Comparative Efficacy of Drugs for the Treatment of Chronic Constipation: Quantitative Information for Medication Guidelines.

BACKGROUND: Quantitative information is scarce with regard to guidelines for currently prescribed medications for constipation. Furthermore, these guidelines do not reflect the differences in the number of bowel movements caused by each drug. GOALS: In this study, we used a model-based meta-analysis to quantitatively estimate the deviations from the baseline number of spontaneous bowel movements (SBMs) and complete spontaneous bowel movements (CSBMs) associated with pharmacotherapy for chronic constipation to bridge the knowledge gap in the guidelines for current medications. STUDY: A comprehensive survey was conducted using literature databases. In this study, we also included randomized placebo-controlled trials on chronic constipation. Pharmacodynamic models were established to describe the time course of the numbers of SBMs and CSBMs produced by each drug. RESULTS: Data from 20 studies (comprising 9998 participants and 8 drugs) were used to build this model. The results showed that bisacodyl had the greatest effect on increasing the frequency of bowel movements, whereas plecanatide yielded the lowest increase in the number of SBMs and CSBMs. After eliminating the placebo effect, the maximal increase in bowel movement frequency associated with bisacodyl was 6.8 for SBMs (95% confidence interval: 6.1-7.6) and 4.7 for CSBMs (95% confidence interval: 4.3-5.1) per week. These numbers are ∼4 times higher than the number of bowel movements produced by plecanatide. The change in the frequency of SBMs and CSBMs for other drugs, such as sodium picosulfate, velusetrag, linaclotide, elobixibat, lubiprostone, and prucalopride, was similar. The highest increases in the frequency of SBM and CSBM were 2.5 to 4 and 1 to 2.1 per week, respectively. Bisacodyl had the most noticeable loss of efficacy between week 1 and week 4; it reduced the frequencies of SBMs and CSBMs by 2.3 and 2.2, respectively. By contrast, the changes in the frequencies of SBMs and CSBMs were not as great with other drugs. CONCLUSIONS: The data provided in this study may be a valuable supplement to the medication guidelines for the treatment of chronic constipation.

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.

Interethnic scaling of fraction unbound of a drug in plasma and volume of distribution: an analysis of extrapolation from Caucasians to Chinese.

PURPOSE: Prospective prediction of pharmacokinetic properties for individuals of different ethnic groups could provide useful information for the design of multiregional clinical trials. The accuracy of interethnic scaling of fraction unbound (fu) of a drug could determine in large part the predictive capability of volume of distribution as well as renal clearance. As such, exploring the interethnic extrapolation of fu from healthy Caucasian to Chinese subjects and associated effect on the scaling of volume of distribution is highly warranted. METHODS: This study assessed the interethnic scaling of fu from healthy Caucasians to Chinese by using physiologically based principles and verified the approach after examining with experimentally determined fu values of a variety of reference compounds with differing binding characteristics. Moreover, the fundamental assumption of interethnic extrapolation of volume of distribution (Vd), namely the equivalency of unbound Vd (Vd,u) across different ethnic groups, was tested on the basis of observed Vd data derived from comprehensive literature analysis and scaled fu values through qualified extrapolation method. RESULTS: The interethnic extrapolation approach of fu provided a high accuracy with 94.7% scaled Chinese fu values (n = 19) being within a 1.25%-fold error range. Specifically, 100% of scaled Chinese fu values for the albumin-bound compounds and 90% for those bound to alpha 1-acid glycoprotein fell within the 1.25%-fold error range. All the percentage prediction errors of scaled Chinese fu values were ≤ 30%, with a majority of those ≤ 20%. Additionally, correlation between the prediction errors and the observed fu levels was not observed. Regarding interethnic scaling of Vd, the bodyweight-normalized Vd,u instead of Vd was similar across ethnic groups. CONCLUSION: The current study verified for the first time the ability to scale Chinese fu from Caucasian values after examining with experimentally determined fu values of a variety of reference compounds. Similarities in bodyweight-normalized Vd,u between non-obese Caucasians and Chinese have also been shown for the first time. This investigation could greatly enhance the confidence in the interethnic extrapolation of fu and Vd from healthy non-obese Caucasian to Chinese subjects.

Population pharmacokinetics of moxifloxacin and its concentration-QT interval relationship modeling in Chinese healthy volunteers.

Moxifloxacin (MX) is an 8-methoxyquinolone antimicrobial drug, which is often used as a positive control in thorough QT (TQT) studies. In the present study we established the population pharmacokinetics model of MX and the relationship of MX concentrations with the QT and various corrected QT (QTc) intervals, and compared the results with other ethnicities. The MX data used for modeling were obtained from a published TQT interval prolongation study of antofloxacin with MX as the positive control. In this four-period crossover study, 24 adult Chinese healthy volunteers received either 200 or 400 mg of oral antofloxacin once daily, 400 mg of MX, or a placebo. Population concentration-effect models were used to investigate the relationship between MX concentrations and QT interval prolongation, baseline-adjusted QTc (ΔQTc), or ΔQTc adjusted with time-matched placebo corrections (ΔΔQTc). The influencing factors of MX PK and the concentration-QTc relationship were determined through covariate screening. Simulation studies were conducted in R2.30 by using the final model with the estimated population mean and intra-individual and inter-individual variability. The estimated pharmacokinetic parameters and the estimated slope of the MX concentration-QT/ΔQTc/ΔΔQTc relationship were described using models and were compared to results for other ethnicities from the literature. We showed that the population pharmacokinetic parameter estimates for total plasma clearance (CL/F), the volume of distribution of central compartment (Vc/F), the distributional clearance in plasma (Q), the volume of distribution of peripheral compartment (Vp/F), and the absorption rate constant (Ka) were 8.22 L/h, 104 L, 3.98 L/h, 37.7 L, and 1.81 1/h, respectively. There was no significant covariate included in the final model. QT interval prolongation of MX estimates ranging from 9.77 to 12.91 ms at the mean average maximum concentration of MX (4.36 µg/mL) and a mean slope ranging from 2.33 to 2.96 ms per µg/mL. In conclusion, no ethnic differences were observed for the MX pharmacokinetic parameters and QT interval prolongation.

Population pharmacokinetics of lyophilized recombinant glucagon-like peptide-1 receptor agonist (recombinant exendin-4, rE-4) in Chinese patients with type 2 diabetes mellitus
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OBJECTIVE: To investigate the population pharmacokinetics of lyophilized recombinant glucagon-like peptide-1 receptor agonist (rE-4) in Chinese patients with type 2 diabetes mellitus (T2DM) for plasma concentration estimation and individualized treatment. METHODS: Twelve patients with T2DM were enrolled to receive subcutaneous injections of rE-4 at 5 µg twice daily for 84 days. Administration dosage was adjusted from 5 µg to 10 µg twice daily at day 29 in case of glycated albumin (GA) ≥ 17%. The population pharmacokinetic model was developed in the nonlinear mixed-effects modeling software NONMEM. RESULTS: The data were best described by a two-compartment model with first-order absorption and elimination. The outcome parameters were as follows: apparent clearance (CL/F) 6.67 L/h, apparent distribution volume of central compartment (Vc/F) 19.4 L, absorption rate constant (Ka) 1.39 h-1, apparent distribution volume of peripheral compartment (Vp/F) 22.6 L, intercompartmental clearance (Q/F) 1.28 L/h. The interindividual variabilities for CL/F, Vc/F, Ka, and Q/F were 64.4%, 57.7%, 45.5%, and 153.3%, respectively. The intra-individual variability of proportional error model was 41.7%. No covariate was screened out that showed significant influence on the model parameters. CONCLUSIONS: The established two-compartment model with first-order absorption and elimination successfully described the pharmacokinetic characteristics of rE-4 in Chinese patients with T2DM.
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[Computerized system validation of clinical researches].

Validation is a documented process that provides a high degree of assurance. The computer system does exactly and consistently what it is designed to do in a controlled manner throughout the life. The validation process begins with the system proposal/requirements definition, and continues application and maintenance until system retirement and retention of the e-records based on regulatory rules. The objective to do so is to clearly specify that each application of information technology fulfills its purpose. The computer system validation (CSV) is essential in clinical studies according to the GCP standard, meeting product's pre-determined attributes of the specifications, quality, safety and traceability. This paper describes how to perform the validation process and determine relevant stakeholders within an organization in the light of validation SOPs. Although a specific accountability in the implementation of the validation process might be outsourced, the ultimate responsibility of the CSV remains on the shoulder of the business process owner-sponsor. In order to show that the compliance of the system validation has been properly attained, it is essential to set up comprehensive validation procedures and maintain adequate documentations as well as training records. Quality of the system validation should be controlled using both QC and QA means.

[Exploration of visual check approaches in clinical data management].

Due to a great amount of data in clinical trials, the data cleansing needs to adopt a variety of measures, including the latest developed visual check approach. According to the different types of clinical data and the different stages in the course of clinical data management, this study reviews 8 types of visual graphics that show the relevance and trend among the data. The series of graphics can rapidly detect abnormal data, monitor clinical research in real-time, make the data management process much easier and improve the clinical trial efficiency and data quality.

[Comparison of paper and electronic data management in clinical trials].

Electronic case report forms (eCRFs) instead of the traditional paper case report forms (pCRFs) are increasingly used by investigators and sponsors of clinical research. We include a total of 14 phase III studies (8 pCRF, 6 eCRF) to compare paper and electronic data documentation both quantitatively and qualitatively in clinical studies. The result suggests that adaptions of electronic data capture (EDC) in clinical trials have the advantages in optimization of data capture process, improvement of data quality and earlier clinical decision compared to paper-based methods. Furthermore, the successful implementation of EDC requires accouplements with corresponding data management processes and reallocation of resources.

[Quality control of clinical data management based on EDC].

With the wide application of electronic data management (EDC), the data management is shifting to a new mode. In order to recognize the advantages of EDC, we choose 20 representative registered clinical trials, which involve 5 404 subjects and 321 sites. We found that EDC has many beneficial impacts on the course of clinical trial data management, including the process of data collection, data cleaning, data quality control and clinical trial decision-making. The result also provides a reference for the adoption of EDC in clinical trials.

Random sparse sampling strategy using stochastic simulation and estimation for a population pharmacokinetic study.

The purpose of this study was to use the stochastic simulation and estimation method to evaluate the effects of sample size and the number of samples per individual on the model development and evaluation. The pharmacokinetic parameters and inter- and intra-individual variation were obtained from a population pharmacokinetic model of clinical trials of amlodipine. Stochastic simulation and estimation were performed to evaluate the efficiencies of different sparse sampling scenarios to estimate the compartment model. Simulated data were generated a 1000 times and three candidate models were used to fit the 1000 data sets. Fifty-five kinds of sparse sampling scenarios were investigated and compared. The results showed that, 60 samples with three points and 20 samples with five points are recommended, and the quantitative methodology of stochastic simulation and estimation is valuable for efficiently estimating the compartment model and can be used for other similar model development and evaluation approaches.

Azimuthal and radial variations in sap flow and its effects on the estimation of transpiration for Picea mongolica.

In this study, we applied thermal dissipation probe technology to examine sap flow in various directions (east, south, west, and north) and at different depths (0-2, 2-4, 4-6 cm) within the stem of natural Picea mongolica trees in the eastern of Otindag Sandy Land to provide a scientific basis for accurately quantifying water consumption of P. mongolica forests through transpiration and to enhance the understanding of water relations. The results showed that the diurnal variation of sap flow in different directions displayed a unimodal curve, with the sap flow sequence being south>east>west>north. The sap flow at different sapwood depths exhibited an obvious unimodal curve, with a significant decrease as sapwood depth increased. Compared with that calculated from the mean sap flux density in four directions (23.57 kg·d-1), water consumption calculated using the mean value in south-east, east-west, south-west, north-east, north-south, and north-west was overestimated by 10.2%, 5.5%, 14.5%, and underestimated by 12.3%, 8.2%, 9.8%, respectively. The water consumption calculated using the values from the east, south, and west was overestimated by 6.1%, 14.4%, and 15.4%, respectively, and underestimated by 30.7% in the north. In addition, compared with the water consumption calculated from the mean value in three sapwood depths (48.51 kg·d-1), that calculated using sap flux density at sapwood depths of 0-2, 2-4, and 4-6 cm were overestimated by 18.8%, underestimated by 1.7%, and underestimated by 62.9%, respectively. These results indicated that sap flow of P. mongolica had significant azimuthal and radial variations, which considerably influence the estimation of tree water consumption. Installing probes at 0-2 cm simultaneously in both the north and east of the trunk could effectively reduce the estimation error of whole-tree water consumption by 4.2%. This approach enabled the accurate quantification of water consumption of individual P. mongolica trees in sandy areas, thereby improving the precision of transpiration water consumption estimates scaling up from individual level to stand level.

A cyclic fluctuation model for 24-h ambulatory blood pressure monitoring in Chinese patients with mild to moderate hypertension.

AIM: The conventional method for analyzing 24-h ambulatory blood pressure monitoring (24-h ABPM) is insufficient to deal with the large amount of data collected. The aim of this study was to develop a novel cyclic fluctuation model for 24-h ABPM in Chinese patients with mild to moderate hypertension. METHODS: The data were obtained from 4 independent antihypertensive drug clinical trials in Chinese patients with mild to moderate hypertension. The measurements of 24-h ABPM at the end of the placebo run-in period in study 1 were used to develop the cyclic fluctuation model. After evaluated, the structural model was used to analyze the measurements in the other 3 studies. Models were fitted using NONMEM software. RESULTS: The cyclic fluctuation model, which consisted of 2 cosine functions with fixed-effect parameters for rhythm-adjusted 24-h mean blood pressure, amplitude and phase shift, successfully described the blood pressure measurements of study 1. Model robustness was validated by the bootstrap method. The measurements in the other 3 studies were well described by the same structural model. Moreover, the parameters from all the 4 studies were very similar. Visual predictive checks demonstrated that the cyclic fluctuation model could predict the blood pressure fluctuations in the 4 studies. CONCLUSION: The cyclic fluctuation model for 24-h ABPM deepens our understanding of blood pressure variability, which will be beneficial for drug development and individual therapy in hypertensive patients.

Limited sampling strategy models for estimating the AUC of gliclazide in Chinese healthy volunteers.

The aim of this work is to reduce the cost of required sampling for the estimation of the area under the gliclazide plasma concentration versus time curve within 60 h (AUC0-60t ). The limited sampling strategy (LSS) models were established and validated by the multiple regression model within 4 or fewer gliclazide concentration values. Absolute prediction error (APE), root of mean square error (RMSE) and visual prediction check were used as criterion. The results of Jack-Knife validation showed that 10 (25.0 %) of the 40 LSS based on the regression analysis were not within an APE of 15 % using one concentration-time point. 90.2, 91.5 and 92.4 % of the 40 LSS models were capable of prediction using 2, 3 and 4 points, respectively. Limited sampling strategies were developed and validated for estimating AUC0-60t of gliclazide. This study indicates that the implementation of an 80 mg dosage regimen enabled accurate predictions of AUC0-60t by the LSS model. This study shows that 12, 6, 4, 2 h after administration are the key sampling times. The combination of (12, 2 h), (12, 8, 2 h) or (12, 8, 4, 2 h) can be chosen as sampling hours for predicting AUC0-60t in practical application according to requirement.

[Treating menopause syndrome by kuntal capsule and hormone replacement therapy: a meta-analysis of efficacy and safety comparison].

OBJECTIVE: To evaluate the efficacy and safety of Kuntai Capsule (KC) and hormone replacement therapy (HRT) in treating menopause syndrome by Meta-analysis. METHODS: Randomized controlled trials were electronically retrieved from PubMed, EMbase, The Cochrane Library, CBM, CNKI, Chinese Doctoral Dissertation Full Text Database, Chinese Outstanding Masters' Dissertation Full Text Database, and VIP database, Wanfang Database, and some other related papers were manually checked. All papers were assessed according to the Cochrane Handbook for Systematic Reviews of interventions and then effective data were analyzed by RevMan 5.0.2 Software. RESULTS: Eight randomized control trials involving 675 patients were included. Results of Meta-analysis showed that there was no statistical difference in the Kupperman Menopausal Scores [MD = 1.91, 95% CI (-0.31, 4.12)] and the effective rate of Kupperman Menopausal Scores [OR = 1.37, 95% CI (0.66, 2.85)] between the KC group and the estrogen replacement therapy group (P > 0.05). Compared with the KC group, the E2 level [MD = -12.8, 95% CI (-22.85, -2.76)] and the FSH level [MD = 17.96, 95% CI (3.03, 32.88)] could be significantly improved in the estrogen replacement therapy group. Compared with the estrogen replacement group, KC could significantly reduce the total incidence of adverse reactions [OR = 0.41, 95% CI (0.24, 0.73)], the incidence of breast distending pain [OR = 0.65, 95% CI (0.42, 1.00)], and the incidence of vaginal bleeding [OR = 0.26, 95% CI (0.17, 0.40) ] (P < 0.05). CONCLUSIONS: The current limited evidence showed that, when compared with the estrogen replacement therapy group, KC could also improve climacteric symptoms. It was inferior to the estrogen replacement therapy group in improving in vivo hormone levels. But it was superior in reducing the incidence of adverse reactions, breast distending pain, and vaginal bleeding.

Efficacy and safety of Lianhua Qingwen capsules combined with standard of care in the treatment of adult patients with mild to moderate COVID-19 (FLOSAN): protocol for a randomized, double-blind, international multicenter clinical trial.

Background: Effective anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) drugs are not only the next defense after vaccines but also the key part of establishing a multi-tiered coronavirus disease 2019 (COVID-19) prevention and control system. Previous studies had indicated that Lianhua Qingwen (LHQW) capsules could be an efficacious Chinese patent drug for treating mild to moderate COVID-19. However, pharmacoeconomic evaluations are lacking, and few trials have been conducted in other countries or regions to evaluate the efficacy and safety of LHQW treatment. So, this study aims to explore the clinical efficacy, safety, and economy of LHQW for treating adult patients with mild to moderate COVID-19. Methods: This is a randomized, double-blind, placebo-controlled, international multicenter clinical trial protocol. A total of 860 eligible subjects are randomized at a 1:1 ratio into the LHQW or placebo group to receive two-week treatment and follow-up visits on days 0, 3, 7, 10, and 14. Clinical symptoms, patient compliance, adverse effects, cost scale, and other indicators are recorded. The primary outcomes will be the measured median time to sustained improvement or resolution of the nine major symptoms during the 14-day observation period. Secondary outcomes regarding clinical efficacy will be evaluated in detail on the basis of clinical symptoms (especially body temperature, gastrointestinal symptoms, smell loss, and taste loss), viral nucleic acid, imaging (CT/chest X-ray), the incidence of severe/critical illness, mortality, and inflammatory factors. Moreover, we will assess health care cost, health utility, and incremental cost-effectiveness ratio (ICER) for economic evaluation. Discussion: This is the first international multicenter randomized controlled trial (RCT) of Chinese patent medicine for the treatment of early COVID-19 in accordance with WHO guidelines on COVID-19 management. This study will help clarify the potential efficacy and cost-effectiveness of LHQW in the treatment of mild to moderate COVID-19, facilitating decision-making by healthcare workers. Registration: This study is registered at the Chinese Clinical Trial Registry, with registration number: ChiCTR2200056727 (date of first registration: 11/02/2022).

Simulation of the pharmacokinetics of bisoprolol in healthy adults and patients with impaired renal function using whole-body physiologically based pharmacokinetic modeling.

AIM: To develop and evaluate a whole-body physiologically based pharmacokinetic (WB-PBPK) model of bisoprolol and to simulate its exposure and disposition in healthy adults and patients with renal function impairment. METHODS: Bisoprolol dispositions in 14 tissue compartments were described by perfusion-limited compartments. Based the tissue composition equations and drug-specific properties such as log P, permeability, and plasma protein binding published in literatures, the absorption and whole-body distribution of bisoprolol was predicted using the 'Advanced Compartmental Absorption Transit' (ACAT) model and the whole-body disposition model, respectively. Renal and hepatic clearances were simulated using empirical scaling methods followed by incorporation into the WB-PBPK model. Model refinements were conducted after a comparison of the simulated concentration-time profiles and pharmacokinetic parameters with the observed data in healthy adults following intravenous and oral administration. Finally, the WB-PBPK model coupled with a Monte Carlo simulation was employed to predict the mean and variability of bisoprolol pharmacokinetics in virtual healthy subjects and patients. RESULTS: The simulated and observed data after both intravenous and oral dosing showed good agreement for all of the dose levels in the reported normal adult population groups. The predicted pharmacokinetic parameters (AUC, C(max), and T(max)) were reasonably consistent (<1.3-fold error) with the observed values after single oral administration of doses ranging from of 5 to 20 mg using the refined WB-PBPK model. The simulated plasma profiles after multiple oral administration of bisoprolol in healthy adults and patient with renal impairment matched well with the observed profiles. CONCLUSION: The WB-PBPK model successfully predicts the intravenous and oral pharmacokinetics of bisoprolol across multiple dose levels in diverse normal adult human populations and patients with renal insufficiency.

Dose findings of antofloxacin hydrochloride for treating bacterial infections in an early clinical trial using PK-PD parameters in healthy volunteers.

AIM: To find an appropriate dose regimen of the novel antibacterial agent antofloxacin for a phase II clinical trial using a population pharmacokinetic (PPK) study in healthy volunteers and the minimum inhibitory concentration (MIC) as pharmacodynamic (PD) parameters. METHODS: Twenty-four healthy volunteers were enrolled in a double-blind crossover study and received antofloxacin (200 or 400 mg/d, po) for consecutive 5 d with 10 d washout between two separate periods. Blood concentrations were analyzed using HPLC with a UV-Vis detector. The values of area under the curve (AUC) with covariates were obtained from a PPK model, and the MICs came from the previous in vitro studies. The dose regimen was determined for the phase II clinical trial according to the ratio (>20) of AUC/MIC, and the efficacy of the dose was evaluated by the trial. RESULTS: A two-compartment model best described the time-concentration data with first-order absorption. The PPK parameter estimates for CL, V(c), Q, V(p) and K(A) are 8.34 L/h, 142 L, 15.9 L/h, 52.2 L and 4.64 1/h, respectively. The covariates sex for K(A), weight for CL, weight for V(c) and interoccasion variability were included in the final model. The AUC/MIC was calculated based on the PPK model and the MIC of antofloxacin for Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus and Staphylococcus epidermidis were determined in previous researches. The 400 mg loading dose with 200 mg/d maintenance dose was recommended and confirmed by the phase II trial. CONCLUSION: The ratio of AUC from the PPK model vs MIC as the PD parameter can be applied in a dose-finding trial of antofloxacin in treatment of bacterial infections. The PPK model suggests that sex and body weight may be considerations in regards to individual therapy, which should be investigated in larger clinical trials and serve as a potential reference for clinical therapies.

Population pharmacokinetics and pharmacodynamics of bivalirudin in young healthy Chinese volunteers.

AIM: To investigate the population pharmacokinetics (PK) and pharmacodynamics (PD) of bivalirudin, a synthetic bivalent direct thrombin inhibitor, in young healthy Chinese subjects. METHODS: Thirty-six young healthy volunteers were randomly assigned into 4 groups received bivalirudin 0.5 mg/kg, 0.75 mg/kg, and 1.05 mg/kg intravenous bolus, 0.75 mg/kg intravenous bolus followed by 1.75 mg/kg intravenous infusion per hour for 4 h. Blood samples were collected to measure bivalirudin plasma concentration and activated clotting time (ACT). Population PK-PD analysis was performed using the nonlinear mixed-effects model software NONMEM. The final models were validated with bootstrap and prediction-corrected visual predictive check (pcVPC) approaches. RESULTS: The final PK model was a two-compartment model without covariates. The typical PK population values of clearance (CL), apparent distribution volume of the central-compartment (V(1)), inter-compartmental clearance (Q) and apparent distribution volume of the peripheral compartment (V(2)) were 0.323 L·h(-1)·kg(-1), 0.086 L/kg, 0.0957 L·h(-1)·kg(-1), and 0.0554 L/kg, respectively. The inter-individual variabilities of these parameters were 14.8%, 24.2%, fixed to 0% and 15.6%, respectively. The final PK-PD model was a sigmoid E(max) model without the Hill coefficient. In this model, a covariate, red blood cell count (RBC(*)), had a significant effect on the EC(50) value. The typical PD population values of maximum effect (E(max)), EC(50), baseline ACT value (E(0)) and the coefficient of RBC(*) on EC(50) were 318 s, 2.44 mg/L, 134 s and 1.70, respectively. The inter-individual variabilities of E(max), EC(50), and E(0) were 6.80%, 46.4%, and 4.10%, respectively. CONCLUSION: Population PK-PD models of bivalirudin in healthy young Chinese subjects have been developed, which may provide a reference for future use of bivalirudin in China.

Quantitative comparison of the efficacies and safety profiles of three first-line non-platinum chemotherapy regimens for advanced non-small cell lung cancer.

Objectives: The purpose of this study was to quantify the efficacies and safety profiles of the three first-line non-platinum chemotherapy regimens recommended in the National Comprehensive Cancer Network guidelines. Materials and Methods: The PubMed and Cochrane Library databases were searched comprehensively, and clinical trials involving patients with advanced non-small cell lung cancer treated with one of three first-line non-platinum regimens (gemcitabine combined with vinorelbine, gemcitabine combined with docetaxel, or gemcitabine alone) were included in the analysis. A parametric proportional hazard survival model was established to analyze the time course of overall survival (OS). The objective response rate (ORR) and incidence rates of grade 3-4 adverse events (AEs) were summarized using a single-arm meta-analysis with a random-effects model. Results: Seventeen studies met the inclusion criteria. Age and performance status (PS) scores were significant predictors of OS. For each 10-years increase in age, mortality risk increased by 18.5%, and the mortality risk increased by 4% for every 10% increase in the proportion of patients with a PS score of 2. After correcting for the above factors, we found that the three first-line non-platinum chemotherapy regimens did not differ based on OS or toxicity. Conclusion: There was no significant difference in OS or toxicity among the three first-line non-platinum chemotherapy regimens. Age and PS scores were significant predictors of OS, and their heterogeneity across different studies should be considered in cross-study comparisons and sample size estimations when designing clinical trials.

Race differences: modeling the pharmacodynamics of rosuvastatin in Western and Asian hypercholesterolemia patients.

AIM: To evaluate race differences in the pharmacodynamics of rosuvastatin in Western and Asian hypercholesterolemia patients using a population pharmacodynamic (PPD) model generated and validated using published clinical efficacy trials. METHODS: Published studies randomized trials with rosuvastatin treatment for at least 4 weeks in hypercholesterolemia patients were used for model building and validation. Population pharmacodynamic analyses were performed to describe the dose-response relationship with the mean values of LDL-C reduction (%) from dose-ranging trials using NONMEM software. Baseline LDL-C and race were analyzed as the potential covariates. Model robustness was evaluated using the bootstrap method and the data-splitting method, and Monte Carlo simulation was performed to assess the predictive performance of the PPD model with the mean effects from the one-dose trials. RESULTS: Of the 36 eligible trials, 14 dose-ranging trials were used in model development and 22 one-dose trials were used for model prediction. The dose-response of rosuvastatin was successfully described by a simple E(max) model with a fixed E(0), which provided a common E(max) and an approximate twofold difference in ED(50) for Westerners and Asians. The PPD model was demonstrated to be stable and predictive. CONCLUSION: The race differences in the pharmacodynamics of rosuvastatin are consistent with those observed in the pharmacokinetics of the drug, confirming that there is no significant difference in the exposure-response relationship for LDL-C reduction between Westerners and Asians. The study suggests that for a new compound with a mechanism of action similar to that of rosuvastatin, its efficacy in Western populations plus its pharmacokinetics in bridging studies in Asian populations may be used to support a registration of the new compound in Asian countries.