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Farhan N, Dahal UP, Wahlstrom J. Development and Evaluation of Ontogeny Functions of the Major UDP-Glucuronosyltransferase Enzymes to Underwrite Physiologically Based Pharmacokinetic Modeling in Pediatric Populations. J Clin Pharmacol 2024. [PMID: 38898531 DOI: 10.1002/jcph.2484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 05/16/2024] [Indexed: 06/21/2024]
Abstract
Uridine 5'-diphospho-glucuronosyltransferases (UGTs) demonstrate variable expression in the pediatric population. Thus, understanding of age-dependent maturation of UGTs is critical for accurate pediatric pharmacokinetics (PK) prediction of drugs that are susceptible for glucuronidation. Ontogeny functions of major UGTs have been previously developed and reported. However, those ontogeny functions are based on in vitro data (i.e., enzyme abundance, in vitro substrate activity, and so on) and therefore, may not translate to in vivo maturation of UGTs in the clinical setting. This report describes meta-analysis of the literature to develop and compare ontogeny functions for 8 primary UGTs (UGT1A1, UGT1A4, UGT1A6, UGT1A9, UGT2B7, UGT2B10, UGT2B15, and UGT2B17) based on published in vitro and in vivo studies. Once integrated with physiologically based pharmacokinetics modeling models, in vivo activity-based ontogeny functions demonstrated somewhat greater prediction accuracy (mean squared error, MSE: 0.05) compared to in vitro activity (MSE: 0.104) and in vitro abundance-based ontogeny functions (MSE: 0.129).
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Affiliation(s)
- Nashid Farhan
- Pharmacokinetics and Drug Metabolism, Amgen Inc., South San Francisco, California, USA
| | - Upendra P Dahal
- Pharmacokinetics and Drug Metabolism, Amgen Inc., South San Francisco, California, USA
| | - Jan Wahlstrom
- Pharmacokinetics and Drug Metabolism, Amgen Inc., Thousand Oaks, California, USA
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Caleffi‐Marchesini ER, Herling AA, Macente J, Bonan RH, de Freitas Lima P, Moreno R, Alexandre V, Charbe NB, Borghi‐Pangoni FB, Cristofoletti R, Diniz A. Adult and pediatric physiologically-based biopharmaceutics modeling to explain lamotrigine immediate release absorption process. CPT Pharmacometrics Syst Pharmacol 2024; 13:208-221. [PMID: 37916262 PMCID: PMC10864931 DOI: 10.1002/psp4.13071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 09/17/2023] [Accepted: 09/25/2023] [Indexed: 11/03/2023] Open
Abstract
Physiologically-based biopharmaceutics modeling (PBBM) has potential to accelerate the development of new drug and formulations. An important application of PBBM is for special populations such as pediatrics that have pharmacokinetics dependent on the maturation process. Lamotrigine (LTG) is a Biopharmaceutics Classification System (BCS) II drug and is widely prescribed. Therefore, the goal of this study was to assess the biopharmaceutics risk of the low-soluble drug LTG when the ontogeny on gastrointestinal tract (GIT) physiological parameters are considered. An oral physiologically-based pharmacokinetic model and a PBBM were developed and verified using GastroPlus™ software for both adults and children (2-12 years old, 12-52 kg). The biopharmaceutics properties and GIT physiological parameters were evaluated by sensitivity analysis. High doses were simulated assuming a worst case scenario, that is, the dose of 200 mg for adults and 5 mg/kg (up to the maximum of 200 mg) for 2-year-old children. Although several authors have suggested that ontogeny may have an effect on gastrointestinal fluid volume, our study found no evidence of interference between fluid and dose volumes with in vivo dissolution of LTG. The most impactful parameter was found to be the gastric transit time. Therefore, the hypothesis is developed to examine whether LTG exhibits characteristics of a BCS II classification in vitro while showing BCS I-like behavior in vivo. This hypothesis could act as a base for conducting novel studies on model-informed precision dosing, tailored to specific populations and clinical conditions. In addition, it could be instrumental in assessing the influence of various release profiles on in vivo performance for both adult and pediatric populations.
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Affiliation(s)
| | - Amanda Antunes Herling
- Pharmacokinetics and Biopharmaceutics LaboratoryState University of MaringáMaringáPRBrazil
| | - Julia Macente
- Pharmacokinetics and Biopharmaceutics LaboratoryState University of MaringáMaringáPRBrazil
| | | | | | - Rafaela Moreno
- Centro Universitário Barão de MauáRibeirão PretoSPBrazil
| | - Veriano Alexandre
- Hospital das Clínicas, Faculdade de MedicinaUniversidade de São PauloRibeirão PretoSPBrazil
| | - Nitin Bharat Charbe
- Center for Pharmacometrics & Systems PharmacologyUniversity of FloridaOrlandoFloridaUSA
| | | | - Rodrigo Cristofoletti
- Center for Pharmacometrics & Systems PharmacologyUniversity of FloridaOrlandoFloridaUSA
| | - Andréa Diniz
- Pharmacokinetics and Biopharmaceutics LaboratoryState University of MaringáMaringáPRBrazil
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Abstract
Almost 50% of prescription drugs lack age-appropriate dosing guidelines and therefore are used "off-label." Only ~10% drugs prescribed to neonates and infants have been studied for safety or efficacy. Immaturity of drug metabolism in children is often associated with drug toxicity. This chapter summarizes data on the ontogeny of major human metabolizing enzymes involved in oxidation, reduction, hydrolysis, and conjugation of drugs. The ontogeny data of individual drug-metabolizing enzymes are important for accurate prediction of drug pharmacokinetics and toxicity in children. This information is critical for designing clinical studies to appropriately test pharmacological hypotheses and develop safer pediatric drugs, and to replace the long-standing practice of body weight- or surface area-normalized drug dosing. The application of ontogeny data in physiologically based pharmacokinetic model and regulatory submission are discussed.
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Dodin YI, Suyagh MF, Saleh MI, Nuseir ZT, Aburuz SM, Al-Qudah AA, Masri AT, Younes AM, Al-Ghazawi MA. Population Pharmacokinetics Modeling of Lamotrigine in Jordanian Epileptic Patients Using Dried Blood Spot Sampling. Drug Res (Stuttg) 2021; 71:429-437. [PMID: 34255318 DOI: 10.1055/a-1524-0913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AIMS To characterize the population pharmacokinetics of lamotrigine in Jordanian epileptic patients and to identify factors affecting therapeutic parameters. PATIENTS AND METHODS A population pharmacokinetics model for lamotrigine was established based on a prospectively collected data of 52 steady-state concentrations from 38 adult and pediatric patients with epilepsy. Lamotrigine concentrations were determined by a dried blood spot liquid chromatography method. Data were analyzed according to a one-compartment model with first-order absorption and elimination using the nonlinear mixed effect modeling program. The covariates effect of total body weight, gender, age, and co-medication with topiramate, carbamazepine, phenytoin, phenobarbital, and valproic acid on lamotrigine clearance were investigated using a stepwise forward addition followed by a stepwise backward elimination. RESULTS The final population pharmacokinetics model for lamotrigine clearance was as follows: CL/Fpop=θ1*exp (θ3*age)*exp (θ5*carbamazepine)*exp (θ6*valproic acid) , where θ1 is the relative clearance (L/hr) estimated, and θ3, θ5, and θ6 are the fixed parameters relating to age and co-medication with carbamazepine and valproic acid, respectively.The population mean value of lamotrigine total clearance generated in the final model (with covariates) was 2.12 L/hr. Inter-individual variability and residual unexplained variability expressed as the coefficient of variation was 37.1 and 26.1%, respectively. CONCLUSION Lamotrigine total clearance in the Jordanian patients is comparable to that reported by others for Caucasian patients. Age and concomitant therapy with carbamazepine and valproic acid significantly affected lamotrigine clearance, and accounted for 48% of its inter-individual variability.
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Affiliation(s)
- Yasmeen I Dodin
- Department of Biopharmaceutics and Clinical Pharmacy, Faculty of Pharmacy, The University of Jordan, Amman, Jordan
| | - Maysa F Suyagh
- Department of Biopharmaceutics and Clinical Pharmacy, Faculty of Pharmacy, The University of Jordan, Amman, Jordan
| | - Mohammad I Saleh
- Department of Biopharmaceutics and Clinical Pharmacy, Faculty of Pharmacy, The University of Jordan, Amman, Jordan
| | - Ziad T Nuseir
- Division of Neurology, Department of Internal Medicine, Faculty of Medicine, The University of Jordan, Amman, Jordan
| | - Salah M Aburuz
- Department of Biopharmaceutics and Clinical Pharmacy, Faculty of Pharmacy, The University of Jordan, Amman, Jordan
| | - Abdelkarim A Al-Qudah
- Division of Child Neurology, Department of Pediatrics, Faculty of Medicine, The University of Jordan, Amman, Jordan
| | - Amira T Masri
- Division of Child Neurology, Department of Pediatrics, Faculty of Medicine, The University of Jordan, Amman, Jordan
| | | | - Mutasim A Al-Ghazawi
- Department of Biopharmaceutics and Clinical Pharmacy, Faculty of Pharmacy, The University of Jordan, Amman, Jordan
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Yeung CHT, Ito S, Autmizguine J, Edginton AN. Incorporating Breastfeeding-Related Variability with Physiologically Based Pharmacokinetic Modeling to Predict Infant Exposure to Maternal Medication Through Breast Milk: a Workflow Applied to Lamotrigine. AAPS JOURNAL 2021; 23:70. [PMID: 34002327 DOI: 10.1208/s12248-021-00599-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 04/16/2021] [Indexed: 11/30/2022]
Abstract
Current methods to assess risk in infants exposed to maternal medication through breast milk do not specifically account for infants most vulnerable to high drug exposure. A workflow applied to lamotrigine incorporated variability in infant anatomy and physiology, milk intake volume, and milk concentration to predict infant exposure. An adult physiologically based pharmacokinetic model of lamotrigine was developed and evaluated. The model was scaled to account for growth and maturation of a virtual infant population (n=100). Daily infant doses were simulated using milk intake volume and concentration models described by a nonlinear equation of weight-normalized intake across infant age and a linear function on the relationship of observed milk concentrations and maternal doses, respectively. Average infant plasma concentration at steady state was obtained through simulation. Models were evaluated by comparing observed to simulated infant plasma concentrations from breastfeeding infants based on a 90% prediction interval (PI). Upper AUC ratio (UAR) was defined as a novel risk metric. Twenty-five paired (milk concentrations measured) and 18 unpaired (milk concentrations unknown) infant plasma samples were retrieved from the literature. Forty-four percent and 11% of the paired and unpaired infant plasma concentrations were outside of the 90% PI, respectively. Over all ages (0-7 months), unpaired predictions captured more observed infant plasma concentrations within 90% PI than paired. UAR was 0.18-0.44 when mothers received 200 mg lamotrigine, suggesting that infants can receive 18-44% of the exposure per dose as compared to adults. UARs determined for further medications could reveal trends to better classify at-risk mother-infant pairs.
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Affiliation(s)
- Cindy H T Yeung
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada
| | - Shinya Ito
- Division of Clinical Pharmacology and Toxicology, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Julie Autmizguine
- Department of Pediatrics & Department of Pharmacology and Physiology, Université de Montréal, Montréal, Québec, Canada.,Research Center, Centre Hospitalier Universitaire Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
| | - Andrea N Edginton
- School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada.
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Tauzin M, Tréluyer JM, Nabbout R, Billette de Villemeur T, Desguerre I, Aboura R, Gana I, Zheng Y, Benaboud S, Bouazza N, Chenevier-Gobeaux C, Freihuber C, Hirt D. Dosing Recommendations for Lamotrigine in Children: Evaluation Based on Previous and New Population Pharmacokinetic Models. J Clin Pharmacol 2020; 61:677-687. [PMID: 33244764 DOI: 10.1002/jcph.1791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/19/2020] [Indexed: 12/30/2022]
Abstract
Lamotrigine is a broad-spectrum antiepileptic drug with high interindividual variability in serum concentrations in children. The aims of this study were to evaluate the predictive performance of pediatric population pharmacokinetic (PPK) models published on lamotrigine, to build a new model with our monitoring data and to evaluate the current recommended doses. A validation cohort included patients treated with lamotrigine who had a serum level assayed during therapeutic drug monitoring (TDM). PPK models published in the literature were first applied to the validation cohort. We assessed their predictive performance using mean prediction errors, root mean squared errors, and visual predictive checks. A new model was then built using the data. Dose simulations were performed to evaluate the doses recommended. We included 270 lamotrigine concentrations ranging from 0.5 to 17.9 mg/L from 175 patients. The median (range) age and weight were 11.8 years (0.8-18 years) and 32.7 kg (8-110 kg). We tested 6 PPK models; most had acceptable bias and precision but underestimated the variability of the cohort. We built a 1-compartment model with first-order absorption and elimination, allometric scaling, and effects of inhibitor and inducer comedications. In our cohort, 22.6% of trough concentrations were below 2.5 mg/L. In conclusion, we proposed a PPK model that can be used for TDM of lamotrigine in children. In our population, a high percentage of children had low trough concentrations of lamotrigine. As the intervals of recommended doses are large, we suggest aiming at the higher range of doses to reach the target concentration.
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Affiliation(s)
- Manon Tauzin
- Service de Pharmacologie Clinique, Hôpital Cochin, APHP, Paris, France
- Réanimation néonatale et néonatologie, Centre Hospitalier Intercommunal de Créteil, Créteil, France
| | - Jean-Marc Tréluyer
- Service de Pharmacologie Clinique, Hôpital Cochin, APHP, Paris, France
- EA 7323, Université Paris Descartes Sorbonne Paris Cité, Paris, France
- Unité de recherche Clinique, Hôpital Universitaire Necker-Enfants Malades, APHP, Université Paris Descartes, Paris, France
| | - Rima Nabbout
- Centre de référence épilepsies rares, Service de Neurologie pédiatrique, Hôpital Necker Enfants Malades, APHP, Paris, France
| | - Thierry Billette de Villemeur
- Sorbonne Université, UPMC, GRC ConCer-LD and AP-HP, Hôpital Trousseau, Service de Neuropédiatrie - Pathologie du développement, Centre de référence des déficits intellectuels de causes rares, Paris, France
| | - Isabelle Desguerre
- Centre de référence épilepsies rares, Service de Neurologie pédiatrique, Hôpital Necker Enfants Malades, APHP, Paris, France
| | - Radia Aboura
- Service de Pharmacologie Clinique, Hôpital Cochin, APHP, Paris, France
| | - Ines Gana
- Service de Pharmacologie Clinique, Hôpital Cochin, APHP, Paris, France
| | - Yi Zheng
- Service de Pharmacologie Clinique, Hôpital Cochin, APHP, Paris, France
| | - Sihem Benaboud
- Service de Pharmacologie Clinique, Hôpital Cochin, APHP, Paris, France
- EA 7323, Université Paris Descartes Sorbonne Paris Cité, Paris, France
| | - Naim Bouazza
- EA 7323, Université Paris Descartes Sorbonne Paris Cité, Paris, France
| | - Camille Chenevier-Gobeaux
- Service de Diagnostic Biologique Automatisé, Hôpital Cochin, Hôpitaux Universitaires Paris Centre (HUPC), Assistance Publique des Hôpitaux de Paris (APHP), Paris, France
| | - Cécile Freihuber
- Sorbonne Université, UPMC, GRC ConCer-LD and AP-HP, Hôpital Trousseau, Service de Neuropédiatrie - Pathologie du développement, Centre de référence des déficits intellectuels de causes rares, Paris, France
| | - Déborah Hirt
- Service de Pharmacologie Clinique, Hôpital Cochin, APHP, Paris, France
- EA 7323, Université Paris Descartes Sorbonne Paris Cité, Paris, France
- Inserm 1018 CESP, Hôpital Bicêtre, Le Kremlin-Bicêtre, France
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Prediction of Clearance in Children from Adults Following Drug-Drug Interaction Studies: Application of Age-Dependent Exponent Model. Drugs R D 2020; 20:47-54. [PMID: 32056156 PMCID: PMC7067713 DOI: 10.1007/s40268-020-00295-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Background and Objective Pharmacokinetic drug–drug interaction (DDI) studies are conducted in adult subjects during drug development but there are limited studies that have characterized pharmacokinetic DDI studies in children. The objective of this study was to evaluate if the DDI clearance values from adults can be allometrically extrapolated from adults to children. Methods Fifteen drugs were included in this study and the age of the children ranged from premature neonates to adolescents (30 observations across the age groups). The age-dependent exponent (ADE) model was used to predict the clearance of drugs in children from adults following DDI studies. Results The prediction error of drug clearances following DDIs in children ranged from 4 to 67%. Of 30 observations, 17 (57%) and 27 (90%) observations had a prediction error ≤ 30% and ≤ 50%, respectively. Conclusion This study indicates that it is possible to predict the clearance of drugs with reasonable accuracy in children from adults following DDI studies using an ADE model. The method is simple, robust, and reliable and can replace other complex empirical models.
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Fekete S, Hiemke C, Gerlach M. Dose-Related Concentrations of Neuroactive/Psychoactive Drugs Expected in Blood of Children and Adolescents. Ther Drug Monit 2020; 42:315-324. [PMID: 32195989 DOI: 10.1097/ftd.0000000000000685] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
PURPOSE Therapeutic drug monitoring is highly recommended for children and adolescents treated with neurotropic/psychotropic drugs. For interpretation of therapeutic drug monitoring results, drug concentrations (C/D) expected in a "normal" population are helpful to identify pharmacokinetic abnormalities or nonadherence. Using dose-related concentration (DRC) factors obtained from pharmacokinetic data, C/D ranges expected under steady state can be easily calculated by multiplication of DRC by the daily dose. DRC factors, however, are defined only for adults so far. Therefore, it was the aim of this study to estimate DRC factors for children and adolescents and compare them with those of adults. METHODS To obtain pharmacokinetic data (apparent total clearance of drugs from plasma after oral administration, elimination half-life, area under the curve, and minimum serum drug concentration) from children and adolescents treated with psychotropic drugs, a systematic review of published literature was performed, and the pharmaceutical companies that market these drugs were contacted. Available information was used for the calculation of DRC factors. RESULTS Fourteen of 26 drugs had similar DRC factors to those reported for adults; 8 and 4 had higher and lower factors, respectively. The antidepressants citalopram, clomipramine, fluvoxamine, and imipramine and the antipsychotics haloperidol and olanzapine showed higher DRC factors than those calculated for adults. The DRC factors of amphetamine and methylphenidate were higher in children (6-12 years) but not in adolescents (13-17 years). On the contrary, the antipsychotic quetiapine and the mood-stabilizing antiepileptics lamotrigine, oxcarbazepine, and topiramate showed lower DRC factors than those calculated for adults. CONCLUSIONS It was concluded that concentrations of neuroactive/psychoactive drugs to be expected in blood for a given dose may differ between adults and children or adolescents, most probably owing to age-dependent differences in the elimination of these drugs.
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Affiliation(s)
- Stefanie Fekete
- Department Child and Adolescent Psychiatry, University Hospital of Würzburg, Würzburg; and
| | - Christoph Hiemke
- Department of Psychiatry and Psychotherapy, University Medical Center of Mainz, Mainz, Germany
| | - Manfred Gerlach
- Department Child and Adolescent Psychiatry, University Hospital of Würzburg, Würzburg; and
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A repository of protein abundance data of drug metabolizing enzymes and transporters for applications in physiologically based pharmacokinetic (PBPK) modelling and simulation. Sci Rep 2019; 9:9709. [PMID: 31273226 PMCID: PMC6609630 DOI: 10.1038/s41598-019-45778-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 06/04/2019] [Indexed: 01/09/2023] Open
Abstract
Population factors such as age, gender, ethnicity, genotype and disease state can cause inter-individual variability in pharmacokinetic (PK) profile of drugs. Primarily, this variability arises from differences in abundance of drug metabolizing enzymes and transporters (DMET) among individuals and/or groups. Hence, availability of compiled data on abundance of DMET proteins in different populations can be useful for developing physiologically based pharmacokinetic (PBPK) models. The latter are routinely employed for prediction of PK profiles and drug interactions during drug development and in case of special populations, where clinical studies either are not feasible or have ethical concerns. Therefore, the main aim of this work was to develop a repository of literature-reported DMET abundance data in various human tissues, which included compilation of information on sample size, technique(s) involved, and the demographic factors. The collation of literature reported data revealed high inter-laboratory variability in abundance of DMET proteins. We carried out unbiased meta-analysis to obtain weighted mean and percent coefficient of variation (%CV) values. The obtained %CV values were then integrated into a PBPK model to highlight the variability in drug PK in healthy adults, taking lamotrigine as a model drug. The validated PBPK model was extrapolated to predict PK of lamotrigine in paediatric and hepatic impaired populations. This study thus exemplifies importance of the DMET protein abundance database, and use of determined values of weighted mean and %CV after meta-analysis in PBPK modelling for the prediction of PK of drugs in healthy and special populations.
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Koristkova B, Grundmann M, Brozmanova H, Kacirova I. Lamotrigine drug interactions in combination therapy and the influence of therapeutic drug monitoring on clinical outcomes in paediatric patients. Basic Clin Pharmacol Toxicol 2019; 125:26-33. [DOI: 10.1111/bcpt.13203] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 01/15/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Blanka Koristkova
- Department of Clinical Pharmacology, Faculty of Medicine; University of Ostrava; Ostrava Czech Republic
- Department of Clinical Pharmacology; Department of Laboratory Diagnostics; University Hospital Ostrava; Ostrava Czech Republic
| | - Milan Grundmann
- Department of Clinical Pharmacology, Faculty of Medicine; University of Ostrava; Ostrava Czech Republic
| | - Hana Brozmanova
- Department of Clinical Pharmacology, Faculty of Medicine; University of Ostrava; Ostrava Czech Republic
- Department of Clinical Pharmacology; Department of Laboratory Diagnostics; University Hospital Ostrava; Ostrava Czech Republic
| | - Ivana Kacirova
- Department of Clinical Pharmacology, Faculty of Medicine; University of Ostrava; Ostrava Czech Republic
- Department of Clinical Pharmacology; Department of Laboratory Diagnostics; University Hospital Ostrava; Ostrava Czech Republic
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Verrotti A, Iapadre G, Di Donato G, Di Francesco L, Zagaroli L, Matricardi S, Belcastro V, Iezzi ML. Pharmacokinetic considerations for anti-epileptic drugs in children. Expert Opin Drug Metab Toxicol 2019; 15:199-211. [PMID: 30689454 DOI: 10.1080/17425255.2019.1575361] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Epilepsy is a chronic and debilitating neurological disease, with a peak of incidence in the first years of life. Today, the vast armamentarium of antiepileptic drugs (AEDs) available make even more challenging to select the most appropriate AED and establish the most effective dosing regimen. In fact, AEDs pharmacokinetics is under the influence of important age-related factors which cannot be ignored. Areas covered: Physiological changes occurring during development age (different body composition, immature metabolic patterns, reduced renal activity) can significantly modify the pharmacokinetic profile of AEDs (adsorption, volume of distribution, half-life, clearance), leading to an altered treatment response. We reviewed the main pharmacokinetic characteristics of AEDs used in children, focusing on age-related factors which are of relevance when treating this patient population. Expert opinion: To deal with this pharmacokinetic variability, physicians have at their disposal two tools: 1) therapeutic drug concentration monitoring, which may help to set the optimal therapeutic regimen for each patient and to monitor eventual fluctuation, and 2) the use of extended-release drug formulations, when available. In the next future, the development of 'ad-hoc' electronic dashboard systems will represent relevant decision-support tools making the AED therapy even more individualized and precise, especially in children.
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Affiliation(s)
- Alberto Verrotti
- a Department of Pediatrics , University of L'Aquila , L'Aquila , Italy
| | - Giulia Iapadre
- a Department of Pediatrics , University of L'Aquila , L'Aquila , Italy
| | - Giulia Di Donato
- a Department of Pediatrics , University of L'Aquila , L'Aquila , Italy
| | | | - Luca Zagaroli
- a Department of Pediatrics , University of L'Aquila , L'Aquila , Italy
| | - Sara Matricardi
- b Child Neurology and Psychiatry Unit , Children's Hospital G. Salesi , Ancona , Italy
| | | | - Maria Laura Iezzi
- a Department of Pediatrics , University of L'Aquila , L'Aquila , Italy
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12
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Abstract
Childhood absence epilepsy (CAE) is a common pediatric epilepsy syndrome with distinct seizure semiology, electroencephalography (EEG) features, and treatment. A diagnosis of CAE can be obtained during an office visit with a careful history, physical exam including prolonged hyperventilation, and a routine EEG. The treatment of choice for CAE with absence seizures only is ethosuximide. Valproic acid and lamotrigine are also effective treatments for many patients, but when compared to ethosuximide, valproic acid has more adverse effects and lamotrigine is less effective. Attention to predictors of response to treatment, including clinical, electrographic, and genetic factors, is increasing. Refractory CAE occurs in fewer than half of patients, and treatment strategies are available, though efficacy data are lacking. Careful assessment and treatment of psychosocial comorbidities is essential in caring for patients with CAE.
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Affiliation(s)
- Sudha Kilaru Kessler
- Perelman School of Medicine, Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA.
| | - Emily McGinnis
- Kaiser Permanente Los Angeles Medical Center, Los Angeles, CA USA
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13
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A Physiologically Based Pharmacokinetic Model for Optimally Profiling Lamotrigine Disposition and Drug–Drug Interactions. Eur J Drug Metab Pharmacokinet 2018; 44:389-408. [DOI: 10.1007/s13318-018-0532-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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14
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Iapadre G, Balagura G, Zagaroli L, Striano P, Verrotti A. Pharmacokinetics and Drug Interaction of Antiepileptic Drugs in Children and Adolescents. Paediatr Drugs 2018; 20:429-453. [PMID: 30003498 DOI: 10.1007/s40272-018-0302-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Selecting the most appropriate antiepileptic drug (AED) or combination of drugs for each patient and identifying the most suitable therapeutic regimen for their needs is increasingly challenging, especially among pediatric populations. In fact, the pharmacokinetics of several drugs vary widely in children with epilepsy because of age-related factors, which can influence the absorption, distribution, metabolism, and elimination of the pharmacological agent. In addition, individual factors, such as seizure type, associated comorbidities, individual pharmacokinetics, and potential drug interactions, may contribute to large fluctuations in serum drug concentrations and, therefore, clinical response. Therapeutic drug concentration monitoring (TDM) is an essential tool to deal with this complexity, enabling the definition of individual therapeutic concentrations and adaptive control of dosing to minimize drug interactions and prevent loss of efficacy or toxicity. Moreover, pharmacokinetic/pharmacodynamic modelling integrated with dashboard systems have recently been tested in antiepileptic therapy, although more clinical trials are required to support their use in clinical practice. We review the mechanism of action, pharmacokinetics, drug-drug interactions, and safety/tolerability profiles of the main AEDs currently used in children and adolescents, paying particular regard to issues of relevance when treating this patient population. Indications for TDM are provided for each AED as useful support to the clinical management of pediatric patients with epilepsy by optimizing pharmacological therapy.
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Affiliation(s)
- Giulia Iapadre
- Department of Pediatrics, University of L'Aquila, Via Vetoio, 1. Coppito, L'Aquila, Italy
| | - Ganna Balagura
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Opthalmology, Genetics, Maternal and Child Health, University of Genoa, "G. Gaslini" Institute, Genoa, Italy
| | - Luca Zagaroli
- Department of Pediatrics, University of L'Aquila, Via Vetoio, 1. Coppito, L'Aquila, Italy
| | - Pasquale Striano
- Pediatric Neurology and Muscular Diseases Unit, Department of Neurosciences, Rehabilitation, Opthalmology, Genetics, Maternal and Child Health, University of Genoa, "G. Gaslini" Institute, Genoa, Italy
| | - Alberto Verrotti
- Department of Pediatrics, University of L'Aquila, Via Vetoio, 1. Coppito, L'Aquila, Italy.
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15
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Comparison of the QMS Analyzer With HPLC-UV for the Quantification of Lamotrigine Concentrations in Human Plasma Samples. Ther Drug Monit 2015; 37:689-94. [DOI: 10.1097/ftd.0000000000000202] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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16
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Italiano D, Perucca E. Clinical pharmacokinetics of new-generation antiepileptic drugs at the extremes of age: an update. Clin Pharmacokinet 2014; 52:627-45. [PMID: 23640503 DOI: 10.1007/s40262-013-0067-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Epilepsies occur across the entire age range, and their incidence peaks in the first years of life and in the elderly. Therefore, antiepileptic drugs (AEDs) are commonly used at the extremes of age. Rational prescribing in these age groups requires not only an understanding of the drugs' pharmacodynamic properties, but also careful consideration of potential age-related changes in their pharmacokinetic profile. The present article, which updates a review published in 2006 in this journal, focuses on recent findings on the pharmacokinetics of new-generation AEDs in neonates, infants, children, and the elderly. Significant new information on the pharmacokinetics of new AEDs in the perinatal period has been acquired, particularly for lamotrigine and levetiracetam. As a result of slow maturation of the enzymes involved in glucuronide conjugation, lamotrigine elimination occurs at a particularly slow rate in neonates, and becomes gradually more efficient during the first months of life. In the case of levetiracetam, elimination occurs primarily by renal excretion and is also slow at birth, but drug clearance increases rapidly thereafter and can even double within 1 week. In general, infants older than 2-3 months and children show higher drug clearance (normalized for body weight) than adults. This pattern was confirmed in recent studies that investigated the pediatric pharmacokinetics of several new AEDs, including levetiracetam, rufinamide, stiripentol, and eslicarbazepine acetate. At the other extreme of age, in the elderly, drug clearance is generally reduced compared with younger adults because of less efficient drug-metabolizing activity, decreased renal function, or both. This general pattern, described previously for several AEDs, was confirmed in recent studies on the effect of old age on the clearance of felbamate, levetiracetam, pregabalin, lacosamide, and retigabine. For those drugs which are predominantly eliminated by renal excretion, aging-related pharmacokinetic changes could be predicted by measuring creatinine clearance (CLCR). Overall, most recent findings confirm that age is a major factor influencing the pharmacokinetic profile of AEDs. However, pharmacokinetic variability at any age can be considerable, and the importance of other factors should not be disregarded. These include genetic factors, co-morbidities, and drug interactions, particularly those caused by concomitantly administered AEDs which induce or inhibit drug-metabolizing enzymes.
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Affiliation(s)
- Domenico Italiano
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
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17
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Malik S, Arif H, Hirsch LJ. Lamotrigine and its applications in the treatment of epilepsy and other neurological and psychiatric disorders. Expert Rev Neurother 2014; 6:1609-27. [PMID: 17144777 DOI: 10.1586/14737175.6.11.1609] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Lamotrigine is a broad-spectrum antiepileptic drug, initially approved in 1994 for the adjunctive treatment of partial seizures in adults and for the generalized seizures of Lennox-Gastaut syndrome in pediatric (>2 years old) and adult populations. Its role in the treatment of bipolar disorder type I has also been well established. In addition, lamotrigine has been successfully used for the management of other neurological conditions such as migraines and neuropathic pain, and preliminary data show promising results. It has favorable pharmacokinetic properties and is generally well tolerated. The small risk of serious skin rash can be minimized with slow titration of the drug and dose adjustment with concomitant medications. Lamotrigine has demonstrated particular benefit in the treatment of women and elderly patients with epilepsy.
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Affiliation(s)
- Sheetal Malik
- Comprehensive Epilepsy Center, Columbia University Neurological Institute, Box NI-135, 710 West 168th Street, 7th Floor, New York, NY 10032, USA.
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18
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Brzaković B, Vučićević K, Kovačević SV, Miljković B, Prostran M, Martinović Ž, Pokrajac M. Pharmacokinetics of lamotrigine in paediatric and young adult epileptic patients--nonlinear mixed effects modelling approach. Eur J Clin Pharmacol 2013; 70:179-85. [PMID: 24240511 DOI: 10.1007/s00228-013-1606-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 10/23/2013] [Indexed: 11/28/2022]
Abstract
PURPOSE The purpose of the study was to examine and describe adjunctive lamotrigine (LTG) pharmacokinetics in paediatric and young adult patients using a nonlinear mixed effects modelling (NONMEM) approach. METHODS The study included 53 patients (age range 3-35 years) who were concomitantly treated with carbamazepine (CBZ) and/or valproic acid (VPA). A total of 70 blood samples corresponding to trough levels were available for analysis. Data were modelled, and the final model was evaluated using NONMEM and auxiliary software tools. RESULTS The final LTG population model included the effects of concomitant drugs and patient's weight (WT) which stratified the population into three groups: ≤25 kg, >25 to <60 kg and ≥60 kg. Based on the final model, the estimated LTG oral clearance (CL/F) for a typical patient weighing ≤25 kg, >25 to <60 kg or ≥60 kg who was concomitantly treated with CBZ was estimated to be 3.28, 4.23, or 7.15 l/h, respectively. If a patient was concomitantly treated with CBZ + VPA, the CL/F decreased on average by 69.5 % relative to LTG + CBZ co-therapy. VPA was found to decrease the LTG CL/F by 87.6 % compared to co-therapy with only CBZ. CONCLUSION The LTG population pharmacokinetic model developed in this study may be a reliable method for individualising the LTG dosing regimen in paediatric and young adult patients on combination therapy during therapeutic drug monitoring.
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Affiliation(s)
- Branka Brzaković
- Medicines and Medical Devices Agency of Serbia, Belgrade, Serbia
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19
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Dynamic time course of typical childhood absence seizures: EEG, behavior, and functional magnetic resonance imaging. J Neurosci 2010; 30:5884-93. [PMID: 20427649 DOI: 10.1523/jneurosci.5101-09.2010] [Citation(s) in RCA: 211] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Absence seizures are 5-10 s episodes of impaired consciousness accompanied by 3-4 Hz generalized spike-and-wave discharge on electroencephalography (EEG). The time course of functional magnetic resonance imaging (fMRI) changes in absence seizures in relation to EEG and behavior is not known. We acquired simultaneous EEG-fMRI in 88 typical childhood absence seizures from nine pediatric patients. We investigated behavior concurrently using a continuous performance task or simpler repetitive tapping task. EEG time-frequency analysis revealed abrupt onset and end of 3-4 Hz spike-wave discharges with a mean duration of 6.6 s. Behavioral analysis also showed rapid onset and end of deficits associated with electrographic seizure start and end. In contrast, we observed small early fMRI increases in the orbital/medial frontal and medial/lateral parietal cortex >5 s before seizure onset, followed by profound fMRI decreases continuing >20 s after seizure end. This time course differed markedly from the hemodynamic response function (HRF) model used in conventional fMRI analysis, consisting of large increases beginning after electrical event onset, followed by small fMRI decreases. Other regions, such as the lateral frontal cortex, showed more balanced fMRI increases followed by approximately equal decreases. The thalamus showed delayed increases after seizure onset followed by small decreases, most closely resembling the HRF model. These findings reveal a complex and long-lasting sequence of fMRI changes in absence seizures, which are not detectable by conventional HRF modeling in many regions. These results may be important mechanistically for seizure initiation and termination and may also contribute to changes in EEG and behavior.
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20
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Bentué-Ferrer D, Tribut O, Verdier MC. Suivi thérapeutique pharmacologique de la lamotrigine. Therapie 2010; 65:39-46. [DOI: 10.2515/therapie/2009063] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 12/04/2009] [Accepted: 12/01/2009] [Indexed: 11/20/2022]
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21
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Pharmacokinetics and Therapeutic Drug Monitoring of Psychotropic Drugs in Pediatrics. Ther Drug Monit 2009; 31:283-318. [DOI: 10.1097/ftd.0b013e31819f3328] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Development of an ultra-performance liquid chromatography–tandem mass spectrometry micromethod for quantification of lamotrigine in human plasma and its use in a bioequivalence trial. Bioanalysis 2009; 1:47-55. [DOI: 10.4155/bio.09.8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: The aim of the present work was to develop a chromatographic technique coupled with mass spectrometry for the measurement of lamotrigine in plasma. Lamotrigine and guanabenz (internal standard) were measured by selected reaction monitoring. The method was validated and applied in a bioequivalence trial on 26 female volunteers. Lamotrigine chewable tablets (100 mg) were administered and monitored for up to 96 h. Results: The method was linear between 0.05 and 5.0 µg/ml, with acceptable stability, accuracy and precision. Mean maximum plasma concentration was 1.37 µg/ml and was reached at 1.6 h postdose. Elimination half-life was 32.7 h. Conclusion: Lamotrigine tablets were bioequivalent. Ultra-performance liquid chromatography with tandem mass spectrometry represents a powerful tool in terms of sensitivity, specificity and high-throughput analysis.
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23
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Abstract
Epilepsy is common in the pediatric population. Nine second-generation antiepileptic drugs have been approved in the US for use in epilepsy over the past 15 years: felbamate, gabapentin, lamotrigine, topiramate, tiagabine, levetiracetam, oxcarbazepine, zonisamide, and pregabalin. Their use in pediatric patients is fairly widespread, despite most of these agents not having US FDA indications for use. Felbamate and gabapentin were the first two second-generation antiepileptic drugs to be approved in the US. Felbamate use has been limited because of the occurrence of hepatotoxicity and aplastic anemia. Although gabapentin is a fairly well tolerated antiepileptic drug, its use has also been limited as a result of inconsistent efficacy and concern about seizure exacerbation. Lamotrigine and topiramate are broad-spectrum antiepileptic drugs with efficacy in a wide variety of seizure types. Both agents have some tolerability concerns: rash with lamotrigine and neuropsychiatric events with topiramate. There are very little data on tiagabine use in children, but this agent appears to be effective and to have a good tolerability profile. Levetiracetam is a second-generation antiepileptic agent that is available intravenously. Considering its good efficacy, fast onset of action, and low incidence of serious adverse effects, its use in the acute setting could potentially increase. Oxcarbazepine and zonisamide have been relatively well studied in pediatric seizure patients, including use as monotherapy. Both agents have demonstrated good efficacy and tolerability for patients as young as 1 month old. Vigabatrin and rufinamide are currently not available in the US, but have been shown to have some success in other countries. Pregabalin is the newest antiepileptic agent, but lacks pediatric data currently.
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Affiliation(s)
- Allison M Chung
- Harrison School of Pharmacy, Pharmacy Practice, Auburn University, Auburn, Alabama, USA.
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24
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Glauser TA, Mitchell WG, Weinstock A, Bebin M, Chen D, Coupez R, Stockis A, Lu ZS. Pharmacokinetics of Levetiracetam in Infants and Young Children with Epilepsy. Epilepsia 2007; 48:1117-22. [PMID: 17442002 DOI: 10.1111/j.1528-1167.2007.01090.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE To assess the single-dose pharmacokinetics of levetiracetam and its major metabolite ucb L057 in infants and young children with epilepsy. METHODS Eligible patients with a stable regimen of antiepileptic medications received a single oral dose of levetiracetam 20 mg/kg administered as a 10% oral solution followed by a 24-hour pharmacokinetic evaluation. RESULTS Thirteen subjects (age 2.3-46.2 months) enrolled and received levetiracetam; 12 provided evaluable pharmacokinetic data. Levetiracetam was rapidly absorbed and reached peak plasma concentration (t(max)) 1.4 +/- 0.9 hours after dosing. The mean half-life (t(1/2)) of levetiracetam was 5.3 +/- 1.3 hours, and the apparent clearance was 1.46 +/- 0.42 mL/min/kg. Graphical differences were observed among three age subgroups (1 to <6 months, 6 to <24 months, and 24 to <48 months); however, statistical analysis was limited due to each subgroup's small sample size. No significant gender differences were detected. Treatment-emergent adverse events were seen in three patients (23.1%) but were not considered to be related to levetiracetam. CONCLUSIONS The mean t(1/2) of levetiracetam was shorter and its apparent clearance was more rapid for infants and young children than that previously reported for adults. When determining dosage, age-dependent drug clearance should be considered; these findings suggest that a larger dose of levetiracetam (corrected for body weight) needs to be considered for infants and young children with epilepsy than that given to adults with epilepsy. A single dose of levetiracetam was well tolerated in this study population.
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Affiliation(s)
- Tracy A Glauser
- Children's Hospital Medical Center, Department of Neurology, Cincinnati, Ohio 45229, USA.
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25
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Reimers A, Skogvoll E, Sund JK, Spigset O. Lamotrigine in children and adolescents: the impact of age on its serum concentrations and on the extent of drug interactions. Eur J Clin Pharmacol 2007; 63:687-92. [PMID: 17497143 DOI: 10.1007/s00228-007-0308-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Accepted: 04/02/2007] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the impact of age and co-treatment with other drugs on the serum concentrations of lamotrigine in children and adolescents. METHODS A review of routine serum concentration measurements of lamotrigine performed in our laboratory yielded a total of 744 serum samples from 296 subjects (110 males, 186 females, age: 2-19 years) suitable for statistical analysis. The primary outcome variable was the dose-corrected lamotrigine serum concentration, expressed as the lamotrigine concentration/dose (C/D) ratio. A linear mixed model that allowed multiple observations from the same patient was used to identify and quantify the effect of factors influencing the lamotrigine C/D ratio. RESULTS According to the model, the lamotrigine C/D ratio decreases by 6% per year of age. Valproate and levetiracetam were found to raise the lamotrigine C/D ratio, whereas the following co-medications reduced it: carbamazepine, clobazam, fluoxetine, clonazepam and ethinyl estradiol. The effect of carbamazepine decreased with increasing age. No gender difference was detected. CONCLUSIONS Age is an important factor with respect to the pharmacokinetics and the extent of drug interactions of lamotrigine in children and adolescents. In this population, older individuals will need higher doses than younger ones in order to achieve the same serum concentrations.
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Affiliation(s)
- Arne Reimers
- Department of Clinical Pharmacology, St. Olavs University Hospital, 7006 Trondheim, Norway.
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Abstract
Psychopharmacologic treatment in pediatric critical care requires a careful child or adolescent psychiatric evaluation, including a thorough review of the history of present illness or injury, any current or pre-existing psychiatric disorder, past history, and laboratory studies. Although there is limited evidence to guide psychopharmacologic practice in this setting, psychopharmacologic treatment is increasing in critical care, with known indications for treatment, benefits, and risks; initial dosing guidelines; and best practices. Treatment is guided by the knowledge bases in pediatric physiology, psycho-pharmacology, and treatment of critically ill adults. Pharmacologic considerations include pharmacokinetic and pharmcodynamic aspects of specific drugs and drug classes, in particular elimination half-life, developmental considerations, drug interactions, and adverse effects. Evaluation and management of pain is a key initial step, as pain may mimic psychiatric symptoms and its effective treatment can ameliorate them. Patient comfort and safety are primary objectives for children who are acutely ill and who will survive and for those who will not. Judicious use of psychopharmacolgic agents in pediatric critical care using the limited but growing evidence base and a clinical best practices collaborative approach can reduce anxiety,sadness, disorientation, and agitation; improve analgesia; and save lives of children who are suicidal or delirious. In addition to pain, other disorders or indications for psychopharmacologic treatment are affective disorders;PTSD; post-suicide attempt patients; disruptive behavior disorders (especially ADHD); and adjustment, developmental, and substance use disorders. Treating children who are critically ill with psychotropic drugs is an integral component of comprehensive pediatric critical care in relieving pain and delirium; reducing inattention or agitation or aggressive behavior;relieving acute stress, anxiety, or depression; and improving sleep and nutrition. In palliative care, psychopharmacology is integrated with psychologicapproaches to enhance children's comfort at the end of life. Defining how best to prevent the adverse consequences of suffering and stress in pediatric critical care is a goal for protocols and for new psychopharmacologic research [23,153].
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27
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Abstract
Newer generation antiepileptic drugs (AEDs) are increasingly used to treat epilepsies in infants, children, and the elderly. For rational prescribing in these populations, it is essential to understand the pharmacokinetic changes that occur during development and aging. Data obtained in recent years indicate that the apparent oral clearance (CL/F) of lamotrigine, topiramate, levetiracetam, oxcarbazepine, gabapentin, tiagabine, zonisamide, vigabatrin, and felbamate is considerably higher in children than in adults,the magnitude of the difference being on average in the order of 20%to 120%, depending on the drug and the age distribution of the assessed population. Information on the pharmacokinetics of these drugs in newborns is completely lacking or very sparse. Studies in the elderly have demonstrated that significant pharmacokinetic changes also occur at the other extreme of age. On average, CL/F values of newer generation AEDs have been found to be reduced by 10% to 50% compared with those found in young or middle-aged adults. These pharmacokinetic changes are clinically important and con-tribute to age-related differences in dosage requirements.
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Affiliation(s)
- Emilio Perucca
- Clinical Pharmacology Unit, Department of Internal Medicine and Therapeutics, University of Pavia, Italy.
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28
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Abstract
In recent years, several new-generation antiepileptic drugs (AEDs) have been introduced in clinical practice. These agents, which include felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, pregabalin, tiagabine, topiramate, vigabatrin and zonisamide, are being increasingly used in the treatment of epilepsy at the extremes of age. For a rational prescribing of these drugs in specific age groups, major pharmacokinetic changes that occur during development and aging need to be taken into consideration. A review of available evidence indicates that the apparent oral clearance (CL/F) of new-generation AEDs in children is increased by 20-170% (depending on the type of drug and characteristics of the patients studied) compared with adults, with the highest CL/F values usually being observed in the youngest age groups. These findings do not necessarily apply to the first weeks of life, when drug eliminating capacity is still undergoing maturation, as in the case of lamotrigine for which preliminary data suggest that CL/F in neonates aged <2 months can be much lower than in infants aged 2-12 months. At the other extreme of age, in the elderly, CL/F is almost invariably reduced (on average by 10-50%) compared with values found in non-elderly adults. Age-related CL/F changes, together with the large interindividual pharmacokinetic variability, contribute to the need for individualised dosage requirements in these patients. Measurement of serum drug concentrations can be useful as an aid to dosage individualization in these age groups but interpretation of therapeutic drug monitoring data should also take into account the possibility of age-related changes in pharmacodynamic sensitivity and, for neonates and the elderly, alterations in drug binding to serum proteins.
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Affiliation(s)
- Emilio Perucca
- Clinical Pharmacology Unit, Department of Internal Medicine and Therapeutics, University of Pavia, Pavia, Italy.
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29
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Abstract
A new generation of antiepileptic drugs (AEDs) has reached the market in recent years with ten new compounds: felbamate, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, pregabalin, tiagabine, topiramate, vigabatrin and zonisamide. The newer AEDs in general have more predictable pharmacokinetics than older AEDs such as phenytoin, carbamazepine and valproic acid (valproate sodium), which have a pronounced inter-individual variability in their pharmacokinetics and a narrow therapeutic range. For these older drugs it has been common practice to adjust the dosage to achieve a serum drug concentration within a predefined 'therapeutic range', representing an interval where most patients are expected to show an optimal response. However, such ranges must be interpreted with caution, since many patients are optimally treated when they have serum concentrations below or above the suggested range. It is often said that there is less need for therapeutic drug monitoring (TDM) with the newer AEDs, although this is partially based on the lack of documented correlation between serum concentration and drug effects. Nevertheless, TDM may be useful despite the shortcomings of existing therapeutic ranges, by utilisation of the concept of 'individual reference concentrations' based on intra-individual comparisons of drug serum concentrations. With this concept, TDM may be indicated regardless of the existence or lack of a well-defined therapeutic range. The ten newer AEDs all have different pharmacological properties, and therefore, the usefulness of TDM for these drugs has to be assessed individually. For vigabatrin, a clear relationship between drug concentration and clinical effect cannot be expected because of its unique mode of action. Therefore, TDM of vigabatrin is mainly to check compliance. The mode of action of the other new AEDs would not preclude the applicability of TDM. For the prodrug oxcarbazepine, TDM is also useful, since the active metabolite licarbazepine is measured. For drugs that are eliminated renally completely unchanged (gabapentin, pregabalin and vigabatrin) or mainly unchanged (levetiracetam and topiramate), the pharmacokinetic variability is less pronounced and more predictable. However, the dose-dependent absorption of gabapentin increases its pharmacokinetic variability. Drug interactions can affect topiramate concentrations markedly, and individual factors such as age, pregnancy and renal function will contribute to the pharmacokinetic variability of all renally eliminated AEDs. For those of the newer AEDs that are metabolised (felbamate, lamotrigine, oxcarbazepine, tiagabine and zonisamide), pharmacokinetic variability is just as relevant as for many of the older AEDs. Therefore, TDM is likely to be useful in many clinical settings for the newer AEDs. The purpose of the present review is to discuss individually the potential value of TDM of these newer AEDs, with emphasis on pharmacokinetic variability.
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30
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Ferrari AR, Guerrini R, Gatti G, Alessandrì MG, Bonanni P, Perucca E. Influence of Dosage, Age, and Co-medication on Plasma Topiramate Concentrations in Children and Adults with Severe Epilepsy and Preliminary Observations on Correlations with Clinical Response. Ther Drug Monit 2003; 25:700-8. [PMID: 14639056 DOI: 10.1097/00007691-200312000-00008] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The influence of dosage, age, and co-medication on plasma topiramate (TPM) concentrations at steady state was investigated in 51 patients aged 3 to 30 years. All patients had chronic active epilepsy, and most were receiving concomitant medication with enzyme-inducing anticonvulsants (carbamazepine and phenobarbital). Plasma TPM concentrations were determined by a specific immunoassay in samples obtained before the morning dose. Thirty-five patients could be evaluated prospectively at different dose levels, and the relationship between plasma TPM concentration and dosage was linear over the assessed dose range (1.8 to 10.0 mg/kg) both in adults and in children. The influence of age on pharmacokinetic parameters could be assessed only for the 42 patients co-medicated with enzyme inducers. In these patients dose-normalized plasma TPM concentrations correlated positively with age (r = 0.59, P < 0.0001), where apparent oral clearance values (CL/F) were inversely related to age (r = 0.73, P < 0.0001). In particular, CL/F values in children aged less than 10 years (112 +/- 82 mL/kg/h, mean +/- SD, n = 14) were almost three times as high as those observed in patients aged >15 to 30 years (42 +/- 16 mL/kg/h, n = 17), whereas the CL/F value in children aged 10 to 15 years (66 +/- 22 mL/kg/h, n = 11) was intermediate between those found in the two other age groups. Patients not receiving enzyme-inducing AEDs showed lower CL/F values than did age- and gender-matched patients on enzyme-inducing co-medication. A preliminary evaluation of the relationship between plasma TPM concentration and therapeutic response could be made in 41 patients. No significant difference in drug concentration was detected between patients showing a greater than 50% reduction in seizure frequency compared with baseline (5.9 +/- 2.2 micrograms/mL, n = 30) and those having no clinical improvement (5.2 +/- 2.2 micrograms/mL, n = 11). Likewise, there was no consistent relationship between plasma TPM concentration and appearance of adverse effects. These results indicate that plasma TPM concentrations are linearly related to dosage both in adults and in children and that children aged <10 years require much greater body weight-adjusted dosage to achieve drug levels comparable to those observed in young adults. The marked increase in TPM clearance caused by enzyme-inducing co-medication was confirmed.
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31
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Abstract
Organogenesis throughout childhood affects almost every aspect of pediatric pharmacotherapy. The antiepileptic drugs (AEDs) are particularly impacted since most elimination rates are diminished for the first 6 months of infancy, but quickly attain and supersede adult values. When children enter a hypermetabolic stage, large doses of AEDs may be necessary to maintain effective serum concentrations. Medication noncompliance is frequently confused as hypermetabolism, since both present with low serum drug concentrations. Amazingly, noncompliance among children with chronic illness approaches a similar incidence to that reported in the adult population. It is obviously important to include this in the differential diagnosis of the etiology of subtherapeutic serum AED concentrations. Maturational differences also affect gastrointestinal drug absorption. Intestinal transit time and absorptive surface area are both diminished in young children. Drug delivery systems suitable in adults may not deliver the total dosage in children. Differences in the composition of body compartments and protein binding can alter the volume of drug distribution and, consequently, serum concentrations. In addition to pathophysiologic changes, there is evidence to suggest differences between a mature and immature brain. These differences include quantitative and qualitative responses to neurotransmitters. Hence, it is understandable why seizure semiology is different in children compared with adults. This constellation of factors contributes to the challenges of caring for children with epilepsy.
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Affiliation(s)
- Jamie T Gilman
- Neuroscience Clinical Affairs, Ortho-McNeil Pharmaceuticals Inc, Woodbury, Tennessee, USA.
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32
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Abstract
Pharmacokinetic differences may play a part in the age-related differences in the incidence of adverse effects. The most common idiosyncratic reaction to lamotrigine (LTG) is rash, affecting 10-20% of patients. Risk factors are young age, concurrent valproate (VPA), high starting dose, and rapid escalation. In children, cytochrome P450 (CYP)-catalyzed metabolism is increased, and uridine diphosphate (UDP)-glucuronosyltransferase (UGT)-catalyzed metabolism is not significantly different from that in adults. A CYP-catalyzed arene oxide intermediate of LTG has been identified. The increase CYP metabolism of LTG in children could result in increased formation of the reactive metabolite and a higher incident of rash. Children often received higher milligram per kilogram doses compared with adults. The higher dose would cause an increased amount of LTG metabolized to the reactive arene oxide intermediate. VPA therapy is associated with a transient elevation in liver-function tests in 15-30% of patients and a rare, fatal hepatotoxicity. Most cases of VPA hepatotoxicity occurred in children younger than 2 years who had preexisting neurologic or other physical defects. Hypotheses regarding the pathogenesis of the hepatotoxicity include preexisting mitochondrial disease or inborn errors of metabolism, VPA inhibition of beta-oxidation, and toxicity from VPA metabolites VPA, 4-ene-VPA, and 2,4-diene-VPA. Infants and children have higher concentration ratios of 4-ene-VPA to VPA. Polytherapy with enzyme inducers increases the formation of the hepatotoxic metabolites. The role of underlying metabolic disorders associated with hepatodegeneration and intractable seizures without VPA is a major confounder in identifying risk factors and demonstrates the difficulty in separating underlying disease factors in rare idiosyncratic reactions.
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Affiliation(s)
- Gail D Anderson
- Department of Pharmacy, University of Washington, Seattle 98195, USA.
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Dorne JL, Walton K, Renwick AG. Human variability in glucuronidation in relation to uncertainty factors for risk assessment. Food Chem Toxicol 2001; 39:1153-73. [PMID: 11696390 DOI: 10.1016/s0278-6915(01)00087-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The appropriateness of the default uncertainty factor for human variability in kinetics has been investigated for glucuronidation using an extensive database of substrates metabolised primarily by this pathway. Inter-individual variability was quantified for 15 compounds from published pharmacokinetic studies (after oral and intravenous dosing) in healthy adults and other subgroups using parameters relating to chronic exposure (metabolic and total clearances, area under the plasma concentration time-curve (AUC)) and acute exposure (C(max)). Low inter-individual variability (about 30-35%) was found for all parameters (clearance corrected or not corrected for body weight, metabolic clearance, oral AUC and C(max)) after either iv or oral administration to healthy adults. The overall variability of 31% for glucuronidation in healthy adults supported the validity of the default kinetic uncertainty factor of 3.16 for this group, because it would cover more than 99% of individuals. Comparisons between potentially sensitive subgroups and healthy adults using differences in means and variability indicated that neonates showed the greatest impairment of glucuronidation, and that the 3.16 kinetic default factor applied to the mean data for adults would be inadequate for this subpopulation. The in vivo data have been used to derive pathway-related default factors for compounds eliminated largely via glucuronidation.
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Affiliation(s)
- J L Dorne
- Clinical Pharmacology Group, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, SO16 7PX, Southampton, UK
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Franz DN, Tudor C, Leonard J, Egelhoff JC, Byars A, Valerius K, Sethuraman G. Lamotrigine therapy of epilepsy in tuberous sclerosis. Epilepsia 2001; 42:935-40. [PMID: 11488895 DOI: 10.1046/j.1528-1157.2001.042007935.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE Lamotrigine (LTG), a newer antiepileptic drug (AED), has activity against both partial-onset and generalized seizures. Its reported benefits for behavior, and its effectiveness in Lennox-Gastaut syndrome and other forms of refractory epilepsy, make it a logical choice for treatment of epilepsy in tuberous sclerosis complex (TSC). We present our experience with LTG therapy of epilepsy in 57 patients with TSC. METHODS Patients fulfilled the diagnostic criteria for clinically definite TSC. LTG was initiated and increased until improvement in seizure frequency was noted, intolerable side effects occurred, or maximal doses were reached. Seizure frequency and behavioral changes were recorded during LTG therapy and compared with those prior to the introduction of LTG. RESULTS Twenty-four (42%) were seizure free, and 21 (37%) had a >50% reduction in seizure frequency. Eighteen (32%) had subjectively improved behavior and/or alertness with daily activities. Thirty-eight (67%) had no change in this regard, whereas one (2%) became worse. Responders were more likely to not have a history of infantile spasms, and to have experienced only partial seizures (p < 0.05). Otherwise no phenotypic correlations with response were apparent. CONCLUSIONS Among patients with TSC and epilepsy, LTG was effective and well tolerated, including as initial monotherapy. Improved alertness and behavior were apparent in many patients. The incidence of side effects is similar to that reported for other pediatric populations with symptomatic partial epilepsy. The usefulness of LTG in TSC may relate to an underlying defect of glutamatergic neurotransmission in partial epilepsy.
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Affiliation(s)
- D N Franz
- Department of Pediatrics, University of Cincinnati College of Medicine, Children's Hospital Medical Center, Cincinnati, Ohio 45229-3039, USA.
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Battino D, Croci D, Granata T, Mamoli D, Messina S, Perucca E. Single-Dose Pharmacokinetics of Lamotrigine in Children: Influence of Age and Antiepileptic Comedication. Ther Drug Monit 2001; 23:217-22. [PMID: 11360028 DOI: 10.1097/00007691-200106000-00006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
To evaluate the influence of pediatric age and antiepileptic comedication on the single-dose pharmacokinetics of lamotrigine, 19 patients with epilepsy (10 comedicated with enzyme inducers and 9 comedicated with valproic acid) aged 8 months to 30 years received a single oral dose of lamotrigine (0.6 to 2.2 mg/kg) after an overnight fast. Blood samples were collected for at least 36 hours and plasma lamotrigine concentrations were determined by high-performance liquid chromatography. Pharmacokinetic parameters were calculated by noncompartmental analysis. Lamotrigine half-life (T1/2) and oral clearance (Cl/F) values were significantly lower and significantly higher, respectively, in patients comedicated with enzyme inducers than in those receiving valproic acid (T1/2 = 8.1 vs. 41.7 hours respectively, P < 0.001; Cl/F = 0.11 vs. 0.04 L/h per kg respectively, P < 0.005, geometric means), whereas Cmax and Tmax values were comparable in the two groups. The differences in pharmacokinetic parameters persisted when comparisons were made within subgroups stratified according to age. Within groups of patients homogeneous for type of comedication, Cmax and AUC values tended to be lower in children aged less than 12 years than in older patients. There was no significant relationship between half-life values and age. The authors conclude that both age and type of comedication influence lamotrigine pharmacokinetics. The reduction in lamotrigine concentrations caused by enzyme inducers and the elevation caused by valproic acid can be explained by stimulation and inhibition, respectively, of lamotrigine glucuronidation. On the other hand, the lower plasma lamotrigine levels in children than in adolescents and older patients may not be explainable solely by differences in metabolic rate.
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Affiliation(s)
- D Battino
- Carlo Besta Neurological Institute, Milan; and Clinical Pharmacology Unit, University of Pavia, Pavia, Italy
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Bialer M, Johannessen SI, Kupferberg HJ, Levy RH, Loiseau P, Perucca E. Progress report on new antiepileptic drugs: a summary of the Fifth Eilat Conference (EILAT V). Epilepsy Res 2001; 43:11-58. [PMID: 11137386 DOI: 10.1016/s0920-1211(00)00171-6] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The Fifth Eilat Conference on New Antiepileptic Drugs (AEDs) took place at the Dan Hotel, Eilat, Israel, 25-29 June 2000. Basic scientists, clinical pharmacologists and neurologists from 20 countries attended the conference, whose main themes included recognition of unexpected adverse effects, new indications of AEDs, and patient-tailored AED therapy. According to tradition, the central part of the conference was devoted to a review of AEDs in development, as well to updates on AEDs that have been marketed in recent years. This article summarizes the information presented on drugs in preclinical and clinical development, including AWD 131-138, DP-valproate, harkoseride, LY300164, NPS 1776, NW 1015, pregabalin, remacemide, retigabine, rufinamide and valrocemide. The potential value of an innovative strategy, porcine embryonic GABAergic cell transplants, is also discussed. Finally, updates on felbamate, fosphenytoin, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin, zonisamide, and the antiepileptic vagal stimulator device are presented.
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Affiliation(s)
- M Bialer
- School of Pharmacy and David R. Bloom Centre for Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, 91120, Jerusalem, Israel.
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Gidal BE, Anderson GD, Rutecki PR, Shaw R, Lanning A. Lack of an effect of valproate concentration on lamotrigine pharmacokinetics in developmentally disabled patients with epilepsy. Epilepsy Res 2000; 42:23-31. [PMID: 10996503 DOI: 10.1016/s0920-1211(00)00160-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PURPOSE to describe the population pharmacokinetics of lamotrigine (LTG) in developmentally disabled (DD) patients with epilepsy and (2) to determine if there is an effect of valproate (VPA) concentration on the extent of the pharmacokinetic interaction between VPA and LTG. METHOD a NONMEM population analysis of steady-state LTG serum concentrations was conducted in patients receiving LTG either as mono or polytherapy with either an enzyme inducer (IND)-carbamazepine (CBZ), phenytoin (PHT), phenobarbital (PB) or an inhibitor (VPA). RESULTS sixty-two patients (33.6+/-11.3 years, 47+/-9.9 kg) receiving LTG monotherapy (n=19) or polytherapy with VPA (n=15), inducer(s) (n=32) or both (n=5) were evaluated. LTG dose of 369+/-236 mg per day (8.1+/-5.9 mg/kg per day) achieved LTG plasma concentrations of 6.8+/-3.3 microg/ml. The observed LTG monotherapy, LTG+IND, and LTG+VPA oral clearance (Cl/F) were 0. 69+/-0.2, 1.60+/-0.65 and 0.2+/-0.05 ml/kg per min, respectively. The final LTG Cl/F model was dependent on body weight, concomitant VPA, and either single or multiple inducers. Including the serum concentrations of CBZ, PHT, or VPA in the model, did not significantly improve estimates of Cl/F. CONCLUSION LTG Cl/F in DD patients is similar to literature values for ambulatory adult patients; however, low weight adult patients have higher elimination rates, as well as an increased response to enzyme induction. VPA inhibition of LTG Cl/F is maximal within the usually accepted therapeutic range for VPA.
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Affiliation(s)
- B E Gidal
- Department of Neurology, School of Pharmacy, University of Wisconsin, Madison, WI, USA
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Abstract
Until 1993, carbamazepine (CBZ), phenytoin (PHT), phenobarbital (PB), and valproate (VPA) accounted for the great majority of the prescriptions written for the treatment of epilepsy. Since 1993, five antiepileptic drugs (AEDs) have been released in the United States, and at least three additional drugs are expected to be released by the end of the year 2000. As a group, these newer drugs differ from the established drugs in terms of their pharmacokinetics, interaction potential, and adverse effects. In addition, any one of the newer drugs may achieve seizure control in situations in which an established drug had not. The newer drugs certainly represent a welcome addition to the existing options for the treatment of epilepsy in children. However, the availability of several new AEDs represents a therapeutic dilemma for the clinician because optimal use of these drugs has not yet been established. This is particularly true in children because (i) newer drugs are often studied less frequently in children, (ii) pharmacokinetics in children differ from those in adults, (iii) children may have different adverse effects, and (iv) children have a broader spectrum of various seizure types and epilepsy syndromes. In the first part of this review, the clinical pharmacology of the currently available newer AEDs is discussed individually, with special emphasis on data in children. In particular, pharmacokinetics, interactions, dosage and titration, efficacy spectrum, and adverse effect profile is discussed for each drug. In the second part, an attempt is made to determine the place for the newer drugs in the treatment of the different pediatric seizures and epilepsy syndromes.
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Affiliation(s)
- B F Bourgeois
- Department of Neurology, Harvard Medical School, Boston, Massachusetts, USA
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