Xiao-cong Zuo

Effects of CYP3A4 and CYP3A5 polymorphisms on tacrolimus pharmacokinetics in Chinese adult renal transplant recipients: a population pharmacokinetic analysis.

Objective Tacrolimus is used clinically for the long-term treatment of antirejection of transplanted organs in liver and kidney transplant recipients, although dose optimization is poorly managed. The aim of this study was to examine the association between tacrolimus pharmacokinetic variability and CYP3A4 and CYP3A5 genotypes by a population pharmacokinetic analysis based on routine drug monitoring data in adult renal transplant recipients. Materials and methods Trough tacrolimus concentrations were obtained from 161 adult kidney transplant recipients after transplantation. The population pharmacokinetic analysis was carried out using the nonlinear mixed-effect modeling software NONMEM version 7.2. The CYP3A4*1G and CYP3A5*3 genetic polymorphisms from the patients studied were determined by direct sequencing using a validated automated genetic analyzer. Results A one-compartment model with first-order absorption and elimination adequately described the pharmacokinetics of tacrolimus. Covariates including CYP3A5*3 and CYP3A4*1G alleles and hematocrit were retained in the final model. The apparent clearance of tacrolimus was about two-fold higher in kidney transplant patients with higher enzymatic activity of CYP3A5*1 and CYP3A4*1G (with the CYP3A5*1/*1 or *1/*3 and CYP3A4*1/*1G or CYP3A4*1G/*1G) compared with those with lower enzymatic activity (CYP3A5*3/*3 and CYP3A4*1/*1). Conclusion This is the first study to extensively determine the effect of CYP3A4*1G and CYP3A5*3 genetic polymorphisms and hematocrit value on tacrolimus pharmacokinetics in Chinese renal transplant recipients. The findings suggest that CYP3A5*3 and CYP3A4*1G polymorphisms and hematocrit are determinant factors in the apparent clearance of tacrolimus. The initial dose design is mainly based on CYP3A5 and CYP3A4 genotypes as well as hematocrit. This result may also be useful for maintenance tacrolimus dose optimization and may help to avoid fluctuating tacrolimus levels and improve the efficacy and tolerability of tacrolimus in kidney transplant recipients.

Development and validation of an LC-MS/MS method for the determination of tolvaptan in human plasma and its application to a pharmacokinetic study.

Tolvaptan is a selective vasopressin V(2)-receptor antagonist mainly used for the treatment of hyponatremia. This study described the development and validation of an LC-MS/MS method for the determination of tolvaptan in human plasma. Sample preparation involved protein precipitation with acetonitrile containing 2-demethyl tolvaptan (internal standard, IS). Chromatographic separation was performed on a Zorbax XDB C(18) column with an isocratic mobile phase consisting of water (containing 0.1% formic acid) and methanol (25:75, v/v). Determination of the analytes was achieved by tandem-mass spectrometry with positive electrospray ionization. The multiple reaction monitoring (MRM) transitions were performed at m/z 449.2→252.1 for tolvaptan and m/z 435.2→238.1 for IS. The assay was linear over the concentration range of 0.457-1000ng/mL, with a lower limit of quantification of 0.457ng/mL. The intra- and inter-day precisions at three concentration levels (0.914, 111 and 800ng/mL) were less than 15% and their accuracies were within the range of 97.7-107.8%. The mean recovery ranged from 99.2 to 104.6% and the matrix effect from 89.3 to 99.5%. Tolvaptan was stable under all tested conditions. This validated method was successfully applied to a pharmacokinetic study in healthy volunteers after oral administration of single-dose tolvaptan tablets.

A meta‐analysis comparing the efficacy of entecavir and tenofovir for the treatment of chronic hepatitis B infection

The efficacy of entecavir and tenofovir in patients with chronic hepatitis B virus (HBV) is inconsistent. To address this issue, we conducted a meta‐analysis based on a current review of the literature addressing the efficacy and safety of entecavir and tenofovir. Electronic databases were searched through June 2014 for relevant clinical trials. We included 2 randomized controlled trials, 2 prospective cohort studies, and 7 case‐control studies that included 1,656 patients. In the entecavir group, 842 of 992 were nucleos(t)ide‐naïve chronic HBV patients, and in the tenofovir group 481 of 664 were nucleos(t)ide‐naïve. The virological response to tenofovir was superior to entecavir (RR: 0.82; 95%CI: 0.72–0.93), especially in nucleos(t)ide‐naïve chronic HBV patients at 48 weeks (RR: 0.78; 95%CI: 0.65–0.92). Additionally, there was no difference between entecavir and tenofovir for virological response at 24 weeks (RR: 0.87, 95%CI: 0.71–1.05). The alanine aminotransferase normalization rate, serological response, and adverse event rate were also not significantly different between entecavir and tenofovir at 24 or 48 weeks after treatment. These results suggest that tenofovir is a better choice to treat chronic HBV patients than entecavir as it is better able to suppress HBV viral load and has a similar safety profile.

Tacrolimus decreases insulin sensitivity without reducing fasting insulin concentration: a 2-year follow-up study in kidney transplant recipients.

Abstract New Onset Diabetes after Transplantation (NODAT) is defined as sustained hyperglycemia developing in patients without diabetes history before transplantation. A cohort study was performed to access the effects of tacrolimus on insulin secretion and insulin sensitivity and consequently in the development of NODAT in kidney transplant recipients. Then, we further investigated the association between NODAT and single-nucleotide polymorphisms of IRS-1 and IRS-2 in renal allograft recipients. One hundred and fifty-eight kidney transplant patients, receiving tacrolimus as the base immunosuppressant, were divided into two groups: with or without NODAT. Plasma levels of fasting insulin concentration (FINS) and C-peptide were determined by enhanced chemiluminescence immunoassay and ADVIA Centaur C peptide assay, respectively. The genotypes of Gly1057Asp in IRS-2 and Gly972Arg in IRS-1 were detected through polymerase chain reaction fragment length polymorphism in NODAT and non-NODAT patients. It was found that the concentrations of fasting plasma insulin and C-peptide in NODAT and non-NODAT patients treated with tacrolimus were higher than that in healthy volunteers (p < 0.05). Fasting plasma insulin concentration in NODAT was significantly elevated compared with than that in non-NODAT group (p < 0.05). But there are no statistical differences in fasting plasma C-peptide concentrations between NODAT and non-NODAT groups. The allele and genotype frequencies of IRS-2 Gly1057Asp and IRS-1 Gly972Arg in NODAT patients were not significantly different from non-NODAT patients (p > 0.05). In conclusion, insulin resistance is the primary cause of tacrolimus-induced NODAT. The IRS-2 Gly1057Asp and IRS-1 Gly972Arg genotypes are not related to NODAT.

Comparing Antihypertensive Effect and Plasma Ciclosporin Concentration between Amlodipine and Valsartan Regimens in Hypertensive Renal Transplant Patients Receiving Ciclosporin Therapy

BackgroundHypertension, a major complication in kidney transplant recipients, is associated with premature death and graft loss. However, an optimal antihypertensive therapy for these patients has not been established [Chinese Clinical Trial Registry No. ChiCTR-TRC-10001071].ObjectiveThe aim of the present study was to evaluate the effect of amlodipine and valsartan on BP control in renal transplant patients and to analyze the correlation between cytochrome P450 (CYP) 3A5 or multidrug resistance-1 gene (MDR1) genotype and the antihypertensive effect of these two regimens.Methods150 renal transplant patients with stage 1 or 2 hypertension were enrolled in the trial. Patients were randomly assigned to amlodipine or valsartan. Metoprolol was added if BP was not under control after 4 weeks. BP and plasma levels of ciclosporin were monitored during the 24-week trial. CYP3A5 and MDR1 genotypes were determined using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.ResultsThe demographic features and baseline BP were similar between these two groups. During the 24-week trial, the reduction of systolic BP (SBP) was similar between the amlodipine and valsartan groups. However, the reduction of diastolic BP (DBP) was significantly greater in the amlodipine group compared with the valsartan group at 12, 16, and 24 weeks of treatment. The plasma level of ciclosporin at 2 hours of medication was significantly higher in the amlodipine group than in the valsartan group after 4 weeks of the trial. The reduction of DBP at 24 weeks was greater in the subjects with CYP3A5 *3/*3 variant than in those with CYP3A5*1/*1 variant (−13.5± 1.9mmHg vs −8.7± 1.6mmHg, p<0.05).ConclusionThe present study demonstrated that amlodipine produced a greater reduction of DBP than valsartan, although both amlodipine and valsartan resulted in satisfactory control of BP in patients with renal transplantation. Administration of amlodipine significantly increased the plasma concentration of ciclosporin, and its effects on BP control and ciclosporin concentration may be associated with the CYP3A5 genotype in these subjects [Chinese Clinical Trial Registry No. ChiCTR-TRC-10001071].

Effect of amlodipine on the pharmacokinetics of tacrolimus in rats.

Abstract 1. The immunosuppressant tacrolimus (TAC) is a substrate of cytochrome P450 3A2 (CYP3A2) and P-glycoprotein (P-gp) in rats. Amlodipine (AML) is an inhibitor of CYP3A2 in rats. We investigated the effect of AML on the pharmacokinetics of TAC in rats. 2. When co-administered with TAC orally or intravenously, AML decreased the oral clearance and raised the blood concentration of TAC in rats, but the T1/2 of TAC was not significantly affected by AML. Upon oral administration of TAC, the effect of 15 mg/kg of AML on the AUC of TAC was lower than that seen with 5 or 10 mg/kg. However, upon intravenous TAC administration, the effect of 15 mg/kg of AML on the AUC of TAC was higher than that seen with 5 mg/kg. 3. AML is an inhibitor of P-gp and CYP3A2 in rats. If AML and TAC are co-administered orally, AML elicits greater inhibition in P-gp than CYP3A2 during first-pass metabolism. If AML is given orally and TAC given intravenously concurrently, AML mainly inhibits CYP3A2 activity and increases the blood concentration of TAC. There are significant pharmacokinetic interactions between TAC and AML. AML raises the blood concentration of TAC in rats probably by inhibiting P-gp and CYP3A2.

Preprocedural Prediction Model for Contrast‐Induced Nephropathy Patients

Background Several models have been developed for prediction of contrast‐induced nephropathy (CIN); however, they only contain patients receiving intra‐arterial contrast media for coronary angiographic procedures, which represent a small proportion of all contrast procedures. In addition, most of them evaluate radiological interventional procedure‐related variables. So it is necessary for us to develop a model for prediction of CIN before radiological procedures among patients administered contrast media. Methods and Results A total of 8800 patients undergoing contrast administration were randomly assigned in a 4:1 ratio to development and validation data sets. CIN was defined as an increase of 25% and/or 0.5 mg/dL in serum creatinine within 72 hours above the baseline value. Preprocedural clinical variables were used to develop the prediction model from the training data set by the machine learning method of random forest, and 5‐fold cross‐validation was used to evaluate the prediction accuracies of the model. Finally we tested this model in the validation data set. The incidence of CIN was 13.38%. We built a prediction model with 13 preprocedural variables selected from 83 variables. The model obtained an area under the receiver‐operating characteristic (ROC) curve (AUC) of 0.907 and gave prediction accuracy of 80.8%, sensitivity of 82.7%, specificity of 78.8%, and Matthews correlation coefficient of 61.5%. For the first time, 3 new factors are included in the model: the decreased sodium concentration, the INR value, and the preprocedural glucose level. Conclusions The newly established model shows excellent predictive ability of CIN development and thereby provides preventative measures for CIN.

Contrast Media-Induced Renal Inflammation Is Mediated Through HMGB1 and Its Receptors in Human Tubular Cells

With the rapid development of imaging diagnosis and interventional therapy, contrast media (CM) are widely used in clinics. However, contrast-induced nephropathy (CIN) is the third leading cause of hospital-acquired acute renal failure accounting for 10-12% of all causes of hospital-acquired renal failure. Recent study found that inflammation may participate in the pathogenesis of CIN, but the role of it remains unclear. HK-2 cells were treated with Iohexol, Urografin, and mannitol. Two types of CM increased the release of HMGB1 in cell supernatant accompanied by increased expression of TLR2 and CXCR4. Iohexol and Urografin also caused a significant increase in NF-κB followed by the release of IL-6 and MCP-1. To clarify the role of HMGB1, TLR2, and CXCR4, glycyrrhizin, anti-TLR2-IgG, and AMD3100 were used to inhibit HMGB1, TLR2, and CXCR4, respectively. Significant decrease in the expression of TLR2, CXCR4, nuclear NF-κB, and the release of IL-6 and MCP-1 were observed. These results indicate that TLR2 and CXCR4 signaling are involved in CM-induced HK-2 cell injury model in an HMGB1-dependent pathway, which may provide a new target for the prevention and the treatment of CIN.

The Impact of Blood Pressure on Kidney Function in the Elderly: A Cross-Sectional Study

Background/Aims: Intensive blood pressure (BP) target decreases blood perfusion of kidneys that attenuates the benefits of BP treatment in elderly hypertensive individuals. The optimal BP goal for renal function in the hypertensive elderly has been unclear. We investigated the impact of BP on renal function to define the appropriate BP target in the elderly. Methods: A total of 28,258 elderly subjects were categorized into normotensive (Norm), hypotensive (Hypo) and hypertensive (Hyper) groups according to BP levels. Systolic, diastolic and pulse BP (SBP, DBP and PBP) were further stratified by 10 mmHg. Blood urea nitrogen, serum creatinine, uric acid, glomerular filtration rate (GFR), renal insufficiency prevalence (RIP) and proteinuria prevalence (PP) were compared among different groups and BP strata. The RIP and PP in the elderly with obesity, hyperlipidemia or diabetes in Norm, Hypo and Hyper groups were evaluated. Results: GFR in Hypo and Hyper groups was significantly lower than that in Norm group. The RIP and PP was higher in Hypo and Hyper groups than that in the Norm group. Proteinuria became more prevalent when SBP was >140 mmHg or <90 mmHg. DBP>80mmHg increased PP while DBP<70 mmHg increased RIP. PBP>60 mmHg led to an increased RIP and PP. Obesity or hyperlipidemia only combined with hypertension caused a significantly increased RIP and PP. Diabetes independent of hypertension contributed to higher RIP and PP. Conclusions: The most beneficial BP target for kidney function in the elderly may be SBP of 90-140 mmHg and DBP of 70-80 mmHg. PBP <60 mmHg may be appropriate.

Significant impacts of CYP3A4*1G and CYP3A5*3 genetic polymorphisms on the pharmacokinetics of diltiazem and its main metabolites in Chinese adult kidney transplant patients

The calcium channel blocker diltiazem has been used widely as a cyclosporine (CsA)/tacrolimus‐sparing agent. However, considerable interpatient variability in diltiazems CsA/tacrolimus‐sparing effect has been observed in many clinical studies. This study was carried out to investigate the impacts of the CYP3A4*1G and CYP3A5*3 genetic polymorphisms on the trough concentration/dose ratios and pharmacokinetics of diltiazem and its main metabolites in Chinese adult renal transplant patients.