Population Pharmacokinetics of Valproic Acid in Epileptic Patients at Prasat Neurological Institute

Objective: To develop a population pharmacokinetic model of valproic acid (VPA) and to evaluate factors influencing VPA pharmacokinetic parameters in epileptic patients. Material and Methods: Population pharmacokinetics analysis was performed using 215 VPA concentrations of 136 epileptic outpatients...

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Main Authors: Weenarat Senawin, Thitima Wattanavijitkul, Somchai Towanabut
Format: Article
Language:English
Published: Prince of Songkla University 2014-08-01
Series:Journal of Health Science and Medical Research (JHSMR)
Subjects:
Online Access:https://www.jhsmr.org/index.php/jhsmr/article/view/217
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spelling doaj-b09eb7d97a864ac59e3d501129608d9d2020-11-25T00:32:38ZengPrince of Songkla UniversityJournal of Health Science and Medical Research (JHSMR)2586-99812630-05592014-08-01324195206231Population Pharmacokinetics of Valproic Acid in Epileptic Patients at Prasat Neurological InstituteWeenarat Senawin0Thitima Wattanavijitkul1Somchai Towanabut2Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Phathumwan, Bangkok 10330,Department of Pharmacy Practice, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Phathumwan, Bangkok 10330,Department of Neurology, Prasat Neurological Institute, Ratchathewi, Bangkok 10330,Objective: To develop a population pharmacokinetic model of valproic acid (VPA) and to evaluate factors influencing VPA pharmacokinetic parameters in epileptic patients. Material and Methods: Population pharmacokinetics analysis was performed using 215 VPA concentrations of 136 epileptic outpatients receiving oral VPA from routine clinical data at Prasat Neurological Institute. A non-linear mixed effects one compartment model with first order absorption and elimination was fit to the data using the nonlinear mixed effects model (NONMEM®) software package. A first-order conditional estimation method with interaction (FOCEI) was used for parameter estimation. Interindividual variability and residual variability were estimated using proportional model. Model validation was performed using 1,000 simulations based on the bootstrap method. Results: Base on the final model, the apparent oral clearance (CL/F) of VPA was 0.585 L/hr, apparent oral volume of distributon (Vd/F) was 23 L and absorption rate constant (Ka) was fixed to 0.35 hr-1. Significant covariates on CL/F were the daily dose of VPA, co-administered phenytoin and body weight. The final model for CL/F of VPA was CL/F = 0.585 x [1+0.000362(DOSE-1,000)] x [1+0.379PHT] x [1+0.00798(WT-61.9)]. The interindividual variability in CL/F was 16.46% and residual variability was 28.05%. The 95% CI of all parameters were similar to the range obtained from the bootstrap, indicating that the final model estimates were reliable. Conclusion: VPA pharmacokinetics from routine clinical data was best described by one compartment model with first order absorption and elimination. The daily dose of VPA, co-administered phenytoin and body weight were significant covariates influencing CL/F of VPA. These factors should be considered when defining VPA dosage regimens in epileptic patients.https://www.jhsmr.org/index.php/jhsmr/article/view/217nonlinear mixed effect modelingnonmem®epilepsynonlinear mixed-effect modelingnonmem®population pharmacokineticsvalproic acid
collection DOAJ
language English
format Article
sources DOAJ
author Weenarat Senawin
Thitima Wattanavijitkul
Somchai Towanabut
spellingShingle Weenarat Senawin
Thitima Wattanavijitkul
Somchai Towanabut
Population Pharmacokinetics of Valproic Acid in Epileptic Patients at Prasat Neurological Institute
Journal of Health Science and Medical Research (JHSMR)
nonlinear mixed effect modeling
nonmem®
epilepsy
nonlinear mixed-effect modeling
nonmem®
population pharmacokinetics
valproic acid
author_facet Weenarat Senawin
Thitima Wattanavijitkul
Somchai Towanabut
author_sort Weenarat Senawin
title Population Pharmacokinetics of Valproic Acid in Epileptic Patients at Prasat Neurological Institute
title_short Population Pharmacokinetics of Valproic Acid in Epileptic Patients at Prasat Neurological Institute
title_full Population Pharmacokinetics of Valproic Acid in Epileptic Patients at Prasat Neurological Institute
title_fullStr Population Pharmacokinetics of Valproic Acid in Epileptic Patients at Prasat Neurological Institute
title_full_unstemmed Population Pharmacokinetics of Valproic Acid in Epileptic Patients at Prasat Neurological Institute
title_sort population pharmacokinetics of valproic acid in epileptic patients at prasat neurological institute
publisher Prince of Songkla University
series Journal of Health Science and Medical Research (JHSMR)
issn 2586-9981
2630-0559
publishDate 2014-08-01
description Objective: To develop a population pharmacokinetic model of valproic acid (VPA) and to evaluate factors influencing VPA pharmacokinetic parameters in epileptic patients. Material and Methods: Population pharmacokinetics analysis was performed using 215 VPA concentrations of 136 epileptic outpatients receiving oral VPA from routine clinical data at Prasat Neurological Institute. A non-linear mixed effects one compartment model with first order absorption and elimination was fit to the data using the nonlinear mixed effects model (NONMEM®) software package. A first-order conditional estimation method with interaction (FOCEI) was used for parameter estimation. Interindividual variability and residual variability were estimated using proportional model. Model validation was performed using 1,000 simulations based on the bootstrap method. Results: Base on the final model, the apparent oral clearance (CL/F) of VPA was 0.585 L/hr, apparent oral volume of distributon (Vd/F) was 23 L and absorption rate constant (Ka) was fixed to 0.35 hr-1. Significant covariates on CL/F were the daily dose of VPA, co-administered phenytoin and body weight. The final model for CL/F of VPA was CL/F = 0.585 x [1+0.000362(DOSE-1,000)] x [1+0.379PHT] x [1+0.00798(WT-61.9)]. The interindividual variability in CL/F was 16.46% and residual variability was 28.05%. The 95% CI of all parameters were similar to the range obtained from the bootstrap, indicating that the final model estimates were reliable. Conclusion: VPA pharmacokinetics from routine clinical data was best described by one compartment model with first order absorption and elimination. The daily dose of VPA, co-administered phenytoin and body weight were significant covariates influencing CL/F of VPA. These factors should be considered when defining VPA dosage regimens in epileptic patients.
topic nonlinear mixed effect modeling
nonmem®
epilepsy
nonlinear mixed-effect modeling
nonmem®
population pharmacokinetics
valproic acid
url https://www.jhsmr.org/index.php/jhsmr/article/view/217
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