Population pharmacokinetics of halofantrine in healthy volunteers and patients with symptomatic falciparum malaria

Aims To investigate the population pharmacokinetics of the antimalarial halofantrine (HF) in healthy volunteers and patients with symptomatic falciparum malaria. Methods Healthy volunteer data were obtained from six volunteers who received three different doses of HF (250, 500 and 1000 mg) after an overnight fast with a washout period of at least 6 weeks between doses. Patient data (n = 188) were obtained from randomised controlled trials conducted on the Thai–Burmese border in the early 1990s. They were either assigned to receive a total HF dose of 24 mg/kg (8 mg/kg every 6 h for 24 h) or 72 mg/kg (8 mg/kg every 6 to 10 h for 3 days). The population pharmacokinetics of HF were evaluated using non‐linear mixed effects modelling with a two‐compartment model with first‐order absorption. Key findings The population estimates of apparent clearance (CL), volume of compartment one (V1), distributional clearance (CLD) and volume of compartment two (V2) of HF in healthy volunteers were 2453 l/day (102 l/h), 2386 l, 716 l/day (29.8 l/h) and 2641 l, respectively. The population estimates of the PK parameters in patients were 429 l/day (17.9 l/h), 729 l, 178 l/day (7.42 l/h) and 1351 l, respectively. All PK parameters were significantly related to body weight and some were related to sex, sampling method, pre‐treatment parasite density and whether patients vomited or not. When the two datasets were analysed jointly using a maximum likelihood method, the population estimates in patients were 196 l/day (8.17 l/h), 161 l, 65 l/day (2.71 l/h) and 89 l, respectively, and the parameters were significantly related to body weight and sex. Bayesian analysis of the patient data, with a diffuse prior based on the healthy volunteer data analysis results, yielded the population estimates 354 l/day (14.8 l/h), 728 l, 162 l/day (6.75 l/h) and 1939 l, respectively. Conclusions The pharmacokinetic properties of HF in patients with malaria are affected by several demographic variables as well as other relevant covariates. Apparent differences between the healthy volunteer and the patient data analysis results are not entirely due to differences in bioavailability. For the patient data analysis, the Bayesian method was preferred, as the fitting procedure was more stable, allowing random effects to be estimated for all four dispositional parameters.     

阿托伐他汀在健康受试者中的群体药动学研究

目的建立阿托伐他汀在健康受试者中的群体药动学模型,预测其在健康人群中群体药动学特征,为临床合理用药提供依据。方法计算机检索中国期刊全文数据库(CNKI)、中文科技期刊全文数据库维普(VIP)和万方数字化期刊全文库、Pub Med电子检索系统和美国医学文摘数据库(Medline),提取阿托伐他汀的血药浓度数据,运用非线性混合效应模型(NONMEM)法构建阿托伐他汀的群体药动学模型,考察其在健康受试者体内的群体典型值特征,并以Bootstrap法进行模型验证。结果筛选出11篇文献,共纳入394例受试群体。最终得到的群体药动学参数中表观清除率(Cl/F)和表观分布容积(V/F)的群体典型值分别为255 L/h、3 180 L。结论经Bootstrap验证,阿托伐他汀在健康受试者中的群体药动学模型稳定、可靠,所得参数稳定、可信度较好。     

群体药代动力学及其在新药研究中的应用

近年来新药临床研究越来越重视群体药代动力学的应用。群体药代动力学可以定量地描述病理、生理、合并用药等多种因素对药物代谢的影响，可将PK参数中的各种变异区分开，指导用药方案的调整，从而增强对新药有效性和安全性的评价。本文对群体药代动力学的研究方法及其在新药研究中的应用进行综述．     

泛昔洛韦缓释微丸的家犬药动学研究

目的:研究泛昔洛韦(famciclovir,FCV)缓释微丸在家犬体内的药动学及相对生物利用度。方法:6条家犬随机交叉灌服FCV缓释微丸和FCV普通片375 mg后,应用HPLC法测定血药浓度并对其进行药动学和相对生物利用度研究。结果:FCV缓释微丸和普通片的达峰时间(tmax)分别为(4.80±0.84)h和(1.80±0.27)h,峰浓度(cmax)分别为(2.62±1.14)μg/mL和(4.50±0.63)μg/mL,AUC0→∞分别为(25.59±7.58)mg.h.L-1和(26.77±5.53)mg.h.L-1,平均驻留时间(MRT)分别为(9.85±2.47)h和(4.96±0.78)h,相对生物利用度为(95.09±16.64)%。结论:FCV缓释微丸具有明显的缓释特征。     

Development of a sufficient design for estimation of fluconazole pharmacokinetics in people with HIV infection

AIMS

To assess an optimal design that is sufficient to gain precise estimates of the pharmacokinetic (PK) parameters for fluconazole in people with HIV infection.

METHODS

Two studies were identified, the first in healthy volunteers and the second in HIV patients. The investigators (J.F.R. and S.B.D.) were blinded to the second study results. The healthy volunteer study was modelled and a design was found to estimate the PK parameters. The design was evaluated by comparison of the standard errors of the parameters and the predictive performance of the optimal design. The predictive performance was assessed by comparing model predictions against observed concentrations for two models. The first model, termed ‘sufficient design’, was developed from data extracted from the HIV study that corresponded to the optimal design. The second model, termed ‘HIV outcome model’, by modelling all the data from the HIV study.

RESULTS

An optimal design HIV study was developed which had considerably fewer blood samples and dosing arms compared with the actual HIV study. The optimized design performed as well as the actual HIV study in terms of parameter precision. The performance of the design, described as the precision (mg l⁻¹)² (95% confidence interval) of the predicted concentrations to the actual concentrations for the ‘sufficient design’ and ‘HIV outcome model’ models were: 0.63 (0.40, 0.87) and 0.56 (0.32, 0.79), respectively.

CONCLUSION

This study demonstrates how data from healthy volunteers can be utilized via optimal design methodology to design a successful study in the target population.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Optimal design is being employed more frequently to help reduce the number of samples taken per patient, the number of patients and number of doses to be given within a study.
• In doing this the economic and patient resources required to conduct a population pharmacokinetic or pharmacokinetic–pharmacodynamic study are reduced.

WHAT THIS STUDY ADDS

• This is the first time that healthy volunteer data (e.g. from Phase I) have been used to develop an optimal design that is to be conducted in a population with different characteristics due to disease (e.g. Phase II).

     

Population pharmacokinetics and Bayesian estimation of tacrolimus exposure in paediatric liver transplant recipients

Aims

The objectives of this study were to develop a population pharmacokinetic (PopPK) model for tacrolimus in paediatric liver transplant patients and determine optimal sampling strategies to estimate tacrolimus exposure accurately.

Methods

Twelve hour intensive pharmacokinetic profiles from 30 patients (age 0.4–18.4 years) receiving tacrolimus orally were analysed. The PopPK model explored the following covariates: weight, age, sex, type of transplant, age of liver donor, liver function tests, albumin, haematocrit, drug interactions, drug formulation and time post-transplantation. Optimal sampling strategies were developed and validated with jackknife.

Results

A two-compartment model with first-order absorption and elimination and lag time described the data. Weight was included on all pharmacokinetic parameters. Typical apparent clearance and central volume of distribution were 12.1 l h⁻¹ and 31.3 l, respectively. The PopPK approach led to the development of optimal sampling strategies, which allowed estimation of tacrolimus pharmacokinetics and area under the concentration–time curve (AUC) on the basis of practical sampling schedules (three or four sampling times within 4 h) with clinically acceptable prediction error limit. The mean bias and precision of the Bayesian vs. reference (trapezoidal) AUCs ranged from −2.8 to −1.9% and from 7.4 to 12.5%, respectively.

Conclusions

The PopPK of tacrolimus and empirical Bayesian estimates represent an accurate and convenient method to predict tacrolimus AUC_(0–12) in paediatric liver transplant recipients, despite high between-subject variability in pharmacokinetics and patient demographics. The developed optimal sampling strategies will allow the undertaking of prospective trials to define the tacrolimus AUC-based therapeutic window and dosing guidelines in this population.     

Population pharmacokinetics of theophylline during paediatric extracorporeal membrane oxygenation

AIMS: To determine the population pharmacokinetics of theophylline during extracorporeal membrane oxygenation (ECMO) from routine monitoring data. METHODS: Retrospective data were collected from 75 term neonates and children (age range 2 days to 17 years) receiving continuous infusions of aminophylline (mean rate 9.2 +/- 2.6 micro g kg-1 min-1) during ECMO. A total of 160 plasma concentrations (range 1-8 per patient), sampled at time intervals ranging from 10 h to 432 h, were included. Population PK analysis and model building were carried out using WinNonMix Professional (Version 2.0.1). Cross-validation was used to evaluate the validity and predictive accuracy of the model. RESULTS: A one-compartment model with first order elimination combined with an additive error model was found to best describe the data. Of the covariables tested, bodyweight significantly influenced clearance and volume of distribution, whereas age was an important determinant of clearance, as adjudged by the differences in the -2 x log likelihood (P < 0.005) and the residual error value. The final model parameters were estimated as: clearance (l h-1) = 0.023 x bodyweight (kg) + 0.000057 x age (days) and volume of distribution (l) = 0.57 x bodyweight (kg). The interindividual variability in clearance and volume of distribution was 38% and 40%, respectively. The residual error corresponded to a standard deviation of 3.6 mg l-1. Cross-validation revealed a median (95% confidence interval) model bias of 9.4% (2.9, 16.5%) and precision of 29.5% (24.8, 36.0%). CONCLUSIONS: The estimated clearance is significantly lower, and volume of distribution higher, than previously reported in non-ECMO patients of similar age. These differences are probably a result of the expanded circulating volume during ECMO and altered renal and hepatic physiology in this critically ill group. Large interindividual variability reflects the heterogeneous nature of patients treated on ECMO.     

Population pharmacokinetic-pharmacodynamic analysis for sugammadex-mediated reversal of rocuronium-induced neuromuscular blockade

AIMS

An integrated population pharmacokinetic–pharmacodynamic model was developed with the following aims: to simultaneously describe pharmacokinetic behaviour of sugammadex and rocuronium; to establish the pharmacokinetic–pharmacodynamic model for rocuronium-induced neuromuscular blockade and reversal by sugammadex; to evaluate covariate effects; and to explore, by simulation, typical covariate effects on reversal time.

METHODS

Data (n = 446) from eight sugammadex clinical studies covering men, women, non-Asians, Asians, paediatrics, adults and the elderly, with various degrees of renal impairment, were used. Modelling and simulation techniques based on physiological principles were applied to capture rocuronium and sugammadex pharmacokinetics and pharmacodynamics and to identify and quantify covariate effects.

RESULTS

Sugammadex pharmacokinetics were affected by renal function, bodyweight and race, and rocuronium pharmacokinetics were affected by age, renal function and race. Sevoflurane potentiated rocuronium-induced neuromuscular blockade. Posterior predictive checks and bootstrapping illustrated the accuracy and robustness of the model. External validation showed concordance between observed and predicted reversal times, but interindividual variability in reversal time was pronounced. Simulated reversal times in typical adults were 0.8, 1.5 and 1.4 min upon reversal with sugammadex 16 mg kg⁻¹ 3 min after rocuronium, sugammadex 4 mg kg⁻¹ during deep neuromuscular blockade and sugammadex 2 mg kg⁻¹ during moderate blockade, respectively. Simulations indicated that reversal times were faster in paediatric patients and slightly slower in elderly patients compared with adults. Renal function did not affect reversal time.

CONCLUSIONS

Simulations of the therapeutic dosing regimens demonstrated limited impact of age, renal function and sevoflurane use, as predicted reversal time in typical subjects was always <2 min.     

Population pharmacokinetics of abacavir in infants,toddlers and children

Aims

To characterize the pharmacokinetics of abacavir in infants, toddlers and children and to assess the influence of covariates on drug disposition across these populations.

Methods

Abacavir concentration data from three clinical studies in human immunodeficiency virus-infected children (n = 69) were used for model building. The children received either a weight-normalized dose of 16 mg kg⁻¹ day⁻¹ or the World Health Organization recommended dose based on weight bands. A population pharmacokinetic analysis was performed using nonlinear mixed effects modelling VI. The influence of age, gender, bodyweight and formulation was evaluated. The final model was selected according to graphical and statistical criteria.

Results

A two-compartmental model with first-order absorption and first-order elimination best described the pharmacokinetics of abacavir. Bodyweight was identified as significant covariate influencing the apparent oral clearance and volume of distribution. Predicted steady-state maximal plasma concentration and area under the concentration–time curve from 0 to 12 h of the standard twice daily regimen were 2.5 mg l⁻¹ and 6.1 mg h l⁻¹ for toddlers and infants, and 3.6 mg l⁻¹ and 8.7 mg h l⁻¹ for children, respectively. Model-based predictions showed that equivalent systemic exposure was achieved after once and twice daily dosing regimens. There were no pharmacokinetic differences between the two formulations (tablet and solution). The model demonstrated good predictive performance for dosing prediction in individual patients and, as such, can be used to support therapeutic drug monitoring in conjunction with sparse sampling.

Conclusions

The disposition of abacavir in children appears to be affected only by differences in size, irrespective of the patient''s age. Maturation processes of abacavir metabolism in younger infants should be evaluated in further studies to demonstrate the potential impact of ontogeny.     

Population pharmacokinetic analysis and optimization of the experimental design for mizolastine solution in children

Mizolastine is a second generation antihistamine agent approved in Europe for the treatment of allergic rhinitis and skin conditions for which SanofiSynthélabo is developing a pediatric solution. Our objective was to design the population pharmacokinetic (PK) study of mizolastine pediatric solution in children. A bioavailability study of this solution compared to the marketed tablet was performed in 18 young volunteers. These PK data were analyzed by nonlinear regression using a two-compartment open model with zero-order absorption. From the estimated parameters, we designed population PK studies in two groups of children: 6 to 12 years and 2 to 6 years, respectively. To compare several population designs and to derive the optimal ones, we used the determinant of the Fisher information matrix of the population characteristics using a first-order expansion of the model. We have evaluated a reference population design with 10 samples (from 0.25 to 36 hr after drug intake) per child in 6 children, which could not be implemented in practice for ethical reasons. We then derived optimal population designs with 1, 2, 3, 4, or 5 samples per child and a total of 60 samples. Finally, the designs that were implemented in the population PK study were compromise population designs with 60 samples; one defined for 20 children 6 to 12 years old , and one with 24 children 2 to 6 years. In the older group, the population design involved 8 children with a catheter from which 6 samples at time 0.25, 0.5, 0.75, 2, 3, and 6 hr after drug intake are collected, and 12 children with only one sample at time 8, 12, 24, or 36 hr. In the younger group, the population design involved 15 children with a catheter who are divided in three groups with four samples at different times from 0.25 to 6 hr after drug intake, and 12 children with only one sample at time 8, 12, 18, or 24 hr. The expected average increase of variances of these designs compared to the reference design were 1.6 and 1.8 for the older and younger group, respectively, which was decided to be acceptable. Better population designs would have involved three groups of children with five samples per child but could not be implemented in practice. The data of the PK study in children 6 to 12 years were available and were analyzed using NONMEM. A total of 53 concentrations were obtained in 18 children. The same two-compartment model with zero-order absorption was used. The interindividual variability in children was small. The estimated population parameters in children 6 to 12 years, were 0.28 L/kg for V_c/F, 0.10 L/hr per kg for CL/F, 0.53 hr^–1 for ₁, 0.076 hr^–1 for ₂ , and 0.49 hr for T _abs . These values were close to the median values observed in young volunteers when standardized to 70 kg; notably, CL/F in L/hr per kg was similar, so that a dose of 0.15 mg/kg o.d. for mizolastine pediatric solution should give an equivalent area under the curve to a 10 mg o.d. tablet in adults.     

Population pharmacokinetics of melphalan in paediatric blood or marrow transplant recipients

AIM: To develop a population pharmacokinetic model for melphalan in children with malignant diseases and to evaluate limited sampling strategies for melphalan. METHODS: Melphalan concentration data following a single intravenous dose were collected from 59 children with malignant diseases aged between 0.3 and 18 years. The data were split into two sets: the model development dataset (39 children, 571 concentration observations) and the model validation dataset (20 children, 277 concentration observations). Population pharmacokinetic modelling was performed with the NONMEM software. Stepwise multiple linear regression was used to develop a limited sampling model for melphalan. RESULTS: A two-compartment model was fitted to the concentration-vs.-time data. The following covariate population pharmacokinetic models were obtained: (i) Clearance (l h(-1)) = 0.34.WT - 3.17.CPT + 0.0377.GFR, where WT = weight (kg), CPT = prior carboplatin therapy (0 = no, 1 = yes), and GFR = glomerular filtration rate (ml min(-1) 1.73 m(-2)); (ii) Volume of distribution (l) = 1.12 + 0.178.WT. Interpatient variability (coefficient of variation) was 27.3% for clearance and 33.8% for volume of distribution. There was insignificant bias and imprecision between observed and model-predicted melphalan concentrations in the validation dataset. A three-sample limited sampling model was developed which adequately predicted the area under the concentration-time curve (AUC) in the development and validation datasets. CONCLUSIONS: A population pharmacokinetic model for melphalan has been developed and validated and may now be used in conjunction with pharmacodynamic data to develop safe and effective dosing guidelines in children with malignant diseases.     

Population pharmacokinetics analysis of intravenous busulfan in Chinese patients undergoing hematopoietic stem cell transplantation

There are several reports describing population pharmacokinetic (popPK) models of busulfan (BU). However, limited information is available in Chinese hematopoietic stem cell transplantation (HSCT) patients. The present study aimed to establish a popPK model of intravenous BU in Chinese HSCT patients for individualized drug therapy. The popPK model of BU was developed from a total of 284 concentration–time points from 53 patients. The effects of demographic and biochemical covariates were investigated by nonlinear mixed effect model (NONMEM) software. Plots, visual predictive check (VPC), bootstrap and normalized prediction distribution error (NPDE) were performed to determine the stability and the reliability of the final model. A one‐compartment model with first‐order elimination process was confirmed as the final structural model for BU. For a typical patient whose body surface area (BSA) is 1.7 m², the population typical values of CL and Vd were 11.86 L/h, and 48.2 L, respectively. The result suggested BSA showed significant influence on CL and Vd (P<.001). Plots revealed the final model was performing a goodness fit. The steady rate verified by bootstrap was 100%, relative deviation was less than 4.00%, estimated value of final model was in the 95% confidence interval (CI). The VPC results showed the observed values were almost all positioned within the 5th and 95th CIs. The mean and variance of the NPDE were 0.0363 (Wilcoxon signed‐rank test, 0.298) and 0.877 (Fisher variance test, 0.134; SW test of normality, 0.108), respectively. The global adjusted P value was 0.305, which indicated that the prediction of the BU popPK model was adequate. A physician‐friendly Microsoft Excel‐base tool was implemented using the final popPK model for designing individualized dosing regimens.     

重组葡激酶群体药动学研究

目的:应用非线性混合效应模型(NONMEM)法研究重组葡激酶(r-SAK)的群体药动学.方法:建立双抗体酶联免疫吸附法(ELiSA)测定r-SAK的血浆药物浓度,应用NONMEM法进行模型优化,确定r.SAK的药动学模型和统计学模型,估算群体药动学参数和个体间、个体内变异,并进行统计分析.结果:建立了r-SAK的特异性浓度测定方法.r-SAK符合二房室一级消除模型,体重(WET)和肌酐对k21有显著性影响,方程为k21=θ(3)×WETθ(5),最终估算结果:k=0.19h-1,k12=1.93h-1,k21=1.87×10-4×WET11.8h-1,V=13.2L.计算所有参数的SE(Standard error)和95%CI(Confidence interva1)评价参数估算方法的优劣.结论:应用NONMEM法估算出的群体药动学参数结果可全面给出药物的药动学参数和变异,为r-SAK的安全性和有效性研究提供了丰富的依据.     

Population pharmacokinetics of tamsulosin hydrochloride in paediatric patients with neuropathic and non-neuropathic bladder

AIMS

The main objective of this study was to characterize the population pharmacokinetics of tamsulosin hydrochloride (HCl) in paediatric patients with neuropathic and non-neuropathic bladder. A secondary objective was to compare the pharmacokinetics in paediatric patients and adults.

METHODS

Tamsulosin HCl plasma concentrations in 1082 plasma samples from 189 paediatric patients (age range 2–16 years) were analyzed with NONMEM, applying a one compartment model with first-order absorption. Based on the principles of allometry, body weight was incorporated in the base model, along with fixed allometric exponents. Covariate analysis was performed by means of a stepwise forward inclusion and backward elimination procedure. Simulations based on the final model were used to compare the pharmacokinetics with those in adults.

RESULTS

Beside the priori-implemented body weight, only α₁-acid glycoprotein had an effect on both apparent clearance and apparent volume of distribution. No other investigated covariates, including gender, age, race, patient population and concomitant therapy with anti-cholinergics, significantly affected the pharmacokinetics of tamsulosin HCl (P < 0.001). The results of simulations indicated that the exposure in 12.5 kg paediatric patients was 3.5–4.3 fold higher than that in 70.0 kg adults. After a weight-based dose administration, the exposure in paediatric patients was comparable with that in healthy adults.

CONCLUSIONS

A population pharmacokinetic model of tamsulosin HCl in paediatric patients was established and it described the data well. There was no major difference in the pharmacokinetics of tamsulosin HCl between paediatric patients (age range 2–16 years) and adults when the effect of body weight was taken into consideration.     

Population pharmacokinetics of tacrolimus in Asian paediatric liver transplant patients

AIMS: The purpose of this study was to describe the population pharmacokinetics of intravenous and oral tacrolimus (FK506) in 20 Asian paediatric patients, aged 1-14 years, following liver transplantation and to identify possible relationships between clinical covariates and population parameter estimates. METHODS: Details of drug dosage histories, sampling times and concentrations were collected retrospectively from routine therapeutic drug monitoring data accumulated for at least 4 days after surgery. Before analysis, patients were randomly allocated to either the population data set (n = 16) or a validation data set (n = 4). The population data set was comprised of 771 concentration measurements of patients admitted over the last 3 years. Population modelling using the nonlinear mixed-effects model (NONMEM) program was performed on the population data set, using a one-compartment model with first-order absorption and elimination. Population average parameter estimates of clearance (CL), volume of distribution (V) and oral bioavailability (F) were sought; a number of clinical and demographic variables were tested for their influence on these parameters. RESULTS: The final optimal population models related clearance to age, volume of distribution to body surface area and bioavailability to body weight and total bilirubin concentration. Predictive performance of this model evaluated using the validation data set, which comprised 86 concentrations, showed insignificant bias between observed and model-predicted blood tacrolimus concentrations. A final analysis performed in all 20 patients identified the following relationships: CL (l h-1) = 1.46 *[1 + 0. 339 * (AGE (years) -2.25)]; V (l) = 39.1 *[1 + 4.57 * (BSA (m2)-0. 49)]; F = 0.197 *[1 + 0.0887 * (WT (kg) -11.4)] and F = 0.197 *[1 + 0.0887 * (WT (kg) -11.4)] * [1.61], if the total bilirubin > or = 200 micromol l-1. The interpatient variabilities (CV%) in CL, V and F were 33.5%, 33.0% and 24.1%, respectively. The intrapatient variability (s.d.) among observed and model-predicted blood concentrations was 5.79 ng ml-1. CONCLUSIONS: In this study, the estimates of the pharmacokinetic parameters of tacrolimus agreed with those obtained from conventional pharmacokinetic studies. It also identified significant relationships in Asian paediatric liver transplant patients between the pharmacokinetics of tacrolimus and developmental characteristics of the patients.     

Population pharmacokinetics of epinastine, a histamine H1 receptor antagonist, in adults and children

AIMS: Our objective was to develop a population pharmacokinetic (PPK) model for epinastine, a histamine H(1) receptor antagonist, in adults and children and to obtain pharmacokinetic information to support dosing recommendations in children. METHODS: A total of 1510 plasma samples were collected from 62 healthy adult volunteers and 62 paediatric atopic dermatitis patients. The data were analysed using the NONMEM program according to a two-compartment model with first-order absorption. In addition, the final PPK model was evaluated by means of bootstrapping resampling. RESULTS: The oral clearance (CL/F) was found to be associated with body weight, formulation and food status. The volume of distribution of the central compartment (V(1)/F) was related to body weight and food status. An absorption lag time was apparent in fed subjects. On the other hand, other covariates (formulation on V(1)/F, volume of distribution of the peripheral compartment (V(2)/F), first-order absorption rate constant (Ka) and absorption lag time (ALAG); food status on V(2)/F and Ka; body weight on V(2)/F) were not statistically significant. No effect of age on CL/F, V(1)/F or V(2)/F was found. The mean parameter estimates obtained with an additional 200 bootstrap replicates of data were within 90-117% of those obtained with the original data set. These results suggest that the pharmacokinetics of epinastine are similar in adults and in children, except for the effect of the difference of body weight. The result of the application of the PPK model to the clinical trial in paediatric patients, in which dosage was determined based on the body weight (from 14 kg to less than 24 kg; 10 mg dose, 24 kg or more; 20 mg dose), showed that the C(max) and AUC (25.6 +/- 6.9 ng ml(-1) and 246.8 +/- 68.2 ng h ml(-1)) were almost same levels with those of adults after administration of 20 mg (26.9 +/- 9.1 ng ml(-1) and 281.6 +/- 90.5 ng h ml(-1)). CONCLUSIONS: A PPK model for epinastine was established and further evaluation by bootstrapping indicated that this model is stable. The model shows that, if dosage is adjusted based on the body weight, the epinastine exposure in paediatric patients is similar to that in adults.     

成年患者替考拉宁群体药动学研究

目的：构建中国成年患者替考拉宁（teicoplanin,TEC）群体药动学（population pharmacokinetics,PPK）模型,探讨TEC药动学参数的影响因素。方法：收集患者的用药信息、血药总浓度、性别、年龄、血清肌酐水平等信息,采用非线性混合效应模型法（nonlinear mixed effect model,NONMEM）建立替考拉宁PPK模型。用图形法、非参数自举法（bootstrap）、正态化预测分布误差法（normalized predictive distribution error,NPDE）进行模型评价。结果：共收集111例成年患者的149个替考拉宁血浆总浓度数据,建立了替考拉宁的一房室PPK模型：CL （L·h^-1）=1.26×（eGFR/82）^0.431,V（L）=83.1,协变量分析显示肌酐清除率（CKD-EPI公式）是影响替考拉宁清除率的重要因素,未发现影响替考拉宁表观分布容积的因素。经验证,最终模型具有良好的拟合优度、稳健率及预测性能。结论：临床可根据患者肌酐清除率（CKD-EPI公式）制定个体化给药方案。     

丙戊酸钠在癫痫患者中的群体药动学

目的建立丙戊酸钠在癫痫患者治疗中的群体药动学模型,为临床个体化给药提供参考。方法收集我院门诊60名癫痫患者丙戊酸钠稳态血药浓度监测数据和相应的人口学数据,应用非线性混合效应模型(non linearm ixed-effectmodel,NONMEM)程序对收集的数据进行分析,建立群体药动学模型。结果建立了癫痫患者口服丙戊酸钠群体药代动力学模型:CL/F=0.959×1.04x,(x=0,1),V/F=1.35,ka=2.38 h-1,说明丙戊酸的清除率与患者性别相关,即男性患者的清除率大于女性。结论初步建立癫痫患者口服丙戊酸钠群体药动学模型,为丙戊酸钠个体化用药提供理论基础。     

中国健康人群西布曲明的群体药动学模型的建立

目的建立中国人群中西布曲明的群体药动学模型。方法 20例男性健康志愿者口服10 mg西布曲明,于服药后0～24 h采集13个采样点采血,采用已验证的HPLC法测定血药浓度。采用非线性混合效应模型（NONMEM）进行群体药动学分析,估算药动学参数。以直观预测检验（Visual predictive check,VPC）和正态预测分布误差（Normalized predictive distribution error,NPDE）,Bootstrap法进行模型性能评估。结果以有吸收时滞的一级吸收和消除的二房室模型为西布曲明的基础药动学模型。协变量筛选未见体重、年龄可显著影响模型参数。残差模型选择指数模型。西布曲明群体药动学参数V1,V2,CL,Q,Ka,Tlag的典型值分别为：7.85 L、2.03 L、1.08 L/h、0.289 L/h、1.95/h、0.187 h;个体间变异分别为42.8%、48.2%、38.5%、27.1%、56.8%和17.8%。Bootstrape、拟合优度、VPC和NPDE的评价结果均表明模型稳定,预测结果可靠。结论用非线性混合效应模型法建立的中国人群中西布曲明的群体药动学模型,结果稳定。