Amikacin initial dosage in patients with hypoalbuminaemia: an interactive tool based on a population pharmacokinetic approach

2020 ◽  
Vol 75 (8) ◽  
pp. 2222-2231
Author(s):  
Jonás Samuel Pérez-Blanco ◽  
Eva María Sáez Fernández ◽  
M Victoria Calvo ◽  
José M Lanao ◽  
Ana Martín-Suárez
Keyword(s):  
Initial Dose ◽  
Goodness Of Fit ◽  
Plasma Concentrations ◽  
Visual Predictive Check ◽  
Initial Dosage ◽  
Pharmacokinetic Parameters ◽  
Population Pharmacokinetic ◽  
Parameter Estimates ◽  
Interactive Model ◽  
Model Based

Abstract Objectives To characterize amikacin population pharmacokinetics in patients with hypoalbuminaemia and to develop a model-based interactive application for amikacin initial dosage. Methods A population pharmacokinetic model was developed using a non-linear mixed-effects modelling approach (NONMEM) with amikacin concentration–time data collected from clinical practice (75% hypoalbuminaemic patients). Goodness-of-fit plots, minimum objective function value, prediction-corrected visual predictive check, bootstrapping, precision and bias of parameter estimates were used for model evaluation. An interactive model-based simulation tool was developed in R (Shiny and R Markdown). Cmax/MIC ratio, time above MIC and AUC/MIC were used for optimizing amikacin initial dose recommendation. Probabilities of reaching targets were calculated for the dosage proposed. Results A one-compartment model with first-order linear elimination best described the 873 amikacin plasma concentrations available from 294 subjects (model development and external validation groups). Estimated amikacin population pharmacokinetic parameters were CL (L/h) = 0.525 + 4.78 × (CKD-EPI/98) × (0.77 × vancomycin) and V (L) = 26.3 × (albumin/2.9)−0.51 × [1 + 0.006 × (weight − 70)], where CKD-EPI is calculated with the Chronic Kidney Disease Epidemiology Collaboration equation. AMKdose is a useful interactive model-based application for a priori optimization of amikacin dosage, using individual patient and microbiological information together with predefined pharmacokinetic/pharmacodynamic (PKPD) targets. Conclusions Serum albumin, total bodyweight, estimated glomerular filtration rate (using the CKD-EPI equation) and co-medication with vancomycin showed a significant impact on amikacin pharmacokinetics. A powerful interactive initial dose-finding tool has been developed and is freely available online. AMKdose could be useful for guiding initial amikacin dose selection before any individual pharmacokinetic information is available.

Estimation of Phenytoin Pharmacokinetic Parameters in Saudi Epileptic Patients

Pharmacology ◽  
2019 ◽  
Vol 104 (1-2) ◽  
pp. 60-66 ◽  
Author(s):  
Saeed Alqahtani ◽  
Thuraya Alzaidi ◽  
Mashal Alotaibi ◽  
Abdullah Alsultan
Keyword(s):  
Body Weight ◽  
Plasma Concentrations ◽  
Elimination Rate ◽  
Total Daily Dose ◽  
Pharmacokinetic Parameters ◽  
Population Pharmacokinetic ◽  
Parameter Estimates ◽  
Linear Absorption ◽  
Significant Covariates ◽  
Saudi Patients

Objective: This study aimed to assess the population pharmacokinetics of phenytoin in Saudi patients and identify factors affecting therapeutic parameters. Method: A retrospective chart review was performed at King Saud University Medical City on patients treated with oral phenytoin. We used Monolix 4.4. for population pharmacokinetic modeling. A base model was developed to investigate several covariates, including age, gender, weight, total daily dose (TTD), and liver function test results. Results: The analysis included a total of 81 phenytoin plasma concentrations from 43 patients (70% male). Patients’ mean (± SD) age was 41 (±18.7) years and body weight was 65.4 (±17.7) kg. The patients received a phenytoin TDD of 330.5 (±104.5) mg/day, resulting in a trough concentration of 11.2 (±10.3) mg/L. The data were sufficiently described by the one-compartment open model with linear absorption and nonlinear elimination processes. Average parameter estimates for phenytoin volume of distribution (V), maximal elimination rate (Vmax), and Michaelis-Menten constant (Km) were 0.61 L/h/kg, 6.12 mg/kg/day, and 5.33 mg/L, respectively. The most significant covariates on phenytoin Vmax and Km were the age and body weight of the patients, along with valproic acid (VPA) cotherapy. Conclusion: The population pharmacokinetic model of phenytoin in Saudi patients found significant interindividual variability between subjects, which was affected by the patients’ age, body weight, and VPA cotherapy as the most significant covariates on phenytoin Vmax and Km. To provide guidance in drug dosage decisions, further studies are required to evaluate all factors that may potentially influence the pharmacokinetics of phenytoin.

scholarly journals Population Pharmacokinetics of Levofloxacin, Gatifloxacin, and Moxifloxacin in Adults with Pulmonary Tuberculosis

2007 ◽  
Vol 52 (3) ◽  
pp. 852-857 ◽  
Author(s):  
Charles A. Peloquin ◽  
David Jamil Hadad ◽  
Lucilia Pereira Dutra Molino ◽  
Moises Palaci ◽  
W. Henry Boom ◽  
...  
Keyword(s):  
Plasma Concentrations ◽  
University Hospital ◽  
Pharmacokinetic Parameters ◽  
Population Pharmacokinetic ◽  
Parameter Estimates ◽  
Maximum Plasma ◽  
Population Parameter ◽  
Time Data ◽  
Time Curve ◽  
Concentration Time

ABSTRACT The objective of this study was to determine the population pharmacokinetic parameters of levofloxacin, gatifloxacin, and moxifloxacin following multiple oral doses. Twenty-nine patients with tuberculosis at the University Hospital in Vitória, Brazil, participated. Subjects received multiple doses of one drug (levofloxacin, 1,000 mg daily, or gatifloxacin or moxifloxacin, 400 mg daily) as part of a 7-day study of early bactericidal activity. Serum samples were collected over 24 h after the fifth dose and assayed using validated high-performance liquid chromatography assays. Concentration-time data were analyzed using noncompartmental, compartmental, and population methods. The three drugs were well tolerated. Levofloxacin produced the highest maximum plasma concentrations (median, 15.55 μg/ml; gatifloxacin, 4.75 μg/ml; moxifloxacin, 6.13 μg/ml), largest volume of distribution (median, 81 liters; gatifloxacin, 79 liters; moxifloxacin, 63 liters), and longest elimination half-life (median, 7.4 h; gatifloxacin, 5.0 h; moxifloxacin, 6.5 h). A one-compartment model, with or without weight as a covariate, adequately described the data. Postmodeling simulations using median population parameter estimates closely approximated the median values from the original data. Area under the concentration-time curve/MIC ratios for free drug were high. All three quinolones showed favorable pharmacokinetic and pharmacodynamic indices, with the most favorable results in this population being seen with levofloxacin at the comparative doses used.

scholarly journals 1319. Pharmacokinetics of Ceftolozane/Tazobactam in Patients with Burns

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S670-S671
Author(s):  
Ronald G Hall ◽  
Jotam Pasipanodya ◽  
William C Putnam ◽  
John Griswold ◽  
Sharmila Dissanaike ◽  
...  
Keyword(s):  
Human Plasma ◽  
Kidney Injury ◽  
Compartment Model ◽  
Pharmacokinetic Parameters ◽  
Therapeutic Drug ◽  
Population Pharmacokinetic ◽  
Parameter Estimates ◽  
Population Parameter ◽  
Full Thickness ◽  
Severe Burns

Abstract Background Antimicrobial dosing in moderate/severe burns patients is complicated due to the potential unpredictable hyperdynamic pathophysiologic states including 1) hypoproteinemia, 2) acute kidney injury and 3) onset of septicemia. Therefore, distribution assumptions about the population pharmacokinetic (PopPK) profiles of either endogenous or xenobiotic pharmacophores in this patient population can lead to biased parameter estimates. In order to prevent potential bias an agnostic nonparametric adaptive grid approach to describe ceftolozane/tazobactam (C/T) PopPK profiles in patients with partial- and full-thickness burns was employed. Methods A human clinical PK study in burn patients was conducted using the standard approved dose of C/T (2 grams/1 gram). A single intravenous dose was administered over 60 minutes. Whole blood was obtained pre-dose and at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, 16, and 24 hours following the start of infusion. LC-MS/MS bioanalytical methods were developed, validated and employed to determine C/T concentrations in human plasma. PopPK were modeled using Pmetrics package for R. One-, two- and three-compartment models were examined and compared. The influence of several parameters, including %body surface area burns, creatinine clearance (CrCL), weight, albumin and age were tested. Results The bioanalytical method for determination of C/T in human plasma met all recommended criteria of the LC-MS/MS. Five males and one female (ages 24 to 66 years), contributed 148 plasma PK samples. The female had 35% partial-thickness burns. The males had full-thickness burns ranging from 27 to 66%. The median CrCL was 104 mL/min (range 73-148 mL/min). Two-compartment model with absorption (Ka) from compartment 1 to 2 and elimination from compartment 2 (Ke), with nonlinear interactions between C/T elimination and CrCL best described the data. Figure A show that bias was minimal. Importantly, both drugs exhibited marked variability for both volume and elimination (Table), since volume was bimodally distributed (Figure B). A) Observation-versus-Prediction; B) Estimated Ke, V and Ka population parameter densities Summary of pharmacokinetic parameters Conclusion C/T exhibited high variability surpassing that observed with severe infections, suggesting that dose adjustment and/or may be therapeutic drug monitoring may be needed to balance target attainment from dose-related toxicities. Disclosures Ronald G. Hall, II, PharmD, MSCS, Medical Titan Group (Grant/Research Support)Merck (Research Grant or Support)

scholarly journals External Evaluation of Population Pharmacokinetic Models and Bayes-Based Dosing of Infliximab

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1191
Author(s):  
Celine Konecki ◽  
Catherine Feliu ◽  
Yoann Cazaubon ◽  
Delphine Giusti ◽  
Marcelle Tonye-Libyh ◽  
...  
Keyword(s):  
Goodness Of Fit ◽  
Inflammatory Diseases ◽  
Plasma Concentrations ◽  
Population Pharmacokinetic ◽  
Pharmacokinetic Models ◽  
External Evaluation ◽  
Immunomodulatory Treatment ◽  
Weighted Residuals ◽  
Prediction Distribution ◽  
Target Plasma

Despite the well-demonstrated efficacy of infliximab in inflammatory diseases, treatment failure remains frequent. Dose adjustment using Bayesian methods has shown in silico its interest in achieving target plasma concentrations. However, most of the published models have not been fully validated in accordance with the recommendations. This study aimed to submit these models to an external evaluation and verify their predictive capabilities. Eight models were selected for external evaluation, carried out on an independent database (409 concentrations from 157 patients). Each model was evaluated based on the following parameters: goodness-of-fit (comparison of predictions to observations), residual error model (population weighted residuals (PWRES), individual weighted residuals (IWRES), and normalized prediction distribution errors (NPDE)), and predictive performances (prediction-corrected visual predictive checks (pcVPC) and Bayesian simulations). The performances observed during this external evaluation varied greatly from one model to another. The eight evaluated models showed a significant bias in population predictions (from −7.19 to 7.38 mg/L). Individual predictions showed acceptable bias and precision for six of the eight models (mean error of −0.74 to −0.29 mg/L and mean percent error of −16.6 to −0.4%). Analysis of NPDE and pcVPC confirmed these results and revealed a problem with the inclusion of several covariates (weight, concomitant immunomodulatory treatment, presence of anti-drug antibodies). This external evaluation showed satisfactory results for some models, notably models A and B, and highlighted several prospects for improving the pharmacokinetic models of infliximab for clinical-biological application.

scholarly journals Population Pharmacokinetics of Atazanavir in Patients with Human Immunodeficiency Virus Infection

2006 ◽  
Vol 50 (11) ◽  
pp. 3801-3808 ◽  
Author(s):  
Sara Colombo ◽  
Thierry Buclin ◽  
Matthias Cavassini ◽  
Laurent A. Décosterd ◽  
Amalio Telenti ◽  
...  
Keyword(s):  
Plasma Levels ◽  
Population Analysis ◽  
Pharmacokinetic Profile ◽  
Relative Bioavailability ◽  
Fixed Dose ◽  
Pharmacokinetic Parameters ◽  
Therapeutic Drug ◽  
Population Pharmacokinetic ◽  
Parameter Estimates ◽  
Genetic Traits

ABSTRACT Atazanavir (ATV) is a new azapeptide protease inhibitor recently approved and currently used at a fixed dose of either 300 mg once per day (q.d.) in combination with 100 mg ritonavir (RTV) or 400 mg q.d. without boosting. ATV is highly bound to plasma proteins and extensively metabolized by CYP3A4. Since ATV plasma levels are highly variable and seem to be correlated with both viral response and toxicity, dosage individualization based on plasma concentration monitoring might be indicated. This study aimed to assess the ATV pharmacokinetic profile in a target population of HIV patients, to characterize interpatient and intrapatient variability, and to identify covariates that might influence ATV disposition. A population analysis was performed with NONMEM with 574 plasma samples from a cohort of 214 randomly selected patients receiving ATV. A total of 346 randomly collected ATV plasma levels and 19 full concentration-time profiles at steady state were available. The pharmacokinetic parameter estimates were an oral clearance (CL) of 12.9 liters/h (coefficient of variation [CV], 26%), a volume of distribution of 88.3 liters (CV, 29%), an absorption rate constant of 0.405 h−1 (CV, 122%), and a lag time of 0.88 h. A relative bioavailability value was introduced to account for undercompliance due to infrequent follow-ups (0.81; CV, 45%). Among the covariates tested, only RTV significantly reduced CL by 46%, thereby increasing the ATV elimination half-life from 4.6 h to 8.8 h. The pharmacokinetic parameters of ATV were adequately described by a one-compartment population model. The concomitant use of RTV improved the pharmacokinetic profile. However, the remaining high interpatient variability suggests the possibility of an impact of unmeasured covariates, such as genetic traits or environmental influences. This population pharmacokinetic model, together with therapeutic drug monitoring and Bayesian dosage adaptation, can be helpful in the selection and adaptation of ATV doses.

scholarly journals Prediction of steady-state plasma concentrations of olanzapine in Chinese Han in patients based on a retrospective population pharmacokinetic model

2021 ◽  
Vol 20 (11) ◽  
pp. 2433-2441
Author(s):  
Xiaoyue Wang ◽  
Yong Han ◽  
Hong Zhou ◽  
Bin Cao ◽  
Miaomiao Zhu ◽  
...  
Keyword(s):  
Steady State ◽  
Smoking Status ◽  
Mental Health Center ◽  
Plasma Concentrations ◽  
Visual Predictive Check ◽  
Apparent Volume ◽  
Population Pharmacokinetic ◽  
Chinese Han ◽  
Mixed Effect ◽  
State Plasma

Purpose: To develop robust methods of establishing a population pharmacokinetics (Pop-PK) model of olanzapine, using existing hospital in-patient information, in order to predict the steady-state plasma concentration of olanzapine tablets in Chinese Han inpatients, thus providing guidance for individualized therapy for mental disorders.Methods: A retrospective study analyzing and predicting the steady-state plasma olanzapineconcentration was performed using nonlinear mixed-effect modeling (Phoenix® NLME8). The effects of ten potential covariates, including age, gender, Body Mass Index, fasting lipid, family history, alcohol and smoking status in 107 Chinese Han patients with steady-state plasma olanzapine concentration were collected from the hospital information system (HIS) in Wuhan Mental Health Center from Feb 2017 to Jul 2019.Results: The final model was validated using bootstrap and visual predictive check (VPC) and was found to fit the one-compartment mixed error model. Smoking status was found to be the only factor affecting olanzapine tablets clearance. The standard Pop-PK parameters apparent volume of distribution (VL/F) and clearance (CL/F) were 223 L and 12.4 Lꞏh-1, respectively.Conclusion: The Pop-PK model for olanzapine established with the data from HIS is effective inpredicting the plasma olanzapine tablets concentration of individual Chinese in-patients. This Pop-PK model approach can now be adapted to optimize other antipsychotic drugs.

scholarly journals Estimation of Pharmacokinetic Parameters of Continuous Intravenous Flucloxacillin infusion in the Outpatient Settings (PKFLUCLOX)

2018 ◽  
Author(s):  
Nilar Lwin ◽  
Zheng Liu ◽  
Mark Loewenthal ◽  
Pauline Dobson ◽  
Ji Woong Yoo ◽  
...  
Keyword(s):  
Steady State ◽  
Continuous Infusion ◽  
Time Course ◽  
Plasma Concentrations ◽  
Compartment Model ◽  
Pharmacokinetic Analysis ◽  
Pharmacokinetic Parameters ◽  
Population Pharmacokinetic ◽  
Device Removal ◽  
Standard Dosage

Flucloxacillin, a beta-lactam antibiotic of the penicillin class, is considered first line therapy for methicillin sensitive Staphylococcus aureus (MSSA) in Australia. At our tertiary referral hospital in the home (HITH) program, it has been prescribed in a standard dosage of 8 grams per day by continuous infusion for more than 20 years. The aim of this observational study was to characterize the pharmacokinetic profile of flucloxacillin in patients who receive continuous infusion in the HITH setting, and to undertake population pharmacokinetic analysis performed with NONMEM software by comparing various structural models. This study utilised flucloxacillin concentrations from 44 separate specimens obtained from 23 patients. Twenty-five of these were collected immediately after elastomeric device removal, representing steady-state concentrations, and the remaining 19 were each collected at least 45 minutes after device removal to determine clearance of the drug. Plasma concentrations ranged from 13 to 194 mg/L with median steady-state concentration of 51.5 mg/L and inter-quartile range of 24.6 mg/L. The time-course of flucloxacillin was best described by a 1-compartment model. The best three covariates, CrCL (ΔOFV= -11.7), eGFR (ΔOFV= -5.9) and serum albumin (ΔOFV= -5.8) were found to be equivalent in terms of decreasing the OFV. CrCL was superior in explaining inter individual variability. The best model for flucloxacillin clearance was a one compartment model with CrCL as the sole covariate. The estimated population parameters were 9.5 L for volume of distribution and 8.1 L/h for flucloxacillin clearance.

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

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.

scholarly journals Aspects of Theophylline Clearance in Children

1997 ◽  
Vol 25 (5) ◽  
pp. 497-501 ◽  
Author(s):  
B. J. Anderson ◽  
N. H. G. Holford ◽  
G. A. Woollard
Keyword(s):  
Plasma Concentrations ◽  
Volume Of Distribution ◽  
Pharmacokinetic Parameters ◽  
Parameter Estimates ◽  
Power Model ◽  
Theophylline Clearance ◽  
Concentration Data ◽  
Model Parameter ◽  
Age Related ◽  
Menten Constant

Michaelis-Menten pharmacokinetic parameters for theophylline were estimated in a three-month infant following an accidental overdose of intravenous aminophylline. Fitting of time-concentration data was performed using nonlinear regression with MKMODEL. A mixed order elimination model was superior to a first order model. Parameter estimates were standardized to a 70 kg human using an allometric power model. Parameter estimates (SE) were: maximum rate of metabolism (Vmax) 71(42) mg.h–1, Michaelis-Menten constant (Km) 32.3 (33.5) mg.l–1, volume of distribution (Vd) 46.9 (2.6) l. This Michaelis-Menten constant is lower than that reported for adults and consequently non-linear elimination will occur at lower plasma concentrations in infants than in adults. Theophylline clearance has traditionally been reported as directly proportional to body weight. This per kilogram model gives an erroneous impression that clearance is greatest in early childhood and then decreases with age until adult rates are reached in late adolescence. Age-related clearance values reported in the literature were reviewed using an allometric 3/4 power model. This size model demonstrates that clearance increases in infancy and reaches adult rates in the first one to two years of life.

Sign in / Sign up

Export Citation Format

Share Document