Population Pharmacokinetic Study of Prophylactic Fluconazole in Preterm Infants for Prevention of Invasive Candidiasis

ABSTRACT Fluconazole is an antifungal agent with reported evidence for its prophylactic effect against systemic fungal infection in preterm infants. The aim of this study was to build a population pharmacokinetic model to evaluate the pharmacokinetic characteristics of intravenous and oral fluconazole in preterm infants with the current prophylactic fluconazole dosing regimen. A pharmacokinetic model was developed using 301 fluconazole concentrations from 75 preterm infants with a baseline body weight (WT) ranging from 0.5 to 1.5 kg and an estimated glomerular filtration rate (eGFR) ranging from 12.9 to 58.5 ml/min/1.73 m2. Eligible infants received an intravenous or oral dose of 3 mg/kg of body weight of fluconazole, twice weekly with a ≥72-h dose interval, for 4 weeks. The model was qualified with basic goodness-of-fit diagnostics, visual predictive checks, and bootstrapping. The fluconazole pharmacokinetics was well described with a one-compartment linear model with a proportional residual error. The population clearance (CL) and volume of distribution (V) were derived as 0.0197 × (WT/1.00)0.746 × (eGFR/25.0)0.463 × exp(η) and 1.04 × WT × exp(η), respectively. Such covariate analyses augment the awareness of the need for personalized dosing in preterm infants. (This study has been registered at ClinicalTrials.gov under identifier NCT01683760.)

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Dose Tailoring of Vancomycin Through Population Pharmacokinetic Modeling Among Surgical Patients in Pakistan

Frontiers in Pharmacology ◽

10.3389/fphar.2021.721819 ◽

2021 ◽

Vol 12 ◽

Author(s):

Muhammad Muaaz Munir ◽

Huma Rasheed ◽

Muhammad Imran Khokhar ◽

Rizwan Rasul Khan ◽

Hafiz Asad Saeed ◽

...

Keyword(s):

Body Weight ◽

Plasma Concentration ◽

Goodness Of Fit ◽

Volume Of Distribution ◽

Surgical Patients ◽

Pharmacokinetic Parameters ◽

Population Pharmacokinetic ◽

Time Data ◽

Concentration Data ◽

Population Pharmacokinetic Modeling

Background: Vancomycin is a narrow therapeutic agent, and it is necessary to optimize the dose to achieve safe therapeutic outcomes. The purpose of this study was to identify the significant covariates for vancomycin clearance and to optimize the dose among surgical patients in Pakistan.Methods: Plasma concentration data of 176 samples collected from 58 surgical patients treated with vancomycin were used in this study. A population pharmacokinetic model was developed on NONMEM® using plasma concentration–time data. The effect of all available covariates was evaluated on the pharmacokinetic parameters of vancomycin by stepwise covariate modeling. The final model was evaluated using bootstrap, goodness-of-fit plots, and visual predictive checks.Results: The pharmacokinetics of vancomycin followed a one-compartment model with first-order elimination. The vancomycin clearance (CL) and volume of distribution (Vd) were 2.45 L/h and 22.6 l, respectively. Vancomycin CL was influenced by creatinine clearance (CRCL) and body weight of the patients; however, no covariate was significant for its effect on the volume of distribution. Dose tailoring was performed by simulating dosage regimens at a steady state based on the CRCL of the patients. The tailored doses were 400, 600, 800, and 1,000 mg for patients with a CRCL of 20, 60, 100, and 140 ml/min, respectively.Conclusion: Vancomycin CL is influenced by CRCL and body weight of the patient. This model can be helpful for the dose tailoring of vancomycin based on renal status in Pakistani patients.

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Influence of Mechanical Ventilation on the Pharmacokinetics of Vancomycin Administered by Continuous Infusion in Critically Ill Patients

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01249-17 ◽

2017 ◽

Vol 61 (12) ◽

Cited By ~ 9

Author(s):

Susanna Edith Medellín-Garibay ◽

Silvia Romano-Moreno ◽

Pilar Tejedor-Prado ◽

Noelia Rubio-Álvaro ◽

Aida Rueda-Naharro ◽

...

Keyword(s):

Mechanical Ventilation ◽

Creatinine Clearance ◽

Continuous Infusion ◽

Critically Ill ◽

Critically Ill Patients ◽

Population Pharmacokinetic Model ◽

Pharmacokinetic Model ◽

Volume Of Distribution ◽

Stochastic Simulations ◽

Population Pharmacokinetic

ABSTRACT Pathophysiological changes involved in drug disposition in critically ill patients should be considered in order to optimize the dosing of vancomycin administered by continuous infusion, and certain strategies must be applied to reach therapeutic targets on the first day of treatment. The aim of this study was to develop a population pharmacokinetic model of vancomycin to determine clinical covariates, including mechanical ventilation, that influence the wide variability of this antimicrobial. Plasma vancomycin concentrations from 54 critically ill patients were analyzed simultaneously by a population pharmacokinetic approach. A nomogram for dosing recommendations was developed and was internally evaluated through stochastic simulations. The plasma vancomycin concentration-versus-time data were best described by a one-compartment open model with exponential interindividual variability associated with vancomycin clearance and the volume of distribution. Residual error followed a homoscedastic trend. Creatinine clearance and body weight significantly dropped the objective function value, showing their influence on vancomycin clearance and the volume of distribution, respectively. Characterization based on the presence of mechanical ventilation demonstrated a 20% decrease in vancomycin clearance. External validation (n = 18) was performed to evaluate the predictive ability of the model; median bias and precision values were 0.7 mg/liter (95% confidence interval [CI], −0.4, 1.7) and 5.9 mg/liter (95% CI, 5.4, 6.4), respectively. A population pharmacokinetic model was developed for the administration of vancomycin by continuous infusion to critically ill patients, demonstrating the influence of creatinine clearance and mechanical ventilation on vancomycin clearance, as well as the implications for targeting dosing rates to reach the therapeutic range (20 to 30 mg/liter).

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Clinical Pharmacokinetics of Irinotecan and Its Metabolites: A Population Analysis

Journal of Clinical Oncology ◽

10.1200/jco.2002.11.073 ◽

2002 ◽

Vol 20 (15) ◽

pp. 3293-3301 ◽

Cited By ~ 54

Author(s):

Rujia Xie ◽

Ron H.J. Mathijssen ◽

Alex Sparreboom ◽

Jaap Verweij ◽

Mats O. Karlsson

Keyword(s):

Tissue Distribution ◽

Goodness Of Fit ◽

Population Analysis ◽

Dose Range ◽

Central Compartment ◽

Volume Of Distribution ◽

Population Pharmacokinetic ◽

Clinical Pharmacokinetics ◽

Lactone Form ◽

Time Courses

PURPOSE: To build population pharmacokinetic (PK) models for irinotecan (CPT-11) and its currently identified metabolites. PATIENTS AND METHODS: Seventy cancer patients (24 women and 46 men) received 90-minute intravenous infusions of CPT-11 in the dose range of 175 to 300 mg/m2. The PK models were developed to describe plasma concentration profiles of the lactone and carboxylate forms of CPT-11 and 7-ethyl-10-hydroxycamptothecin (SN-38) and the total forms of SN-38 glucuronide (SN-38G), 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]-carbonyloxycamptothecin (APC), and 7-ethyl-10-[4-amino-1-piperidino]-carbonyloxycamptothecin (NPC) by using NONMEM. RESULTS: The interconversion between the lactone and carboxylate forms of CPT-11 was relatively rapid, with an equilibration half-life of 14 minutes in the central compartment and hydrolysis occurring at a rate five times faster than lactonization. The same interconversion also occurred in peripheral compartments. CPT-11 lactone had extensive tissue distribution (steady-state volume of distribution [Vss], 445 L) compared with the carboxylate form (Vss, 78 L, excluding peripherally formed CPT-11 carboxylate). Clearance (CL) was higher for the lactone form (74.3 L/h) compared with the carboxylate form (12.3 L/h). During metabolite data modeling, goodness of fit indicated a preference of SN-38 and NPC to be formed out of the lactone form of CPT-11, whereas APC could be modeled best by presuming formation from CPT-11 carboxylate. The interconversion between SN-38 lactone and carboxylate was slower than that of CPT-11, with the lactone form dominating at equilibrium. The CLs for SN-38 lactone and carboxylate were similar, but the lactone form had more extensive tissue distribution. CONCLUSION: Plasma data of CPT-11 and metabolites could be adequately described by this compartmental model, which may be useful in predicting the time courses, including interindividual variability, of all characterized substances after intravenous administrations of CPT-11.

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Population Pharmacokinetics and Dosing Optimization of Linezolid in Pediatric Patients

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02387-18 ◽

2019 ◽

Vol 63 (4) ◽

Cited By ~ 2

Author(s):

Si-Chan Li ◽

Qi Ye ◽

Hua Xu ◽

Long Zhang ◽

Yang Wang

Keyword(s):

Body Weight ◽

Population Pharmacokinetics ◽

Population Pharmacokinetic Model ◽

Pharmacokinetic Model ◽

Pediatric Patients ◽

Population Pharmacokinetic ◽

Pharmacokinetic Data ◽

Nonparametric Bootstrap ◽

Bootstrap Analysis ◽

Final Model

ABSTRACT Linezolid is a synthetic antibiotic very effective in the treatment of infections caused by Gram-positive pathogens. Although the clinical application of linezolid in children has increased progressively, data on linezolid pharmacokinetics in pediatric patients are very limited. The aim of this study was to develop a population pharmacokinetic model for linezolid in children and optimize the dosing strategy in order to improve therapeutic efficacy. We performed a prospective pharmacokinetic study of pediatric patients aged 0 to 12 years. The population pharmacokinetic model was developed using the NONMEM program. Goodness-of-fit plots, nonparametric bootstrap analysis, normalized prediction distribution errors, and a visual predictive check were employed to evaluate the final model. The dosing regimen was optimized based on the final model. The pharmacokinetic data from 112 pediatric patients ages 0.03 to 11.9 years were analyzed. The pharmacokinetics could best be described by a one-compartment model with first-order elimination along with body weight and the estimated glomerular filtration rate as significant covariates. Simulations demonstrated that the currently approved dosage of 10 mg/kg of body weight every 8 h (q8h) would lead to a high risk of underdosing for children in the presence of bacteria with MICs of ≥2 mg/liter. To reach the pharmacokinetic target, an elevated dosage of 15 or 20 mg/kg q8h may be required for them. The population pharmacokinetics of linezolid were characterized in pediatric patients, and simulations provide an evidence-based approach for linezolid dosage individualization.

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Modeling Population Pharmacokinetics of Lidocaine

Anesthesiology ◽

10.1097/00000542-200104000-00007 ◽

2001 ◽

Vol 94 (4) ◽

pp. 566-573 ◽

Cited By ~ 13

Author(s):

Jette A. Kuipers ◽

Fred Boer ◽

Annemiek de Roode ◽

Erik Olofsen ◽

James G. Bovill ◽

...

Keyword(s):

Cardiac Output ◽

Pharmacokinetic Model ◽

Population Pharmacokinetic ◽

Ratio Test ◽

Pharmacokinetic Models ◽

Population Pharmacokinetic Modeling ◽

Population Pharmacokinetic Study ◽

Electrical Bioimpedance ◽

Demographic Covariates ◽

The Individual

Background Inclusion of cardiac output and other physiologic parameters, in addition to or instead of, demographic variables might improve the population pharmacokinetic modeling of lidocaine. Methods Thirty-one patients were included in a population pharmacokinetic study of lidocaine. After bolus injection of lidocaine (1 mg/kg), 22 or 10 blood samples per patient were taken from a radial artery. During the experiment, cardiac output was measured using a thoracic electrical bioimpedance method. The following four population pharmacokinetic models were constructed and their performances investigated: a model with no covariates, a model with cardiac output as covariate, a model with demographic covariates, and a model with both cardiac output and demographic characteristics as covariates. Model discrimination was performed with the likelihood ratio test. Results Inclusion of cardiac output resulted in a significant improvement of the pharmacokinetic model, but inclusion of demographic covariates was even better. However, the best model was obtained by inclusion of both demographic covariates and cardiac output in the pharmacokinetic model. Conclusions When population pharmacokinetic models are used for individualization of dosing schedules, physiologic covariates, e.g., cardiac output, can improve their ability to predict the individual kinetics.

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Pharmacokinetics of Ceftaroline in Normal Body Weight and Obese (Classes I, II, and III) Healthy Adult Subjects

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00498-15 ◽

2015 ◽

Vol 59 (7) ◽

pp. 3956-3965 ◽

Cited By ~ 14

Author(s):

Julie Ann Justo ◽

Stockton M. Mayer ◽

Manjunath P. Pai ◽

Melinda M. Soriano ◽

Larry H. Danziger ◽

...

Keyword(s):

Body Weight ◽

Healthy Adult ◽

Plasma Concentrations ◽

Area Under The Curve ◽

Total Body Weight ◽

Pharmacokinetic Profile ◽

Volume Of Distribution ◽

Population Pharmacokinetic ◽

Ceftaroline Fosamil ◽

Plasma And Urine Samples

ABSTRACTThe pharmacokinetic profile of ceftaroline has not been well characterized in obese adults. The purpose of this study was to evaluate the pharmacokinetics of ceftaroline in 32 healthy adult volunteers aged 18 to 50 years in the normal, overweight, and obese body size ranges. Subjects were evenly assigned to 1 of 4 groups based on their body mass index (BMI) and total body weight (TBW) (ranges, 22.1 to 63.5 kg/m2and 50.1 to 179.5 kg, respectively). Subjects in the lower-TBW groups were matched by age, sex, race/ethnicity, and serum creatinine to the upper-BMI groups. Serial plasma and urine samples were collected over 12 h after the start of the infusion, and the concentrations of ceftaroline fosamil (prodrug), ceftaroline, and ceftaroline M-1 (inactive metabolite) were assayed. Noncompartmental and population pharmacokinetic analyses were used to evaluate the data. The mean plasma ceftaroline maximum concentration and area under the curve were ca. 30% lower in subjects with a BMI of ≥40 kg/m2compared to those <30 kg/m2. A five-compartment pharmacokinetic model with zero-order infusion and first-order elimination optimally described the plasma concentration-time profiles of the prodrug and ceftaroline. Estimated creatinine clearance (eCLCR) and TBW best explained ceftaroline clearance and volume of distribution, respectively. Although lower ceftaroline plasma concentrations were observed in obese subjects, Monte Carlo simulations suggest the probability of target attainment is ≥90% when the MIC is ≤1 μg/ml irrespective of TBW or eCLCR. No dosage adjustment for ceftaroline appears to be necessary based on TBW alone in adults with comparable eCLCR. Confirmation of these findings in infected obese patients is necessary to validate these findings in healthy volunteers. (This study has been registered at ClinicalTrials.gov under registration no. NCT01648127.)

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Population Pharmacokinetic Analysis of Cefaclor in Healthy Korean Subjects

Pharmaceutics ◽

10.3390/pharmaceutics13050754 ◽

2021 ◽

Vol 13 (5) ◽

pp. 754

Author(s):

Seung-Hyun Jeong ◽

Ji-Hun Jang ◽

Hea-Young Cho ◽

Yong-Bok Lee

Keyword(s):

Population Pharmacokinetic Model ◽

Pharmacokinetic Model ◽

Population Pharmacokinetic Analysis ◽

Pharmacokinetic Analysis ◽

Pharmacokinetic Parameters ◽

Population Pharmacokinetic ◽

Factors Affecting ◽

Population Pharmacokinetic Study ◽

Final Population ◽

Subject Variability

The aims of this study were: (1) to perform population pharmacokinetic analysis of cefaclor in healthy Korean subjects, and (2) to investigate possible effects of various covariates on pharmacokinetic parameters of cefaclor. Although cefaclor belongs to the cephalosporin family antibiotic that has been used in various indications, there have been very few population studies on factors affecting its pharmacokinetics. Therefore, this study is very important in that effective therapy could be possible through a population pharmacokinetic study that explores effective covariates related to cefaclor pharmacokinetic diversity between individuals. Pharmacokinetic results of 48 subjects with physical and biochemical parameters were used for the population pharmacokinetic analysis of cefaclor. A one-compartment with lag-time and first-order absorption/elimination was constructed as a base model and extended to include covariates that could influence between-subject variability. Creatinine clearance and body weight significantly influenced systemic clearance and distribution volume of cefaclor. Cefaclor’s final population pharmacokinetic model was validated and some of the population’s pharmacokinetic diversity could be explained. Herein, we first describe the establishment of a population pharmacokinetic model of cefaclor for healthy Koreans that might be useful for customizing cefaclor or exploring additional covariates in patients.

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Population Pharmacokinetics of Pyrazinamide in Patients with Tuberculosis

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02625-16 ◽

2017 ◽

Vol 61 (6) ◽

Cited By ~ 12

Author(s):

Abdullah Alsultan ◽

Rada Savic ◽

Kelly E. Dooley ◽

Marc Weiner ◽

William Whitworth ◽

...

Keyword(s):

Body Weight ◽

Therapeutic Target ◽

Volume Of Distribution ◽

Current Treatment ◽

Population Pharmacokinetic ◽

Maximum Plasma ◽

Target Attainment ◽

Time Curve ◽

The Mean ◽

Higher Doses

ABSTRACT The current treatment used for tuberculosis (TB) is lengthy and needs to be shortened and improved. Pyrazinamide (PZA) has potent sterilizing activity and has the potential to shorten the TB treatment duration, if treatment is optimized. The goals of this study were (i) to develop a population pharmacokinetic (PK) model for PZA among patients enrolled in PK substudies of Tuberculosis Trial Consortium (TBTC) trials 27 and 28 and (ii) to determine covariates that affect PZA PK. (iii) We also performed simulations and target attainment analysis using the proposed targets of a maximum plasma concentration (C max) of >35 μg/ml or an area under the concentration-versus-time curve (AUC) of >363 μg · h/ml to see if higher weight-based dosing could improve PZA efficacy. Seventy-two patients participated in the substudies. The mean (standard deviation [SD]) C max was 30.8 (7.4) μg/ml, and the mean (SD) AUC from time zero to 24 h (AUC0–24) was 307 (83) μg · h/ml. A one-compartment open model best described PZA PK. Only body weight was a significant covariate for PZA clearance. Women had a lower volume of distribution (V/F) than men, and both clearance (CL/F) and V/F increased with body weight. Our simulations show that higher doses of PZA (>50 mg/kg of body weight) are needed to achieve the therapeutic target of an AUC/MIC of >11.3 in >80% of patients, while doses of >80 mg/kg are needed for target attainment in 90% of patients, given specific assumptions about MIC determinations. For the therapeutic targets of a C max of >35 μg/ml and/or an AUC of >363 μg · h/ml, doses in the range of 30 to 40 mg/kg are needed to achieve the therapeutic target in >90% of the patients. Further clinical trials are needed to evaluate the safety and efficacy of higher doses of PZA.

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Bayesian Parameter Estimates of Nelfinavir and Its Active Metabolite, Hydroxy-tert-Butylamide, in Infants Perinatally Infected with Human Immunodeficiency Virus Type 1

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.2.525-535.2005 ◽

2005 ◽

Vol 49 (2) ◽

pp. 525-535 ◽

Cited By ~ 4

Author(s):

Salomé Payen ◽

Albert Faye ◽

Alexandra Compagnucci ◽

Carlo Giaquinto ◽

Diana Gibbs ◽

...

Keyword(s):

Human Immunodeficiency Virus ◽

Body Weight ◽

Human Immunodeficiency Virus Type ◽

Active Metabolite ◽

Population Pharmacokinetic Model ◽

Pharmacokinetic Model ◽

Population Pharmacokinetic ◽

Parameter Estimates ◽

Immunodeficiency Virus

ABSTRACT The objective of the present study was to develop a population pharmacokinetic model for nelfinavir mesylate (NFV) and nelfinavir hydroxy-tert-butylamide (M8), the most abundant metabolite of NFV, in infants vertically infected with human immunodeficiency virus type 1 and participating in the Paediatric European Network for Treatment of AIDS 7 study. Plasma NFV concentrations were determined during repeated NFV administrations (two to three times a day). Eighteen infants younger that age 2 years participated in this study. The doses administered ranged from 71 to 203 mg/kg of body weight/day. Pharmacokinetic parameter estimates were obtained by a compartmental approach by using a kinetic model to simultaneously fit NFV and M8 (active metabolite) concentrations. M8 was shown to be formation rate limited and was characterized by first-order rate constants of formation and elimination. Body weight was found to be a more appropriate predictor than age of the changes in (i) the rate of metabolism, (ii) the elimination rate constant of NFV, and (iii) NFV clearance. Population parameters were computed to account for the relationship between the rate of metabolism and body weight. The estimated NFV and M8 elimination half-lives were 4.3 and 2.04 h, respectively. The estimated NFV clearance was 2.13 liters/h/kg. The M8 concentration-to-NFV concentration ratio was 0.64 ± 0.44. In conclusion, the population pharmacokinetic model describing the dispositions of NFV and M8 should facilitate the design of future studies to elucidate the relative contributions of the parent compound and M8 to the pharmacological and toxic effects of NFV therapy.

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ORGAN FAILURE AND C-REACTIVE PROTEIN BOTH AFFECT MIDAZOLAM CLEARANCE IN CRITICALLY ILL CHILDREN: A POPULATION PK MODEL

Archives of Disease in Childhood ◽

10.1136/archdischild-2015-310148.16 ◽

2015 ◽

Vol 101 (1) ◽

pp. e1.8-e1

Author(s):

Nienke J Vet ◽

Janneke M Brussee ◽

Matthijs de Hoog ◽

Miriam G Mooij ◽

Carin WM Verlaat ◽

...

Keyword(s):

Body Weight ◽

Organ Failure ◽

Critically Ill ◽

Volume Of Distribution ◽

Critically Ill Children ◽

Population Pharmacokinetic ◽

C Reactive Protein ◽

Population Pharmacokinetic Modeling ◽

Reactive Protein ◽

Organ Failures

ObjectivesTo study the effect of organ failure and inflammation on midazolam clearance in critically ill children, using population pharmacokinetic modeling.MethodsA total of 83 critically ill children (median age 5 months (range 1 day-17 years), n=523 samples) receiving intravenous midazolam for continuous sedation during mechanical ventilation were included. Disease severity was described using the validated and clinically used scores PELOD, PIM2 and PRISM II. Cytokines (IL-1, IL-2, IL-6, TNF-a) and C-reactive protein (CRP) were used as markers for inflammation. A population pharmacokinetic model for midazolam was developed using NONMEM 7.3. Body weight, age, severity of organ failure and inflammatory markers were considered as potential covariates.ResultsIn a two-compartmental PK model, body weight was found as most significant covariate for clearance and volume of distribution. Moreover, both severity of organ failure (PELOD) and inflammation (IL6 and CRP) were significant determinants of clearance (p<0.01), and either of these factors improved the model significantly. With increasing number of organ failures, midazolam clearance significantly reduced. CRP was linearly correlated with clearance (slope −0.095), with higher CRP levels resulting in lower clearances. Either one of the covariates could explain part of the variability in clearance.ConclusionFor midazolam clearance, apart from body weight, we found organ failure reflected by the PELOD score, and inflammation reflected by IL6 and CRP, as significant covariates. Most likely this effect is due to reduced activity of CYP3A in critically ill mechanically ventilated children. Both CRP concentration and organ failure should be considered when dosing midazolam and potentially other CYP3A substrates in critically ill children.

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