomyces, and belongs to the family of calcineurin inhibitors. It is a widely used immunosuppressive drug for preventing solid-organ transplant rejection. Compared to cyclosporine, tacrolimus has greater immunosuppressive potency and a lower incidence of side effects. It has been accepted as first-line treatment after liver and kidney transplantation. Tacrolimus has specific features in Chinese transplant patients; its in vivo pharmacokinetics, treatment regimen, dose and administration, and adverse-effect profile are influenced by multiple factors, such as genetics and the spectrum of primary diseases in the Chinese population. We reviewed the clinical experience of tacrolimus use in Chinese liver- and kidney-transplant patients, including the pharmacology of tacrolimus, the immunosuppressive effects of tacrolimus versus cyclosporine, effects of different factors on tacrolimus metabolism on Chinese patients, personalized medicine, clinical safety profile, and patient satisfaction and adherence. This article provides guidance for the rational and efficient use of tacrolimus in Chinese organ-transplant patients.

Effect of Tacrolimus on the pharmacokinetics of bioactive lignans of Wuzhi tablet (Schisandra sphenanthera extract) and the potential roles of CYP3A and P-gp

We recently reported that Wuzhi tablet (WZ), a preparation of the ethanol extract of Wuweizi (Schisandra sphenanthera), had significant effects on blood concentrations of Tacrolimus (FK506) in renal transplant recipients and rats. The active lignans in WZ are schisandrin A, schisandrin B, schisandrin C, schisandrol A, schisandrol B, schisantherin A, and schisantherin B. Until now, whether the pharmacokinetics of these lignans in WZ would be affected by FK506 remained unknown. Therefore, this study aimed to investigate whether and how FK506 affected pharmacokinetics of lignans in WZ in rats and the potential roles of CYP3A and P-gp. After a single oral co-administration of FK506 and WZ, the blood concentration of lignans in WZ was decreased by FK506; furthermore, the AUC of schisantherin A, schisandrin A, schisandrol A and schisandrol B was only 64.5%, 47.2%, 55.1% and 57.4% of that of WZ alone group, respectively. Transport study in Caco-2 cells showed that these lignans were not substrates of P-gp, suggesting decreased blood concentration of lignans by FK506 was not via P-gp pathway. Metabolism study in the human recombinant CYP 3A showed that these lignans had higher affinity to CYP3A than that of FK506, and thus had a stronger CYP3A-mediated metabolism. It was concluded that the blood concentrations of these lignans were decreased and their CYP3A-mediated metabolisms were increased in the presence of FK506 since these lignans had higher affinity to CYP3A.

From gut to kidney: transporting and metabolizing calcineurin-inhibitors in solid organ transplantation

Since their introduction circa 35 years ago, calcineurin-inhibitors (CNI) have become the cornerstone of immunosuppressive therapy in solid organ transplantation. However, CNI's possess a narrow therapeutic index with potential severe consequences of drug under- or overexposure. This demands a meticulous policy of Therapeutic Drug Monitoring (TDM) to optimize outcome. In clinical practice optimal dosing is difficult to achieve due to important inter- and intraindividual variation in CNI pharmacokinetics. A complex and often interdependent set of factors appears relevant in determining drug exposure. These include recipient characteristics such as age, race, body composition, organ function, and food intake, but also graft-related characteristics such as: size, donor-age, and time after transplantation can be important. Fundamental (in vitro) and clinical studies have pointed out the intrinsic relation between the aforementioned variables and the functional capacity of enzymes and transporters involved in CNI metabolism, primarily located in intestine, liver and kidney. Commonly occurring polymorphisms in genes responsible for CNI metabolism (CYP3A4, CYP3A5, CYP3A7, PXR, POR, ABCB1 (P-gp) and possibly UGT) are able to explain an important part of interindividual variability. In particular, a highly prevalent SNP in CYP3A5 has proven to be an important determinant of CNI dose requirements and drug-dose-interactions. In addition, a discrepancy in genotype between graft and receptor has to be taken into account. Furthermore, common phenomena in solid organ transplantation such as inflammation, ischemia- reperfusion injury, graft function, co-medication, altered food intake and intestinal motility can have a differential effect on the expression enzymes and transporters involved in CNI metabolism. Notwithstanding the built-up knowledge, predicting individual CNI pharmacokinetics and dose requirements on the basis of current clinical and experimental data remains a challenge.