Mingkang Zhong

Association of MDR1, CYP3A4*18B, and CYP3A5*3 polymorphisms with cyclosporine pharmacokinetics in Chinese renal transplant recipients

ObjectiveThe objective of this study was to retrospectively evaluate the effects of MDR1, CYP3A4*18B, and CYP3A5*3 genetic polymorphisms on cyclosporine A (CsA) pharmacokinetics in Chinese renal transplant patients during the first month after transplantation.MethodsA total of 103 renal transplant recipients receiving CsA were genotyped for MDR1 (C1236T, G2677T/A, and C3435T), CYP3A4*18B, and CYP3A5*3. The predose and 2-h postdose concentrations of CsA (C0 and C2, respectively) were determined by fluorescence polarization immunoassay, and their relationships with corresponding genotypes and haplotypes were investigated.ResultsPatients with a CYP3A4*1/*1 genotype were found to have a higher dose-adjusted concentration compared with those with CYP3A4*18B/*18B, as follows: for C2, 19.3% (P = 0.008) during days 8-15, 35.2% (P = 0.008) during days 16–30, and for C0, 39.7% (P = 0.012) during days 16–30. The dose-adjusted C0 was higher in patients with MDR1 1236CC compared with those with 1236TT in the first month postoperation. The dose-adjusted C0 in patients with the CYP3A5*3/*3 genotype was 25.5% and 30.7% higher than those with the wild-type genotype during days 8–15 (P = 0.011) and days 16–30 (P = 0.015), respectively. Haplotype analysis revealed that the dose-adjusted C0 was higher in the first month following surgery in carriers of haplotype MDR1 CAC than in noncarriers. Polymorphisms of MDR1 and CYP3A5*3 did not affect dose-adjusted C2.ConclusionThe data suggests that the CYP3A4*18B genotype affects CsA pharmacokinetics during the first month following surgery in Chinese renal transplant recipients. Patients with CYP3A4*18B alleles may require higher doses of CsA to reach the target levels. Large prospective studies may be needed to further explore the impact of MDR1 and CYP3A5*3 polymorphisms on CsA pharmacokinetics in renal transplant recipients.

Simultaneous determination of procaine, lidocaine, ropivacaine, tetracaine and bupivacaine in human plasma by high-performance liquid chromatography

A simple and sensitive high-performance liquid chromatography with ultraviolet detection (HPLC-UV) method has been developed and validated for simultaneous quantification of five local anesthetics in human plasma: procaine, lidocaine, ropivacaine, tetracaine and bupivacaine. In an ice-water bath, 500 microL plasma sample, containing 100 microg/mL neostigmine methylsulfate as anticholinesterase, was spiked with carbamazepine as internal standard and alkalized by sodium hydroxide. Liquid-liquid extraction with ethyl ether was used for plasma sample preparation. The chromatographic separation was achieved on a Kromosil ODS C18 column with a mobile phase consisting of 30 mM potassium dihydrogen phosphate buffer (0.16% triethylamine, pH adjusted to 4.9 with phosphoric acid) and acetonitrile (63/37, v/v). The detection was performed simultaneously at wavelengths of 210 and 290 nm. The chromatographic analysis time was 13 min per sample. The calibration curves of all five analytes were linear between 0.05 and 5.0 microg/mL (r(2) > or = 0.998). Precision ranged from 1.4% to 7.9% and accuracy was between 91.7% and 106.5%. The validated method is applicable for simultaneous determination of procaine, lidocaine, ropivacaine, tetracaine and bupivacaine for therapeutic drug monitoring and pharmacokinetic study.

Population pharmacokinetic modelling for enterohepatic circulation of mycophenolic acid in healthy Chinese and the influence of polymorphisms in UGT1A9.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT Mycophenolic acid (MPA) undergoes enterohepatic circulation (EHC) in the body and several population models have been proposed to describe this process using sparse data. Recent studies in Whites have found that polymorphism in UGT1A9 could partly explain the large interindividual variability associated with the pharmacokinetics of MPA. WHAT THIS STUDY ADDS A new population pharmacokinetic model for EHC combining MPA and its main glucuronide metabolite (MPAG) simultaneously was established based on physiological aspects of biliary excretion using intensive sampling data. Pharmacokinetic profiles of MPA and MPAG with the UGT1A9 polymorphism in healthy Chinese were characterized. AIMS To establish a population pharmacokinetic model that describes enterohepatic circulation (EHC) of mycophenolic acid (MPA) based on physiological considerations and to investigate the influence of polymorphisms of UGT1A9 on the pharmacokinetics of MPA. METHODS Pharmacokinetic data were obtained from two comparative bioavailability studies of oral mycophenolic mofetil formulations. Nonlinear mixed effects modelling was employed to develop an EHC model including both MPA and its main glucuronide metabolite (MPAG) simultaneously. Demographic characteristics and UGT1A9 polymorphisms were screened as covariates. RESULTS In total, 590 MPA and 589 MPAG concentration-time points from 42 healthy male volunteers were employed in this study. The chain compartment model included an intestinal compartment, a gallbladder compartment, a central and a peripheral compartment for MPA and a central compartment for MPAG. The typical population clearance (CL/F) estimates with its relative standard error for MPA and MPAG were 10.2 l h(-1) (5.7%) and 1.38 l h(-1) (6.9%), respectively. The amount of MPA recycled in the body was estimated to be 29.1% of the total amount absorbed. Covariate analysis showed that body weight was positively correlated with CL/F of MPA, intercompartment CL/F of MPA and distribution volume of MPA peripheral compartment. Polymorphisms of UGT1A9 did not show any effect on the pharmacokinetics of MPA and MPAG. The model evaluation tests indicated that the proposed model can describe the pharmacokinetic profiles of MPA and MPAG in healthy Chinese subjects. CONCLUSIONS The proposed model may provide a valuable approach for planning future pharmacokinetic-pharmacodynamic studies and for designing proper dosage regimens of MPA.

Association of ABCB1, CYP3A4*18B and CYP3A5*3 genotypes with the pharmacokinetics of tacrolimus in healthy Chinese subjects: a population pharmacokinetic analysis

What is known and Objective:  Tacrolimus (TAC) is metabolized mainly by the CYP3A subfamily and extruded into the intestine by P‐glycoprotein, which is encoded by the ABCB1 gene. Several studies have suggested that the CYP3A5*3 genotype influenced the pharmacokinetics (PK) of TAC. The CYP3A4*18B and CYP3A5*3 alleles are clinically important in Chinese subjects because of their relatively high frequency. The present study aimed at evaluating the effects of ABCB1 (C1236T‐G2677T/A‐C3435T), CYP3A4*18B and CYP3A5*3 genetic polymorphisms on TAC PK in healthy Chinese subjects.

Ginsenoside Rb1 inhibits proliferation and inflammatory responses in rat aortic smooth muscle cells.

Ginsenoside Rb1, a known phytoestrogen, is a major pharmacologically active component in ginseng. The present study was designed to investigate the effect of ginsenoside Rb1 on fetal bovine serum (FBS)-induced proliferation and tumor necrosis factor-α (TNF-α)-evoked inflammatory responses in cultured rat aortic vascular smooth muscle cells (VSMCs). The data showed that Rb1 potently inhibited VSMC proliferation and cell growth induced by 5% FBS. These inhibitory effects were associated with G(1) cell cycle arrest and down-regulation of cell cycle proteins. Treatment with Rb1 reduced FBS-induced extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. Furthermore, TNF-α-evoked inflammatory responses were inhibited by Rb1. Reporter gene assay indicated that Rb1 could transactivate ERβ especially. Moreover, Rb1-mediated inhibition of VSMCs proliferation was greatly blocked by transfection of ERβ siRNA. These results suggest that Rb1 inhibits FBS-induced proliferation and TNF-α-evoked inflammatory responses in VSMCs. The findings presented here highlight the possible therapeutic use of Rb1 in cardiovascular disease.

Population pharmacokinetics of carbamazepine in Chinese epilepsy patients.

Aim To investigate the pharmacokinetic profile of carbamazepine (CBZ) in Chinese epilepsy patients. Materials and Methods Serum samples through concentrations at steady state (n = 687) were collected prospectively from 585 patients during routine clinical care. Data were analyzed by the non-linear mixed-effect modeling (NONMEM) technique with a one-compartment model of first-order absorption and elimination. Results The important determinants of clearance (CL) were total body weight (TBW); dose; patient age over 65 years (E); and comedication with phenytoin (PHT), phenobarbital (PB), or valproic acid (VPA) when VPA daily dose was greater than 18 mg/kg. The final pharmacokinetic model for relative CL and apparent distribution volume (V) were:MATH Conclusion A population pharmacokinetic model was proposed to estimate the individual CL for Chinese patients receiving CBZ in terms of patients dose, TBW, and comedications to establish a priori dosage regimens.

Population pharmacokinetic modeling of steady state clearance of carbamazepine and its epoxide metabolite from sparse routine clinical data.

Objective:  To develop a population pharmacokinetic model to evaluate the effects of variety of covariates on clearance of carbamazepine (CBZ) and its main metabolite carbamazepine‐10,11‐epoxide (CBZE) in Chinese population.

Determination of berberine, palmatine and jatrorrhizine in rabbit plasma by liquid chromatography–electrospray ionization-mass spectrometry

Incurred rabbit plasmas samples were utilized for method quality assessment in this study, where an optimized protein precipitation method for the preparation of rabbit plasma samples and a rapid and sensitive liquid chromatography-electrospray ionization-mass spectrometry for the simultaneous determination of berberine, palmatine and jatrorrhizine was described. Plasma samples (100 μl) were pretreated by protein precipitation with the mixture of 3% formic acid and 50 ng/ml clozapine (internal standard) in acetonitrile followed by LC analysis using a C(18) column and a mobile phase composed of 0.4% formic acid solution and 0.2% formic acid solution of methanol (60:40, v/v) operated at a flow rate of 0.4 ml/min. The analysis was performed in the multiple reaction monitoring mode via electrospray ionization source operating in the positive ionization mode. The method was linear over the concentration range of 0.1-400 ng/ml for all target components. The lower limits of quantification were 0.1 ng/ml for all analytes, all intra- and inter-day precision values were less than 7.10%, and accuracy (bias, %) was within ±7.11%. The mean absolute recovery was more than 72% for all analytes. The validated method has been successfully applied to the pharmacokinetic study of berberine, palmatine and jatrorrhizine in rabbit plasma after oral administration of San-Huang decoction to rabbits.

Stem cell therapy for bone repair: a systematic review and meta‐analysis of preclinical studies with large animal models

Injury to bone is a significant clinical challenge, due to its limited regenerative capacity. The current methods of repairing bone defect are surgical, highly invasive and not always successful. A systematic review and meta‐analysis of preclinical studies involving large animals with bone defects were conducted to determine the treatment outcomes with stem cell therapies.

Validation of Chinese version of the Morisky Medication Adherence Scale in patients with epilepsy

PURPOSE This study aimed to validate a Chinese version of the Morisky Medication Adherence Scale (MMAS-8) in patients with epilepsy. The relationships between adherence, seizure frequency, and adverse effects were assessed using this method. METHODS Data from patients diagnosed with epilepsy at the Department of Neurology of Huashan Hospital were collected between January and June 2013. To validate the MMAS-8, internal consistency, test-retest reliability, and factor analysis were calculated. Relationships between adherence, seizure frequency, and adverse effects were assessed using Pearsons correlation. RESULTS One hundred and eleven patients were recruited. The MMAS-8 had moderate internal consistency (Cronbachs α=0.556) and good test-retest reliability (intraclass correlation coefficient=0.729). The MMAS-8 adherence rate was 79.2%. MMAS-8 adherence was negatively correlated with seizure frequency and adverse effects (r = -0.708, p<0.001; r = -0.484, p<0.001). CONCLUSION The MMAS-8 scale can be used as a tool to assess medication adherence in Chinese patients with epilepsy. Better seizure control and lower rates of adverse effects were significantly correlated with higher adherence scores.