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。     

利伐沙班导致出血事件的群体药动学模型建立及影响因素分析

目的：建立利伐沙班出血患者群体药动学模型并对出血事件的影响因素进行分析。方法：回顾性选取93例服用利伐沙班抗凝治疗发生出血事件的患者为研究对象,收集192例次利伐沙班稳态峰谷浓度数据,以非线性混合效应模型法建立群体药动学模型并以Bayesian反馈法计算药时曲线下面积（AUC）,同时分析该群体PK模型协变量与预估药物暴露量的相关性。结果：建立的群体药动学模型可对数据进行较好拟合,协变量肾小球滤过率（e-GFR）对清除率（CL）有显著影响,最终模型为CL=77.2×EGFR/71.56^θCLcr。协变量e-GFR和年龄影响利伐沙班的估算AUC和峰浓度（C_max）数值。结论：利伐沙班出血患者群体药动学模型稳定、有效。患者肾功能和年龄影响利伐沙班出血人群体内药物暴露量。     

Reduced theophylline clearance due to hepatic congestion secondary to right heart failure - A population pharmacokinetic study

Theophylline, a beneficial drug with bronchodilatory and anti-inflammatory effects, is used for the treatment of respiratory diseases. Pulmonary (PC) and hepatic congestion (HC) are secondary to the development of left- and right-sided heart failure (HF), respectively. This study aimed to evaluate the effects of PC and HC on theophylline clearance (CL) by population pharmacokinetic (PPK) analysis with consideration of the severity of HF assessed by the New York Heart Association (NYHA) functional classification. We obtained 710 minimum steady-state concentrations from 201 Japanese bronchial asthma patients with and without HF. PPK analysis was performed by NONMEM. In the analysis, the left ventricular ejection fraction, smoking (SMK), clarithromycin (CAM), sex, and age were also considered as covariates. The final model of apparent theophylline clearance (CL/F) was as follows: CL/F (L/hr/kg) = 0.0465 × 1.40^SMK × 0.870^CAM × 0.863^{HC(+)NYHA II} × 0.634^{HC(+)NYHA III} × 0.586^{HC(−)NYHA IV} × 0.467^{HC(+)NYHA IV}. SMK is a well-known factor that markedly enhances theophylline clearance through the induction of CYP1A enzymes, while CAM has been reported to inhibit CYP3A4. The final model indicates that HF patients with HC show reduced clearance of theophylline depending on the severity of HF. In this study, no effects of PC were observed.     

Population pharmacokinetics of theophylline in adult Chinese patients with asthma and chronic obstructive pulmonary disease

Background Theophylline has a narrow therapeutic range and large interindividual variability in blood levels, so a thorough understanding of its pharmacokinetic characteristics is essential. Population pharmacokinetic (PPK) approaches could achieve it and many PPK studies of theophylline have been reported in infants. However, none was conducted in Chinese adults and none has explored the effect of CYP1A2 genotypes on the PPK characteristics of theophylline in adults. Objective To evaluate the PPK characteristics of theophylline and to assess the possible influence of covariates, including CYP1A2 genotypes, on theophylline clearance in Chinese adult patients. Setting The study is conducted at the department of respiration in Zhujiang Hospital, Guangzhou, China. Methods Theophylline concentrations were obtained from eligible patients and were measured by high performance liquid chromatography. The polymorphisms of ??3860G?>?A, ??163C?>?A, C5347T (CYP1A2*1B) and G-3113A were genotyped using a direct sequencing method. Then, CYP1A2 genotypes, age, fat-free mass (FFM) and other covariates were used to develop a PPK model by NONMEM software. Bootstrap analysis was used to asses the accuracy and prediction of the PPK model. Main outcome measure The concentration and clearance of theophylline. Results A total of 134 theophylline concentrations from 95 patients were obtained. The final model was as follows: CL/F(L/h)?=?4.530?×?(FFM/56.1)^0.75 ×?0.713^CYP1A2*1B, the inter-individual variability in clearance/bioavailability (CL/F) was 44.0%, and the residual variability was 9.8%. The final model was proved to be reliable by bootstrap analysis. Conclusion Theophylline clearance was significantly associated with FFM and CYP1A2*1B genotypes in Chinese adult patients.     

基于群体药动学的儿童奥卡西平给药方案优化和漏服药物补救方案研究

目的:建立奥卡西平在儿童群体中的药动学模型,辅助制定个体化给药方案和漏服药物后的补救方案。方法:收集124例4个月~18岁儿童癫痫患者口服奥卡西平后体内主要活性代谢产物羟基卡马西平(MHD)的药物浓度数据和临床资料,采用非线性混合效应建模法建立群体药动学(PPK)模型。应用自举法、预测值校准的直观预测检验(pc-VPC)、正态化预测分布误差检验(NPDE)评价PPK模型的预测性能。基于最终模型参数,模拟不同特征儿童患者的最佳给药方案和不同漏服场景下的补救给药方案。结果:本研究发现奥卡西平在儿童体内的药动学特征符合一级吸收和消除的一房室模型,按标准体质量70 kg成人校正的群体典型值为:吸收速率常数(K_a)=0.83 h^-1,表观分布容积(V_d/F)=16.70 L,清除率(CL/F)=1.92 L·h^-1。体质量是影响V_d/F和CL/F的显著性协变量。自举法、pc-VPC和NPDE检验显示模型预测准度高,稳定性好。模拟结果显示,按本研究推荐的维持方案和漏服后补救方案给药可提高药物浓度的达标概率,保证治疗的安全性和有效性。结论:本研究通过群体药动学研究,制定了不同体质量分层儿童患者的奥卡西平优化给药方案以及漏服药物后的补救方案,可为临床药物治疗决策提供参考。     

茶碱在老年慢性阻塞性肺疾病患者中的群体药动学

目的：建立茶碱在老年慢性阻塞性肺疾病患者中的群体药动学（PPK）模型,并获取药动学参数,为临床制定个体化给药方案提供参考。方法：收集2014年4—12月某院诊断为慢性阻塞性肺疾病应用茶碱治疗的68例老年患者的血药浓度监测数据及临床资料,运用非线性混合效应模型法（NONMEN）定量分析性别、年龄、体质量及肝肾功能等因素对药动学参数的影响,最终建立PPK模型。采用拟合优度、自举法和可视化检验对最终模型的性能进行内部验证。结果：茶碱的药动学符合一室模型,最终模型公式为：CL=θ_CL×（WT/63）^θWT×exp（η_CL）,V=θ_V×exp（η_V）,其中的协变量为体质量,模型CL和V的群体典型值分别为0.849 L·h^-1,13.7 L。拟合优度、自举法和可视化检验的评价结果表明最终模型稳定,预测结果可靠。结论：建立的PPK模型能较好地描述茶碱在老年慢性阻塞性肺疾病患者中的药动学特点,患者体质量对参数CL有显著性影响。     

Population pharmacokinetics of tacrolimus in full liver transplant patients: modelling of the post-operative clearance

Objective To investigate the population pharmacokinetics of tacrolimus in an adult liver transplant cohort using routine drug monitoring data and to identify patient characteristics that influence pharmacokinetic parameters.Methods Tacrolimus pharmacokinetics was studied in 37 adult patients using a population approach performed with NONMEM.Results A one-compartment open model with linear absorption and elimination adequately described the data. The apparent clearance (CL) was approximately zero in the immediate post-operative days (PODs) and then rapidly increased as a function of POD to reach a plateau. This was modelled as a sigmoid relationship with the characteristic parameters CL_max (plateau), TCL₅₀ (time to obtain 50% of the plateau) and gamma (coefficient of sigmoidicity). This clearance model was thought to describe the hepatic function regeneration after transplantation. Typical population estimates (percentage inter-individual variability) of CL_max, TCL₅₀, and gamma and apparent distribution volumes (V) were 36 l/h (43%), 6.3 days (33%), and 4.9 l and 1870 l (49%), respectively. The CL_max was negatively related to plasma albumin, and TCL₅₀ was positively related to aspartate amino transferase (ASAT). Bayesian estimations performed at different POD times indicated that acceptable precisions in individual pharmacokinetic predictions could be obtained after the 15th POD.Conclusion Tacrolimus clearance modelling showed that there was a large variation in individual CL estimates up to the 15th day post-surgery. After this period, the mean error resulting from the Bayesian estimation was strongly decreased and this estimation method could be applicable and should limit tacrolimus monitoring.     

High dose methotrexate population pharmacokinetics and Bayesian estimation in patients with lymphoid malignancy

The purpose of present study was to develop a population pharmacokinetic model of high dose methotrexate (HD‐MTX) infusion in patients with lymphoid malignancy, to investigate the biological and clinical covariates related to the drug distribution and elimination. It is also the purpose to propose a limited sampling strategy (LSS) for the estimation of the time above the threshold (0.2 µmol·L^?1). A total 82 patients with lymphoid malignancy were involved in the study. A pharmacokinetic model was developed using nonlinear mixed‐effect model. The influence of demographic characteristics, biological factors, and concurrent administration were investigated. The final predictive performance was validated by bootstrap and cross‐validation. Bayesian estimation was evaluated. The pharmacokinetics of HD‐MTX was described by a two‐compartment model. The pharmacokinetic parameters and the inter‐individual variability were as follows: the clearance CL, 7.45 L·h^?1 (inter‐individual variability 50.6%), the volume of the central and peripheral compartment V₁, 25.9 L (22.5%), V₂, 9.23 L (97.8%), respectively, and the intercompartmental clearance Q, 0.333 L·h^?1 (70.4%). The influence of serum creatinine on CL and weight on V₁ was retained in the final model. The protocol involved one sampling time at 44 h after the start of the infusion, allowing one to predict the time at which the MTX concentration reached the expected threshold (0.2 µmol·L^?1). Serum creatinine and weight showed significant influence on methotrexate CL and V₁, respectively. Furthermore, a Bayesian estimation based on the covariates and 44 h sample was developed, allowing prediction of the individual methotrexate pharmacokinetic parameters and the time to 0.2 µmol·L^?1. Copyright © 2009 John Wiley & Sons, Ltd.     

中国成年患者万古霉素群体药动学研究

目的:利用万古霉素治疗药物监测(TDM)数据建立群体药动学(PPK)模型,用于估算个体化药动学参数。方法:选择使用万古霉素成年患者,详细记录用药、TDM数据以及病理生理资料。采用非线性混合效应模型(NONMEM)法建立万古霉素群体药动学模型。结果:169例患者数据来源于血液科及重症监护(ICU)病房等9个科室,共获得385个血药浓度数据,其中峰浓度39个,谷浓度346个。根据文献资料及TDM数据建立二室PPK模型,万古霉素清除率(CL)、中央室(V1)及外周室(V2)分布容积、室间清除率分别为4.08 L·h-1、21.7 L、65.3 L、5.95 L·h-1,患者肌酐清除率及体重分别对CL及V2具有显著影响。根据模型预测169位患者AUC0-24h为(450.1±231.8)mg·L-1·h。结论:本研究建立的万古霉素PPK模型可以用于中国成年患者个体化药动学参数估算。     

Population Pharmacokinetics of High-Dose Methotrexate in Patients With Primary Central Nervous System Lymphoma

The intra- and inter-individual variances of methotrexate (MTX) pharmacokinetics are extremely large, and the pharmacokinetic property of MTX in patients with primary central nervous system lymphoma (PCNSL) is unestablished. A total of 701 MTX plasma concentrations from 98 patients with PCNSL under high-dose MTX therapy were used to develop the population pharmacokinetic (popPK) model of MTX by using the nonlinear mixed-effects modeling method. A 2-compartment model was employed to describe the pharmacokinetic property of MTX. In the final popPK model, inclusion of serum creatinine and body surface area significantly reduced objective function value for clearance over the base model (p <0.001), and inclusion of age significantly reduced objective function value for distribution volume of central compartment (V_c) over the base model (p <0.001). In the final popPK model, the inter-individual clearance = 6.67 × (SCR/68.1)^?0.48 × (BSA/1.75)^1.17; V_c = 24.46 × (age/57.16)^0.81. The precision of all parameters was acceptable (relative standard error <28.61%). Bootstrap and visual predictive check results indicated that the final popPK model was stable with acceptable predictive ability. The popPK model may be useful for personalized medication in PCNSL patients under high-dose MTX therapy. Further studies are warranted to confirm the results.     

大剂量甲氨蝶呤在骨肉瘤化疗中的群体药动学研究进展

大剂量(>1 g·m^-2)甲氨蝶呤(MTX)化疗方案联合甲酰四氢叶酸解救广泛应用于骨肉瘤的治疗。本文通过参阅近年来大剂量MTX在骨肉瘤治疗中的群体药动学(PPK)相关研究,对其中具有代表意义的峰浓度(C_max)、药时曲线下面积(AUC)、清除率(CL)、半衰期(t_1/2)等药动学参数与临床预后的相关性进行了文献综述,并对常见的MTX群体药动学模型以及患者年龄、性别、体质量、体表面积、肝功能、肾功能、MTX剂量、化疗药物等因素对药动学参数的影响予以了归纳总结。     

健康志愿者二甲双胍缓释片群体药动学模型的初步研究

目的 建立中国健康志愿者服用二甲双胍缓释片的群体药动学(PPK)模型,并研究不同生理因素对二甲双胍药动学参数的影响。方法 20名中国健康受试者(男性11名、女性9名),单剂量给予二甲双胍缓释片 1 000 mg,收集受试者服药后0~24 h血样标本,建立液相色谱-质谱/质谱(LC-MS/MS)方法测定人血浆二甲双胍浓度,采用非线性混合效应模型(NONMEM)建立二甲双胍的群体药动学(PPK)模型,并探讨生理因素对二甲双胍药动学的影响。结果 二甲双胍药动学符合一房室模型,清除率(CL/F)、分布容积(Vd/F)和吸收速率常数K_a分别为(95.8±7.46) L/h、(553±45.9) L及(0.596±0.070)/h。引入体重作为CL/F及Vd/F的协变量,使模型显著改善(P<0.05)。结论 NONMEM法可以用于二甲双胍药动学研究,且体重对二甲双胍清除率存在显著影响。     

Population Pharmacokinetics of the Active Metabolite of Leflunomide in Pediatric Subjects with Polyarticular Course Juvenile Rheumatoid Arthritis

Leflunomide is a pyrimidine synthesis inhibitor used in the treatment of rheumatoid arthritis. Data from two clinical studies were used to establish a population pharmacokinetic (PPK) model for the active metabolite (M1) of leflunomide in patients with juvenile rheumatoid arthritis (JRA) and determine appropriate pediatric doses. Seventy-three subjects 3–17 years of age provided 674 M1 concentrations. The PPK model was derived from nonlinear mixed-effects modeling and qualified by cross-study evaluation and predictive check. A one-compartment model with first-order input described M1 PPK well. Body weight (WT) correlated weakly with oral clearance (CL/F = 0.020·[WT/40]^0.430) and strongly with volume of distribution (V/F = 5.8·[WT/40]^0.769). Steady-state concentrations (C_ss) of M1 in JRA were compared for a variety of leflunomide dose regimens using Monte–Carlo simulation. To achieve comparable C_ss values in pediatric patients with JRA to that in adult patients, doses of leflunomide should be adjusted modestly: 10 mg/d for 10–20 kg, 15 mg/d for 20–40 kg, and 20 mg/d for > 40 kg.     

Prediction of animal clearance using naïve Bayesian classification and extended connectivity fingerprints

1. In silico models were developed for predicting high animal clearance using naïve Bayesian classification and extended connectivity fingerprints. Validation and test sets were created from a structurally diverse database of mouse, rat, dog, and monkey clearance (CL) representing approximately 20 000 unique compounds. Model performance was compared with experimental predictors used widely in drug discovery, namely in vitro intrinsic clearance (CL_i) and CL from a lower preclinical species.

2. The Bayesian model for dog CL was a better predictor than experimental rat or mouse CL. The Bayesian model for rat CL performed at least as well as mouse CL. Bayesian models outperformed mouse, rat, and monkey CL_i for predicting mouse, rat, and monkey CL, respectively.

3. These models can be used to optimize chemical libraries, direct new chemical synthesis and increase efficiency of screening cascades for lead optimization while reducing overall drug discovery cost, time and animal usage.

     

Effects of <Emphasis Type="Italic">CYP2C19</Emphasis> and <Emphasis Type="Italic">CYP2C9</Emphasis> genotypes on pharmacokinetic variability of valproic acid in Chinese epileptic patients: nonlinear mixed-effect modeling

Purpose

To evaluate the effects of CYP2C19 and CYP2C9 genotypes on the pharmacokinetic variability of valproic acid (VPA) in epileptic patients using a population pharmacokinetic (PPK) approach.

Methods

VPA concentrations were measured in 287 epileptic patients, who were genotyped for CYP2C19*2/*3 and CYP2C9*3. Patients who were on monotherapy with VPA were divided into two groups, a PPK-model group (n?=?177) and a PPK-valid group (n?=?110). The PPK parameter values for VPA were calculated in the PPK-model group by using the NONMEM software. Ultimately, a biological model and a final model were established. Each model was then used to independently predict the concentrations of the PPK-valid group to validate the two models.

Results

There was a significant effect of the CYP2C19 and CYP2C9 genotypes on the pharmacokinetic (PK) variability (P?<?0.01) in the final PPK model of CL/F. The interindividual CL was calculated according to the final model: CL/F?=?0.0951?×?(1?+?e^{0.0267?×?(3???genotype)})?+?0.0071?×?age (L/h). The coefficient of variation (CV) (omega CL/F) of the final model was 29.3%, while that of the biological model was 31.7%. Based on the genotype, the individual PK parameters can be calculated more accurately than before.

Conclusion

The CYP2C19 and CYP2C9 genotypes significantly influenced the PK variability of VPA, as quantified by NONMEM software.

     

Population Pharmacokinetics Analysis and Dosing Simulations Of Meropenem in Critically Ill Patients with Pulmonary Infection

PurposeThis study aimed to develop a population pharmacokinetic (PPK) model for meropenem to optimize dosing regimens for critically ill patients with pulmonary infection.Patients and methodsThis prospective PPK study of meropenem was conducted on a pooled dataset of 236 blood samples obtained from 48 patients with pulmonary infection in the intensive care unit. Meropenem plasma concentrations were measured by a validated high-performance liquid chromatography-tandem mass spectrometry method, and the data were analyzed using NONMEM. The effect of covariates on meropenem pharmacokinetics was investigated. The probability of target attainment (PTA) to achieve the target of 100% fT_>MIC at the proposed dosage regimens were investigated by Monte Carlo simulations.ResultsA two-compartment model adequately described the data with estimated glomerular filtration rate (eGFR) as a covariate significantly associated with the clearance (CL) from the central compartment. The typical value of CL was 7.48 L/h, with an eGFR adjustment factor of 0.0103 mL?1.73 m²/min, and the typical values of volume of the central compartment (V₁), peripheral compartmental clearance (Q), and volume of the peripheral compartment (V₂) were 15.9 L, 15.8 L/h, and 14.8 L, respectively. The goodness-of-fit plots, normalized prediction distribution error, and visual predictive checks showed good fitting and predictability of the final PPK model. When eGFR was >90 mL/min/1.73 m^2, and there was a short duration of infusion (<60min), it was difficult for the probability target attainment (PTA) to reach >90% for MIC ≥ 2. Continuous infusion and frequent administration were necessary to achieve the target of 100% fT_>MIC for critically ill patients with pulmonary infection.ConclusionTo achieve the optimal PTA, meropenem must be administered by frequent administration or continuously by an intravenous infusion. Our findings provide important information to optimize the meropenem regime in critically ill patients with pulmonary infection depending on eGFR values.     

Population pharmacokinetics of high-dose methotrexate in children with acute lymphoblastic leukaemia

OBJECTIVE: To develop and a priori validate a methotrexate population pharmacokinetic model in children with acute lymphoblastic leukaemia (ALL), receiving high-dose methotrexate followed by folinic acid rescue, identifying the covariates that could explain part of the pharmacokinetic variability of methotrexate. METHODS: The study was carried out in 49 children (aged 6 months to 17 years) who received high-dose methotrexate (3 g/m(2) per course) in long-term treatment. In an index group (37 individuals; 1236 methotrexate plasma concentrations), a population pharmacokinetic model was developed using a nonlinear mixed-effects model. The remaining patients' data (12 individuals; 278 methotrexate plasma concentrations) were used for model validation. Age, sex, total bodyweight (TBW), height, body surface area, lowest urine pH during infusion, serum creatinine, ALT, AST, folinic acid dose and length of rescue were analysed as possible covariates. The final predictive performance of the pharmacokinetic model was tested using standardised mean prediction errors. RESULTS: The final population pharmacokinetic model (two-compartmental) included only age and total bodyweight as influencing clearance (CL) and volume of distribution of central compartment (V(1)). For children aged < or =10 years: CL (L/h) = 0.287 . TBW(0.876); V(1) (L) = 0.465 . TBW, and for children aged >10 years: CL (L/h) = 0.149 . TBW; V(1) (L) = 0.437 . TBW. From the base to the final model, the inter-individual variabilities for CL and V(1) were significantly reduced in both age groups (30-50%). The coefficients of variation of the pharmacokinetic parameters were <30%, while residual and inter-occasional coefficients maintained values close to 40%. Validation of the proposed model revealed the suitability of the model. CONCLUSION: A methotrexate population pharmacokinetic model has been developed for ALL children. The proposed model could be used in Bayesian algorithms with a limited sampling strategy to estimate the systemic exposure of individual patients to methotrexate and adapt both folinic acid rescue and methotrexate dosing accordingly.     

用NONMEM法建立癫痫患者丙戊酸群体药代动力学模型

目的 建立丙戊酸(VPA)在癫痫患者中的群体药代动力学(PPK)模型,考察固定效应因素对VPA清除率(CL/F)的影响.方法 回顾性收集贵州省人民医院111名癫痫患者VPA稳态血药浓度数据及相应的人口学、合并用药及CYP2A6基因型等资料,随机将患者分成建模组(74名)及验证组(37名),使用建模组数据通过非线性混合效应模型(NONMEM)程序建立VPA的PPK模型.使用验证组数据来验证模型的准确度和精密度,比较基础模型和最终模型的平均预测误差(MPE)、平均绝对误差(MAE)、平均根方差(RMSE).结果 建立的最终模型包含了日用药剂量(DDO)及CYP2A6基因型,模型方程为:CL/F=0.363·DD00.525·1.29GENECYP2A6.最终模型有更好的精密度及准确度,基础模型MPE、MAE、RMSE值为- 10.63、14.40、22.55,最终模型相应值为-6.11、9.06、14.17.结论 本研究初步建立癫痫患者VPA的PPK模型,VPA清除率随日给药剂量的增大而增大,CYP2A6野生型(CYP2A6*1/*1)组患者较CYP2A6突变型(CYP2A6* 1/*4、CYP2A6* 4/*4)组患者有更高的VPA清除率.     

Unaltered etanercept pharmacokinetics with concurrent methotrexate in patients with rheumatoid arthritis

The purpose of this study was to evaluate the potential impact of concurrent weekly oral methotrexate administration on the pharmacokinetics of etanercept in patients with rheumatoid arthritis (RA) in a phase 3B trial. As part of a double-blind randomized trial of 682 patients with rheumatoid arthritis who received etanercept (25 mg subcutaneously twice weekly), methotrexate (weekly oral dose, median weekly dose: 20 mg), or etanercept (25 mg subcutaneously twice weekly) plus methotrexate (weekly oral dose, median weekly dose: 20 mg), serum etanercept concentrations were measured in a subset of patients. Serum samples for 98 randomly selected patients (48 receiving etanercept-alone treatment, 50 receiving etanercept plus methotrexate combination treatment) were analyzed to assess the pharmacokinetics of etanercept. A single blood sample was drawn from each patient at baseline and at the week 24 visit. Given the variable sampling time for patients in both groups, a population pharmacokinetic analysis using NONMEM was conducted for etanercept. A final covariate population pharmacokinetic model was constructed based on previously obtained etanercept data from both healthy subjects (n = 53) and patients with RA (n = 212) in 10 prior clinical trials. The predictive performance of the final model was assessed by both bootstrap and data-splitting validation approaches. The final model was then used to estimate Bayesian pharmacokinetic parameters for the patients in both treatments in the current trial. The potential effect of the concurrent administration of methotrexate on the pharmacokinetics of etanercept was examined by comparing the clearance values between 2 treatments using statistical criteria. A population 2-compartment model with first-order elimination from the central compartment and with either zero-order (intravenous administration) or first-order (subcutaneous administration) input was selected based on the data from the prior 10 etanercept clinical studies. The following pharmacokinetic parameters (typical value +/- standard error) were estimated: clearance (CL: 0.072 +/- 0.005 L/h), volume of distribution in the central compartment (V(c): 5.97 +/- 0.45 L), volume of distribution in the peripheral compartment (V(p): 2.05 +/- 0.32 L), intercompartment clearance (Q: 0.0645 +/- 0.0093 L/h), first-order absorption rate constant (k(a): 0.0282 +/- 0.0039 1/h), and absolute bioavailability for subcutaneous administration (F: 0.626 +/- 0.056). Interindividual variability of the pharmacokinetic parameters was quantified for CL (25.1%), V(c) (41.7%), k(a) (53.1%), and F (24.2%). Residual variability consisted of combined additive (11.4 ng/mL) and proportional error (49.9%). Both age (< 17 years) and body weight (< 60 kg) were found to be important covariates on CL. The results of both validation tests indicated the adequate predictive performance of the population model. Based on the bioequivalence criteria, the Bayesian-estimated clearance for patients receiving etanercept alone (mean: 0.070 L/h) was comparable to that for patients receiving a combination of etanercept and methotrexate (mean = 0.066 L/h). The pharmacokinetics of etanercept were not altered by the concurrent administration of methotrexate in patients with rheumatoid arthritis. Thus, no etanercept dose adjustment is needed for patients taking concurrent methotrexate.     

基于NONMEN法建立万古霉素新生儿群体药动学模型

目的:建立新生儿万古霉素群体药动学模型,为临床个体化给药方案提供参考。方法:回顾性收集80例静脉使用万古霉素新生儿的170个稳态血药浓度数据及临床资料,运用非线性混合效应模型(NONMEM),建立新生儿万古霉素群体药动学(PPK)模型;考察各项协变量对药动学参数的影响,对最终模型进行拟合优度、自举法(Bootstrap)及正态预测分布误差法(NPDE)验证。利用蒙特卡洛法评估患儿在不同给药方案下的血药浓度范围。结果:一室模型能较好地拟合万古霉素体内过程,清除率(CL)和表观分布容积(V)的群体典型值分别为0.297L·h-1和2.230L,表观分布容积对CL有显著影响。拟合优度、Bootstrap和NPDE表明最终模型稳定、预测结果可靠。建立不同体质量范围新生儿万古霉素初始剂量推荐表。结论:本研究建立的新生儿万古霉素PPK模型稳定可靠,可为优化新生儿给药方案提供依据。