NONMEM法估算中国癫痫患者卡马西平的清除率

目的　考察中国癫痫患者卡马西平的群体药动学参数。方法　癫痫病例来自上海、北京两地 4所医院 ,采集服用卡马西平的 5 92例患者的稳态血药浓度 (n =70 3)。NONMEM程序估算分析时 ,采用一级吸收和消除的药动学模型并固定吸收速率、生物利用度和表观分布体积参数。结果　体重 (TBW )、剂量 (Dose)、合用丙戊酸钠 (VPA)且其日剂量大于 2 0mg·kg-1·d-1、苯妥英 (PHT)、苯巴比妥 (PB)和年龄大于 6 5岁的老年人 (ELDER)均为卡马西平清除率(CL)的影响因素。性别、合用氯硝西泮、妥吡酯不改变卡马西平的清除率。最终模型为 :CL(CL/F) (L/h) =1 32·Dose(g·kg-1·d-1) 0 42 1·TBW (kg) 0 .691·1 2 0 VPA·1 4 3PHT·1 14 PB·0 836 ELDER。讨论　根据中国癫痫患者的群体药动学模型 ,结合患者服用的剂量、体重和合并用药可估算其清除率 ,制定给药方案     

Effect of esomeprazole on the pharmacokinetics of carbamazepine

Objective:

Present study was carried out to evaluate effect of esomeprazole on the pharmacokinetics of carbamazepine in rabbits.

Materials and Methods:

Study was conducted at Department of Pharmacology, Postgraduate Institute of Medical Education and Research from March to October 2007. In a parallel design study, carbamazepine 40 mg/kg/day was given orally for 14 days. On day 15, blood samples were taken at various time intervals between 0 and 24 hours. In esomeprazole group, carbamazepine was administered for 14 days as above. On day 8, esomeprazole 2.8 mg/kg/day along with carbamazepine 40 mg/kg/day was administered till 14 days and blood samples were drawn on 15^th day. Plasma levels of carbamazepine were assayed by high-performance liquid chromatography and pharmacokinetic parameters were calculated.

Results:

In all groups there was a decrease in the AUC_0-24 when carbamazepine was coadministered with esomeprazole. The decrease in AUC_0-24 (22.78 ± 4.71 to 10.46 ± 2.29), C_max (2.76 ± 0.77 to 1.412±1.08), T_max (2.83 ± 0.17 to 3 ± 0.40) was statistically significant (P < 0.05) when esomeprazole was given along with carbamazepine. Additionally, absorption and elimination constant were also altered significantly.

Conclusions:

These results suggest that concomitant use of esomeprazole alters the pharmacokinetics of carbamazepine. Confirmation of these results in human studies will warrant changes in carbamazepine dose or frequency when esomeprazole is coadministered.     

Determination of phenobarbitone population clearance values for South African children

Non-linear Mixed Effects Modelling (NONMEM) was used to estimate phenobarbitone population clearance values for South African children, using 52 serum levels gathered from 32 patients during their routine care. NONMEM was also used to evaluate the influence of fixed effects such as weight, age and concomitant medication. The final model describing phenobarbitone clearance was CL=[Exp(0.0288 Wt–2.53)] M, where CL=clearance (l·h^–1), Exp=the base of the natural logarithm, Wt=patient weight (kg) and M=a scaling factor for concomitant medication with a value of 1 for patients on phenobarbitone monotherapy, 0.62 for those receiving concomitant valproate and 0.87 for those patients receiving concomitant carbamazepine or phenytoin. Mean (95% confidence interval) phenobarbitone clearance values were 7.6 ml·h^–1·kg^–1 (6.2, 9.0 ml·h^–1·kg^–1) for the monotherapy group, 5.0 ml·h^–1·kg^–1 (4.0, 6.0 ml·h^–1·kg^–1) in the presence of concomitant valproate and 6.8 ml·h^–1·kg^–1 (5.6, 8.0 ml·h^–1·kg^–1) in the presence of concomitant carbamazepine or phenytoin. These values are similar to those previously reported from both traditional and NONMEM pharmacokinetic studies.     

Effect of single- and multiple-dose carbamazepine on the pharmacokinetics of diphenylhydantoin

Summary A three-phase trial has been done in 11 volunteers. They were given 600 mg phenytoin (Dilantin capsules) in each phase after an overnight fast. In the first study, phenytoin was given alone. In the second phase 400 mg carbamazepine (CBZ) was given at the same time as the phenytoin, and in the third part, 200 mg CBZ t. d. s. was given for one week prior to the phenytoin. Blood samples were taken for 72 h in each phase. Plasma levels of phenytoin and CBZ were determined by HPLC, and plasma protein binding was determined by equilibrium dialysis.The unbound fraction of phenytoin was 0.082, 0.085, and 0.077 in the control, single-dose CBZ, multi-dose CBZ phases, respectively. Single and multiple doses of CBZ decreased the plasma level of phenytoin. The 72-h AUC of phenytoin was 276, 237, and 176 mg h·l^–1 in the 3 phases, respectively, and the 72-h AUC of unbound phenytoin was 22.8, 20.5, 13.0 mg h·l^–1. The AUC of phenytoin (unbound and total) after multiple doses of CBZ was significantly lower than in the other two phases. The apparent volume of distribution (V_z/f) was 89.9, 110.3, and 121.3 l in the 3 phases, respectively.Through pharmacokinetic analyses, the decreased AUC and increased V_z/f were attributed to decreased bioavailability of phenytoin when CBZ was co-administered.     

非线性混合效应模型法估算癫痫患者卡马西平的群体药动学参数

目的:建立癫痫患者卡马西平(CBZ)的群体药动学(PPK)模型。方法:采集我院服用CBZ的270例门诊癫痫患者的稳态血药浓度数据(共316个样本)以及患者相关资料数据。应用非线性混合效应模型(NONMEM)法估算癫痫患者CBZ的PPK参数值,建立PPK模型。并运用自举法(Bootstrap)验证模型的可靠性。结果:年龄(AGE)、每日服药剂量(DKG)、体质量(BW)均为CBZ清除率(CL)的影响因素。最终模型:当AGE≤14岁时,CL(L/h)=[2.55+0.013×(AGE-15)]×(DKG/0.011)0.443×(BW/40)0.392;AGE>14岁时,CL(L/h)=2.55×(DKG/0.011)0.443×(BW/40)0.392。表观分布容积(Vd)=85L。经Bootstrap法验证,本模型稳定、可靠。结论:用NONMEM软件成功建立我院癫痫患者服用CBZ的PPK模型。根据本院癫痫患者的PPK模型,结合患者DKG、BW和合并用药可估算其CL,优化临床个体化用药方案。     

NONMEM法分析艾普拉唑肠溶片在中国人体内的群体药动学

目的:考察中国人口服艾普拉的群体药动学特征。方法:70例胃溃疡或反流患者口服艾普拉唑肠溶片后,静脉采血,以液-质联用(LC-MS/MS)法测定艾普拉唑血浆浓度,用非线性混合效应模型(NONMEM)程序分析中国人艾普拉唑群体药动学特征。结果:成功建立了威布尔函数模型并获得相应的群体药动学模型参数,表观清除率(CL/F)为2.74 L/h,表观分布容积(V/F)为12.6 L,吸收速率常数(Ka)为0.361,形状因子(Gama)为2.19,性别对CL/F的影响(GEN CL)为0.881。结论:本试验所建立的模型拟合度高。性别对CL/F的影响显著;体质量、身高、丙氨酸氨基转移酶、天冬氨酸氨基转移酶、血清肌酐及基础疾病(溃疡和反流)均不影响艾普拉唑在目标适应证受试者体内的药动学行为。     

卡马西平在癫痫患儿中的群体药动学研究

目的:研究卡马西平(CBZ)在癫痫患儿中的群体药动学。方法:回顾性收集我院119例服用CBZ的门诊癫痫患儿的稳态血药浓度(n=122)。用非线性混合效应模型(NONMEM)法进行数据分析,定量考察年龄、性别、体重、日剂量和合用其他抗癫痫药对CBZ清除率的影响。采用一房室开放模型和一级吸收和消除的药动学模型,按照固定吸收速率常数文献值,最终求算CBZ的清除率。结果:最终拟合群体药动学模型为:CL=0.593·(体重/28.5)0.63·日剂量0.569。性别、合用丙戊酸钠不影响CBZ的清除率。结论:用NONMEM法估算CBZ的清除率和推荐剂量,可为临床制订个体化给药方案、提高疗效、降低药物的毒副作用提供依据。     

儿童卡马西平血药浓度与临床评价

目的：探讨癫痫患儿卡马西平血药浓度与服药剂量、年龄、疗效的相关性。方法：采用荧光偏振免疫分析法测定儿童卡马西平血药浓度1547例/次,将病人的药历等详细资料逐一录入数据库,利用SPSS10．0软件辅助分析。结果：不同年龄儿童卡马西平血药浓度与剂量和疗效之间存在相关,体内的代谢过程有一定的个体差异。结论：治疗药物监测有助于个体化给药、鉴别诊断和了解病人的依从性,以便更好地发挥抗癫痫药的作用,卡马西平抗癫治疗的血药浓度不必过分强调有效浓度低限。     

肾移植患者西罗莫司的群体药动学研究

目的:建立中国肾移植患者西罗莫司的群体药动学模型,为实施个体化用药提供理论支持。方法:选择47名肾移植术后采用西罗莫司+泼尼松+环孢素或他克莫司或霉酚酸酯(MMF)三联免疫抑制治疗的患者为研究对象,回顾性收集47名患者服药后的101个西罗莫司稳态血药浓度及相应的试验室检查数据,运用Winnonmix药动学软件,采用非线性混合效应模型(NONMEM)分析体重、年龄、性别、给药剂量、合并用药、肌酐清除率等对药动学参数的影响。最终模型的验证采用Jackknife法进行内部验证。结果:西罗莫司符合无滞后时间的一级消除动力学一室模型。固定效应结果量子,合用MMF和体重可影响药物清除率。最终模型公式为:CL/F(L·h-1)=11.01×0.14MMF+0.089×W。CL/F和Vd/F的群体典型值分别是11.01L·h-1和3616L,个体间变异分别为62.82%和85.07%。观测值和预测值间的残差(SD)和相关系数(r)分别是1.0ng·mL-1和0.94。结论:所建立的群体药动学模型能较好地估算服用西罗莫司的肾移植患者的个体及群体药动学参数,对指导临床个体化用药具有重要意义。     

Influence of diosmin on the metabolism and disposition of carbamazepine in healthy subjects

1.?Carbamazepine (CBZ) is an antiepileptic drug with narrow therapeutic window and administration in humans receiving long-term therapy with diosmin (DSN) may occur, which leads to CYP3A4-mediated drug interactions. The purpose of the present study was to assess the influence of DSN on the metabolism and pharmacokinetics of CBZ in healthy volunteers.

2.?An open-label, sequential, two-period study was conducted in 12 healthy male volunteers. A single dose of DSN 500?mg was administered once daily for 10 days during treatment phase. A single dose of CBZ 200?mg was administered during control and after treatment phases under fasting conditions. The blood samples were collected after CBZ dosing at predetermined time intervals and analyzed by LC-MS/MS.

3.?Treatment with DSN significantly enhanced the maximum plasma concentration (C_max)_, area under the curve (AUC), half-life (t_1/2) and significantly decreased the apparent oral clearance (CL/F) and elimination rate constant (K_el) of CBZ. On the other hand, treatment with DSN significantly decreased the C_max and AUC of carbamazepine 10, 11-epoxide (CBZE). Furthermore, treatment with DSN significantly decreased the metabolite to parent ratios of C_max and AUC, indicating the reduced metabolism of CBZ to CBZE.

4.?The results suggest that the altered CYP3A4 enzyme activity and pharmacokinetics of CBZ might be attributed to DSN-mediated inhibition of CYP3A4 enzyme, which indicates pharmacokinetic interaction present between DSN and CBZ. Therefore, we conclude that DSN has an inhibiting effect on the metabolism and disposition of CBZ.     

Distribution and elimination kinetics of carbamazepine in man

Summary Carbamazepine (2.7–3 mg/kg) was administered orally as an alcoholic solution (50% v/v) to eight healthy volunteers. Two of the subjects were also given 50 mg and 100 mg of carbamazepine in alcoholic solution and 200 mg as a tablet. Plasma concentrations, which were analysed by mass fragmentography, reached a maximum 1 – 7 hours after dosing, and then declined monoexponentially with half-lives ranging from 24 to 46 hours. The half-lives were independent of dose. The apparent distribution volume ranged from 0.79 to 1.40 l/kg. It was found that 72% of carbamazepine was bound to plasma proteins with little interindividual variation, and this was not influenced by the presence of diphenylhydantoin or phenobarbital in therapeutic concentrations. The pharmacokinetic parameters calculated from single oral doses were used to predict the steady-state plasma concentration expected after treatment with multiple doses of 200 mg three times daily. The predicted steady-state concentration was 2 – 3 times higher than that reported in patients undergoing chronic treatment with carbamazepine at this dose level, i.e. the pharmacokinetics of carbamazepine apparently change during multiple dosing.Dedicated to the memory of Balzar Alexandersson, MD.Medical Research Council (U.K.) Travelling Fellow     

Population pharmacokinetics of arbekacin in burn patients

The aim of this study was to estimate the pharmacokinetics (PK) of arbekacin in burn patients using a population–PK approach. Therapeutic drug monitoring data consisting of 126 plasma concentrations (including 17 values that were below the quantitation limit) from 47 burn patients were retrospectively analyzed using a mixed effect method (NONMEM, ver. 6.0). Covariates, such as burn index, age, sex, among others, were tested on the basic one-compartment model. In the basic model, positive correlations of body weight (WT) and creatinine clearance (CLcr) on total clearance (CL) and volume of distributions (V) were assumed. In the final model, V increased with burn index (BI). The final model was: ;. Between-subject variability in terms of CL and V were 35 and 39%, respectively. The CL of our burn patients was significantly greater than that reported in unburned patients, and V increased proportionally with increasing BI.     

术中植入缓释氟尿嘧啶在直肠癌患者中的群体药动学研究

目的:建立并考察直肠癌患者术中植入氟尿嘧啶的群体药动学（PPK）模型,为直肠癌患者的临床用药提供个体化指导。方法:通过完整的药动学（PK）采样法收集20名直肠癌患者的血药浓度120个。一室模型为基础,通过使用非线性效应模型拟合法（NONMEM）建立群体药动学模型,考察固定效应（身高、体质量、年龄、性别、肝肾功能、联合用药等）对氟尿嘧啶PK参数的影响。结果:氟尿嘧啶植入剂PPK参数为:Ke（0.005 44±0.002 89）h^-1,Ka（0.748±0.602）h^-1,V/F（1.06±0.343）L·kg^-1,Ke（0.005 7±0.541）h^-1,CL/F（262±0.194）L·kg^-1。模拟1 000个受试者的数据,结果显示血药浓度的90%可信区间基本涵盖实测值,证实了模拟结果的可靠性。结论:本研究成功建立氟尿嘧啶植入剂的群体药动学模型,可以估算个体药动学参数预测血药浓度,满足优化个体化给药的需要。     

A population pharmacokinetic model for cefuroxime using cystatin C as a marker of renal function

AIMS: Since cefuroxime mainly is excreted by renal filtration, dosing is currently based on serum creatinine (Scr) or creatinine clearance (CLcr). However, it has been suggested that cystatin C (CysC) is superior to Scr as a marker of renal function. The aim of this prospective study was to develop a population model that describes the pharmacokinetics of cefuroxime and to investigate the usefulness of CysC as a covariate of the model parameters. METHODS: Ninety-seven patients were studied (CLcr range 6.5-115 ml min(-1)). Blood samples (n = 407) for the determination of cefuroxime were withdrawn according to a sparse data sampling schedule and analysed by liquid chromatography mass spectrometry. The population analysis was performed in NONMEM. RESULTS: A two-compartment model described the data well. The biomarkers Scr, CLcr and CysC were evaluated as covariates on clearance (CL). The model that included CysC generated the best fit. In the final population model CL was a function of CysC and body weight, whereas V(1) was only a function of body weight. Final parameter estimates (relative standard errors) were 6.00 (3.2%) l h(-1), 11.4 (5.3%) l and 5.11 (11%) l for CL, V(1) and V(2), respectively. CONCLUSIONS: Based on the results of the present study, and because CysC is practical to use in the clinic, it is suggested that individual dosing of cefuroxime may be based on CysC rather than on Scr or CLcr. Furthermore, our final population model may be useful as a tool when designing new dosing schedules for cefuroxime.     

Population pharmacokinetics of mefloquine in military personnel for prophylaxis against malaria infection during field deployment

Objective The purpose of this study was to determine the population pharmacokinetics of mefloquine in healthy military personnel during prophylaxis for malaria infections. Methods The subjects were 1,111 Australian soldiers participating in two studies: a randomised double-blinded study (group A, 161 subjects) and an open-label study (group B, 950 subjects). Following a loading dose (250 mg mefloquine base daily, 3 days), subjects received an oral weekly maintenance dose of 250 mg over 6 months. Blood was collected after the last split loading dose then at weeks 4, 8 and 16 for group A, and at weeks 13 and 26 for group B. Plasma mefloquine concentrations were measured by high-performance liquid chromatography (HPLC). Pharmacokinetic modelling was performed using NONMEM. Results A two-compartment model with inter-occasion variability (IOV) for clearance satisfactorily described the pharmacokinetics. Typical values were clearance (CL/F, 2.09 l/h), central volume of distribution (V1/F, 528 l), absorption rate constant (KA, 0.24 h⁻¹⁾, inter-compartmental clearance (Q/F, 12.5 l/h), peripheral volume of distribution (V2/F, 483 l) and elimination half-life (t _1/2, 14.0 days). Weight had a positive influence on central volume but was insufficient to warrant dosage adjustments. The inter-individual variability (coefficient of variation, CV%) for CL/F and V1/F was 24.4% and 29.6%, respectively. The IOV for CL/F was 17.8%. The proportional residual error (CV%) for groups A and B was 11.5% and 19.5%, respectively, and the additive error standard deviation (SD) was 57 ng/ml and 149 ng/ml, respectively. Conclusion The typical parameter values were comparable with those estimated in much smaller cohorts of healthy subjects and in malaria patients treated with single-dose mefloquine. The lower unexplained variability in the blinded study suggested these subjects may have been more compliant in taking their medication than soldiers in the open-label study.     

Population pharmacokinetics of carbamazepine in Singapore epileptic patients

AIMS: To document the population pharmacokinetics of carbamazepine in patients with epilepsy living in Singapore, the majority of whom are of Chinese origin and others of minority races. METHODS: Steady-state plasma carbamazepine concentration data were gathered during routine care from various hospitals in Singapore for patients with epilepsy. Age, body weight, gender, race, formulation and concurrent medication (for other illnesses) were the fixed effects (covariates) tested simultaneously for their influence on the population mean of carbamazepine clearance, using the nonlinear mixed-effects model, in the NONMEM program. RESULTS: No age, gender, race, or formulation-related effect was found. Body weight (W), age (A) and concurrent medication with phenobarbitone (PB) emerged as the determinants of carbamazepine clearance (CL). The final regression model for carbamazepine clearance found best to describe the data was CL = 40.7 x A(0.494) x W(-1.17) x 1.44PB where CL is in l day(-1) kg(-1), A is in years, W is in kg and PB = 0 for a patient on carbamazepine only and PB = 1 for a patient on concomitant PB. The corresponding interindividual variability (CV%) in CL, described by using an exponential model, was 21.4%, and the residual error, described by using an exponential error model, was 18.2%. Predictive performance of this population covariate model was evaluated by Bayesian forecasting in a similar, but independent cohort of patients. There was no statistically significant bias between predicted and measured plasma carbamazepine concentrations. The population mean value of carbamazepine clearance obtained was similar to that previously reported for patients with a very different ethnic (Caucasians and Blacks) or geographical background (South Africa, Europe and USA). CONCLUSIONS: The derived covariate regression model reasonably predicted concentrations in the separate validation Singapore patient data set. The correlation between carbamazepine clearance and patient-specific characteristics may thus allow dosage adjustment to be made to achieve target steady-state plasma concentrations.     

Population pharmacokinetics and pharmacodynamics of warfarin in healthy young adults

The population pharmacokinetics and pharmacological response — prothrombin complex activity and factor VII activity — were studied in a group of 48 normal, healthy young volunteers. Population parameter estimates were obtained using a standard two-stage method, a nonlinear mixed effect model (NONMEM) and a two-stage Bayesian method (EM algorithm). A modified sigmoid-Imax model was used to relate the concentration of s-warfarin to the rate of clotting factor synthesis. The three methods produced similar estimates of the population pharmacokinetic parameters, although the standard two-stage method overestimated the contribution of the pharmacokinetic parameters to the interindividual variability. It was not possible to partition the interindividual variability in response between the pharmacodynamic parameters with the NONMEM procedure: the estimates obtained from the EM algorithm were generally in good agreement with those obtained using the standard two-stage approach. The variability in the warfarin concentration contributed at most only 40% of the observed variability in the pharmacological response, and then only for times greater than 96 h after the dose. Most of the variability in the pharmacodynamics was due to interindividual differences in the clotting factor degradation rate constant and C_50,s, the s-warfarin concentration causing a 50% decrease in synthesis rate.     

A mechanistic model for the sex-specific response to nalbuphine and naloxone in postoperative pain

We develop a mechanistic model for post-operative pain and apply it to describe the pharmacodynamic effects of the kappa-opioids nalbuphine and naloxone administered either alone or in combination in patients after surgical removal of one or more madibular third molar teeth. Data were obtained from 6 clinical studies in which a total of 304 patients were intravenously administered single doses of 2.5, 5, 10 or 20 mg of nalbuphine. Some groups also received 0.2 or 0.4 mg of naloxone. A total of 3,040 Visual analog scale (VAS) pain ratings were recorded at 20 min intervals for 3 h after drug administration. We used a two-site indirect action model to describe early and late pain and to incorporate the effect of nalbuphine and naloxone on pain over time. A mixed effects statistical model was used to account for inter- and intra-individual variability. Our model estimated the population average baseline pain score in men to be lower than that in women (68 vs. 76 mm on the 100 mm VAS scale). The model confirmed a late increase in pain (anti-analgesia) and estimated the lag time for the start of anti-analgesia to be 73 min after study drug administration. The maximum early phase pain score is 81.6 mm while the maximum anti-analgesia is 16.1 mm. The nalbuphine dose required to reduce early pain by 50% (ED₅₀) was estimated to be 5.85 mg and the naloxone dose required to reduce late phase pain by 50% was estimated to be 0.5 mg. The model confirmed the results from conventional statistical analyses performed previously on individual studies.     

A trial of carbamazepine in borderline personality disorder

Borderline personality disorder does not have a first choice pharmacological treatment. We studied 20 borderline inpatients in a double-blind parallel placebo-controlled trial with carbamazepine for a mean of 30.9 days. No significant positive effects of the drug were found.