LC-MS/MS method for the determination of an anti-tumor compound C17 in nude mice plasma and its application to a pharmacokinetic study / 药学学报

C17 is an orally available anti-tumor compound inhibiting cancer stem cell (CSC). In this study, a stable, sensitive and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established and validated, and was further applied to a pharmacokinetic study in nude mice receiving C17 by gavage. Using propranolol as the internal standard, the plasma samples were pre-treated by precipitation with methanol and analyzed on an Intersil C8-3 column (100 mm × 2.1 mm, 3 μm), and gradient elution was performed with a mobile phase consisting of 0.1% formic acid aqueous and solution mixed up by 90% isopropanol and 10% acetonitrile. The analyte was detected by a triple quadrupole tandem mass spectrometer, and multiple reaction monitoring was employed to select C17 at m/z 439.3/247.1 and propranolol at m/z 260.2/116.2 in the positive ion mode. The calibration curves were linear (r > 0.995) over the range of 5-800 ng·mL-1. The intra- and inter-day precisions and accuracies were 7.42%-13.22% and -8.99%-8.81% respectively. The method was successfully applied to a PK study in nude mice administered with a single oral dose of 50 mg·kg-1 C17, and the PK data were analyzed with non-linear mixed effect model (NONMEM). Two separated absorption peaks were found in the PK curve of C17, and a two-compartment model with two sequential first-order absorption rate was utilized to describe the PK properties of C17, and the model could provide insights into the physiological process and exposure of C17 in nude mice. All animal experiments were in strict accordance with the regulations of the Biomedical Ethics Committee of Peking University.

Pharmacokinetic/pharmacodynamic modeling of the antitumor action of bispecific CD3/EpCAM antibody M701 in human colorectal cancer xenograft mice / 药学学报

M701 is a bispecific CD3/EpCAM T-cell engager antibody for the treatment of malignant ascites. We developed a population pharmacokinetic/pharmacodynamic (PK/PD) model to quantitatively describe and predict the antitumor effect of M701 in human colorectal cancer xenograft mice. We developed the M701 PK model based on plasma concentration data after i.v. administration. A tumor growth model for human colorectal cancer xenograft was developed to evaluate the antitumor effect of M701. We additionally simulated the inhibitory effect of M701 on tumor volume under different dose regimens based on a PK/PD model. A two-compartment model was developed to predict the PK in human colorectal cancer xenograft mice. The relationship between the M701 concentration and tumor growth inhibition was characterized by a combined Simeoni tumor growth/transit compartment model. The estimated pharmacodynamic parameters were related to the tumor growth characteristics λ0 (0.212 d-1) and λ1 (0.044 7 cm3·d-1), to the drug potency k2 (0.071 5 mL·ng-1·d-1), and to the kinetics of tumor cell death k1 (2×10-5 d-1). A model visual predictive check showed that both the PK model and the tumor growth model closely fit the observed data. Simulated tumor growth after administration of M701 (0.5 mg·kg-1 every 6 days and 0.25 mg·kg-1 every 3 days) could be effectively inhibited. This population PK/PD model of M701 provides insight into the antitumor effect of M701 and supports the further therapeutic development of M701.

Population pharmacokinetics and its application in new drug research / 药学学报

Population pharmacokinetics is an emerging discipline developed from the combination of classical pharmacokinetic compartment model and statistics principles, which has been received more and more attention in recent years. Population pharmacokinetics plays important roles in all stages of new drug research. In the early preclinical phase, population pharmacokinetic analysis can help to achieve the preliminary prediction of parameters from animal to human, optimize clinical trial designs, and shorten the time required for new drugs from laboratory to clinical trials. In clinical trials and applications stage, population pharmacokinetic research can help researchers investigate the related covariates that affecting pharmacokinetic behavior of patients comprehensively, and find potential drug-drug interactions in clinical. In addition, population pharmacokinetics has a unique advantage in pediatric drug development due to its strong analysis ability of sparse data. This paper provides a summary on the history and methods of population pharmacokinetics, and the application in new drug discovery and development.

Using the cumulative odds Logit model to explore the application of the questionnaire derived from PANSS / 药学学报

Currently, aripiprazole, olanzapine and risperidone are three anti-psychiatry agents commonly used in the treatment of schizophrenia. Although the efficacy of these drugs is good, schizophrenia cannot be completely cured yet. Patients need long-term medication. The family members of patients may play a key role to understand the disease status of patients after patient discharge from hospital. PANSS is a commonly used scale in the clinic to evaluate the disease status and drug effects of anti-psychiatry agents. It was professionally written, and is not user friendly to amateurs. In the previous study, we developed a questionnaire for patient's family members to monitor the disease status. In this study, we explored the correlations between the results of questionnaire and 5 kinds of disease state corresponding to different PANSS score interval using the cumulative odds Logit model. The final results show that the model had relatively good prediction ability for aripiprazole, olanzapine and risperidone, suggesting that the questionnaire has an extensive prospect of clinical applications.

Current applications of dexamethasone for cancer treatment / 药学学报

Dexamethasone is a synthetic glucocorticoid that is widely used in clinical due to its multiple pharmacological effects. Recently, dexamethasone is increasingly utilized in anti-cancer therapy. It is frequently used to prevent side effects of chemotherapy such as nausea, vomiting and pain, as well as to increase the anti-tumor activity of the cancer chemotherapeutic agents as a chemosensitizer and to inhibit tumor growth as an anti-cancer agent in some certain cancers. Dexamethasone produces the effects in anti-inflammation, anti-angiogenesis, control of estrogen activity and so on, by binding to glucocorticoid receptor to regulate gene expression of some important bio-signal molecules. Those signal pathways could interfere with the transcription of various factors which can regulate proliferation, invasion and metastasis of tumors.

Population pharmacokinetics of vancomycin and prediction of pharmacodynamics in the Chinese people / 药学学报

Population pharmacokinetics of vancomycin (VAN) in the Chinese patients was described by using nonlinear mixed-effects modeling (NONMEM). 619 VAN serum concentrations data from 260 patients including 177 males and 83 females were collected separately from two centers. A one-compartment model was used to describe this sparse data. No significant difference was observed between two center datasets by introducing SID covariate. The final model was as CL= (θ (base0+ θ(max) x(1 -e(-θ(Age)(Age/72) and V = θ x θ (Age)(Age/72). The creatinine clearance (CL(Cr)) and Age were identified as the most significant covariate in the final model. Typical values of clearance (CL) and volume of distribution (V) in the final model were 2.91 L x h(-1) and 54.76 L, respectively. Internal model validation by Bootstrap and NPDE were performed to evaluate the robustness and prediction of the final model. The median and 95% confidence intervals for the final model parameters were based on 1000 Bootstraps. External model evaluation was conducted using an independent dataset that consisted of 34 patients to predict model performance. Pharmacodynamic assessment for VAN by AUC (0-24 h) to MIC ratios of over 400 was considered to be the best to predict treatment outcomes for patients. AUC (0-24 h) was calculated by clearance based on the above population model. The results indicate that the conventional dosing regimen probably being suboptimal concentrations in aged patients. The approach via population pharmacokinetic of VAN combined with the relationship of MIC, Age, CL(Cr) and AUC(0-24 h)/MIC can predict the rational dose for attaining efficacy.

A model-based meta-analysis to compare urate-lowering response rate of febuxostat and allopurinol in gout patient / 药学学报

This study aims to compare the urate-lowering response rate of febuxostat and allopurinol in gout patient using a model-based meta-analysis. The literature search identified 22 clinical trials of gout with a total of 43 unique treatment arms that met our inclusion criteria, and a total of 6 365 gout patients were included in the study. The response rates of allopuriol and febuxostat were characterized by Tmax model and Emax model respectively, and the effect of baseline serum uric acid (sUA) and patient type on the drug effect was tested. The results showed that allopurinol can reach an average maximum response rate of 50.8% while febuxostat can reach a 100% response rate within a very short time, and the ED50 was 34.3 mg. Covariate analysis revealed that baseline sUA has a negative effect on response rate of allopurinol, and a positive effect on the predicted ED50 of febuxostat. For patients who had shown inadequate response to prior allopurinol treatment, the average response rate was about half that of the allopurinol responder patients.

Simultaneous quantitation of artemisinin, arteannuin B, artemisic acid, and scopoletin in mice plasma by HPLC-MS / 中国中药杂志

The objective of this study is to develop a sensitive and reliable high-performance liquid chromatography mass spectrometry (LC-MS) method for simultaneous determination of artemisinin, arteannuin B, artemisic acid, and scopoletin, and study the pharmacokinetics of the four constituents in mouse serum after oral administration of the four components to mice. The analytical column used was Agilent Zorbax SB-C18 (2.1 mm x 150 mm, 5 mm). The mobile phase was acetonitrile: 0.5% acetic acid (60: 40) and the flow rate was 0.3 mL x min(-1). The temperature of the column was 40.0 degrees C. In this condition, we established an analysis method to simultaneously determine the four components. A sensitive and specific liquid chromatography-mass spectrometric (LC-MS) method was developed and validated for the determination of artemisin in derivatives in mice plasma. The method we established has a linear range of 5-3 000 μg x L(-1) with a good sensitivity and specificity for all of the four components. This method is simple, rapid, accurate and suitable for the determination of the content of the four compounds.

The therapeutic drug monitoring network server of tacrolimus for Chinese renal transplant patients / 药学学报

This study is to develop a therapeutic drug monitoring (TDM) network server of tacrolimus for Chinese renal transplant patients, which can facilitate doctor to manage patients' information and provide three levels of predictions. Database management system MySQL was employed to build and manage the database of patients and doctors' information, and hypertext mark-up language (HTML) and Java server pages (JSP) technology were employed to construct network server for database management. Based on the population pharmacokinetic model of tacrolimus for Chinese renal transplant patients, above program languages were used to construct the population prediction and subpopulation prediction modules. Based on Bayesian principle and maximization of the posterior probability function, an objective function was established, and minimized by an optimization algorithm to estimate patient's individual pharmacokinetic parameters. It is proved that the network server has the basic functions for database management and three levels of prediction to aid doctor to optimize the regimen of tacrolimus for Chinese renal transplant patients.

Comparison study of model evaluation methods: normalized prediction distribution errors vs. visual predictive check / 药学学报

The objective of this study is to compare the normalized prediction distribution errors (NPDE) and the visual predictive check (VPC) on model evaluation under different study designs. In this study, simulation method was utilized to investigate the capability of NPDE and VPC to evaluate the models. Data from the false models were generated by biased parameter typical value or inaccurate parameter inter-individual variability after single or multiple doses with the same sampling time or multiple doses with varied sampling time, respectively. The results showed that there was no clear statistic test for VPC and it was difficult to make sense of VPC under the multiple doses with varied sampling time. However, there were corresponding statistic tests for NPDE and the factor of study design did not affect NPDE significantly. It suggested that the clinical data and model which VPC was not fit for could be evaluated by NPDE.

Application of Fourier amplitude sensitivity test in Chinese healthy volunteer population pharmacokinetic model of tacrolimus / 药学学报

In this study, we evaluated the influence of different variance from each of the parameters on the output of tacrolimus population pharmacokinetic (PopPK) model in Chinese healthy volunteers, using Fourier amplitude sensitivity test (FAST). Besides, we estimated the index of sensitivity within whole course of blood sampling, designed different sampling times, and evaluated the quality of parameters' and the efficiency of prediction. It was observed that besides CL1/F, the index of sensitivity for all of the other four parameters (V1/F, V2/F, CL2/F and k(a)) in tacrolimus PopPK model showed relatively high level and changed fast with the time passing. With the increase of the variance of k(a), its indices of sensitivity increased obviously, associated with significant decrease in sensitivity index for the other parameters, and obvious change in peak time as well. According to the simulation of NONMEM and the comparison among different fitting results, we found that the sampling time points designed according to FAST surpassed the other time points. It suggests that FAST can access the sensitivities of model parameters effectively, and assist the design of clinical sampling times and the construction of PopPK model.

Population pharmacokinetics research of clozapine in Chinese schizophrenic patients / 药学学报

The goal of this study is to investigate the population pharmacokinetics of oral given clozapine in Chinese schizophrenic patients and to identify possible relationships between population parameters and covariates including demography factors and CYP1A2 genetic polymorphism, so as to create the population pharmacokinetics model to guide individual clinical delivery. Details of drug dosage history, sampling time and concentration of 626 data points from 183 patients were collected retrospectively. The 183 patients were randomly allocated either to the index group (n = 168) or to the validation group (n = 15). Population pharmacokinetic data analysis was performed using the nonlinear mixed-effects model (NONMEM) program on the index group. The values of apparent clearance (CL/F), apparent volume of distribution (V/F) and the constant of absorption rate were estimated. A number of covariates including demographic index, coadministration of other drugs and CYP1A2 genotypes were evaluated statistically for their influence on these parameters. The final population model related clearance with day-dose/BSA (DBSA) and smoke habit (SMOK). Predictive performance of the final model evaluated with the validation group showed insignificant bias between observed and model predicted concentrations. Typical value of CL/F (non-smoking group), V/F and the constant of absorption rate were 28.5 L x h(-1) (5.05%), 1 290 L (16.7%) and 2.26 h(-1) (fixed), inter-patient variability (CV) in CL/F and V/F was) 42.2% and 10.0%, respectively. It was observed that the values of CL/F in the two smoking groups were higher than that in the non-smoking group. The residual variability (SD) between observed and model-predicted concentrations was 45.8 microg x L(-1).

Progress in the study of response surface modeling in investigation of drug-drug interaction in anesthetic drugs / 药学学报

As a novel and effective approach, response surface model is used in the study of drug-drug interactions. When two drugs are used simultaneously, this model can be applied to estimate the key characters of the response surface, to find the desired response region by optimal drugs combination, to explore the mechanism of drug-drug interactions, and thus to guide sound clinical application and reduce the risk and cost. In this article, the model's basic mathematical and pharmacological concepts are introduced, and its research progresses are reviewed.