1
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Li Y, Allegaert K. Why population pharmacokinetic studies are instrumental to boost clinical research in neonates, and suggestions on how clinicians should assess these papers. Pediatr Res 2024; 95:1181-1183. [PMID: 38195936 DOI: 10.1038/s41390-023-03011-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 12/15/2023] [Indexed: 01/11/2024]
Affiliation(s)
- Yan Li
- GCP office, Children's Hospital Affiliated to Zhengzhou University, 450018, Zhengzhou, China
- Department of Pharmacy, Children's Hospital Affiliated to Zhengzhou University, 450018, Zhengzhou, China
| | - Karel Allegaert
- Department of Development and Regeneration, KU Leuven, Leuven, Belgium.
- Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
- Department of Hospital Pharmacy, Erasmus Medical Center, Rotterdam, The Netherlands.
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2
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Allegaert K. Integrated in a systems pharmacology approach, pharmacogenetics holds the promise for personalized medicine in neonates. Pharmacogenomics 2022; 23:667-670. [PMID: 35929406 DOI: 10.2217/pgs-2022-0100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Tweetable abstract Integrated in a systems pharmacology approach, pharmacogenetics holds the promise for personalized medicine in neonates. This has been illustrated for some diseases specific to neonates.
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Affiliation(s)
- Karel Allegaert
- Department of Pharmaceutical & Pharmacological Sciences, KU Leuven, Leuven, Belgium.,Department of Development & Regeneration, KU Leuven, Leuven, Belgium.,Leuven Child & Youth Institute, KU Leuven, Leuven, Belgium.,Department of Hospital Pharmacy, Erasmus MC, Rotterdam, the Netherlands
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3
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Emoto C, Johnson TN. Cytochrome P450 enzymes in the pediatric population: Connecting knowledge on P450 expression with pediatric pharmacokinetics. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2022; 95:365-391. [PMID: 35953161 DOI: 10.1016/bs.apha.2022.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Cytochrome P450 enzymes play an important role in the pharmacokinetics, efficacy, and toxicity of drugs. Age-dependent changes in P450 enzyme expression have been studied based on several detection systems, as well as by deconvolution of in vivo pharmacokinetic data observed in pediatric populations. The age-dependent changes in P450 enzyme expression can be important determinants of drug disposition in childhood, in addition to the changes in body size and the other physiological parameters, and effects of pharmacogenetics and disease on organ functions. As a tool incorporating drug-specific and body-specific factors, physiologically-based pharmacokinetic (PBPK) models have become increasingly used to characterize and explore mechanistic insights into drug disposition. Thus, PBPK models can be a bridge between findings from basic science and utilization in predictive science. Pediatric PBPK models incorporate additional system specific information on developmental physiology and ontogeny and have been used to predict pharmacokinetic parameters from preterm neonates onwards. These models have been advocated by regulatory authorities in order to support pediatric clinical trials. The purpose of this chapter is to highlight accumulated knowledge and findings from basic research focusing on P450 enzymes, as well as the current status and future challenges of expanding the utilization of pediatric PBPK modeling.
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Affiliation(s)
- Chie Emoto
- Laboratory of Drug Metabolism and Pharmacokinetics, Showa Pharmaceutical University, Tokyo, Japan; Translational Research Division, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan.
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Mørk ML, Andersen JT, Lausten-Thomsen U, Gade C. The Blind Spot of Pharmacology: A Scoping Review of Drug Metabolism in Prematurely Born Children. Front Pharmacol 2022; 13:828010. [PMID: 35242037 PMCID: PMC8886150 DOI: 10.3389/fphar.2022.828010] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 01/25/2022] [Indexed: 12/30/2022] Open
Abstract
The limit for possible survival after extremely preterm birth has steadily improved and consequently, more premature neonates with increasingly lower gestational age at birth now require care. This specialized care often include intensive pharmacological treatment, yet there is currently insufficient knowledge of gestational age dependent differences in drug metabolism. This potentially puts the preterm neonates at risk of receiving sub-optimal drug doses with a subsequent increased risk of adverse or insufficient drug effects, and often pediatricians are forced to prescribe medication as off-label or even off-science. In this review, we present some of the particularities of drug disposition and metabolism in preterm neonates. We highlight the challenges in pharmacometrics studies on hepatic drug metabolism in preterm and particularly extremely (less than 28 weeks of gestation) preterm neonates by conducting a scoping review of published literature. We find that >40% of included studies failed to report a clear distinction between term and preterm children in the presentation of results making direct interpretation for preterm neonates difficult. We present summarized findings of pharmacokinetic studies done on the major CYP sub-systems, but formal meta analyses were not possible due the overall heterogeneous approaches to measuring the phase I and II pathways metabolism in preterm neonates, often with use of opportunistic sampling. We find this to be a testament to the practical and ethical challenges in measuring pharmacokinetic activity in preterm neonates. The future calls for optimized designs in pharmacometrics studies, including PK/PD modeling-methods and other sample reducing techniques. Future studies should also preferably be a collaboration between neonatologists and clinical pharmacologists.
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Affiliation(s)
- Mette Louise Mørk
- Department of Clinical Pharmacology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Jón Trærup Andersen
- Department of Clinical Pharmacology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
| | - Ulrik Lausten-Thomsen
- Department of Neonatology, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Christina Gade
- Department of Clinical Pharmacology, Copenhagen University Hospital Bispebjerg and Frederiksberg, Copenhagen, Denmark
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5
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Long T, Cristofoletti R, Cicali B, Michaud V, Dow P, Turgeon J, Schmidt S. Physiologically-based Pharmacokinetic Modeling to Assess the Impact of CYP2D6-Mediated Drug-Drug Interactions on Tramadol and O-Desmethyltramadol Exposures via Allosteric and Competitive Inhibition. J Clin Pharmacol 2021; 62:76-86. [PMID: 34383318 PMCID: PMC9293201 DOI: 10.1002/jcph.1951] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 08/06/2021] [Indexed: 11/11/2022]
Abstract
Tramadol is an opioid medication used to treat moderately severe pain. Cytochrome P450 (CYP) 2D6 inhibition could be important for tramadol, as it decreases the formation of its pharmacologically active metabolite, O‐desmethyltramadol, potentially resulting in increased opioid use and misuse. The objective of this study was to evaluate the impact of allosteric and competitive CYP2D6 inhibition on tramadol and O‐desmethyltramadol pharmacokinetics using quinidine and metoprolol as prototypical perpetrator drugs. A physiologically based pharmacokinetic model for tramadol and O‐desmethyltramadol was developed and verified in PK‐Sim version 8 and linked to respective models of quinidine and metoprolol to evaluate the impact of allosteric and competitive CYP2D6 inhibition on tramadol and O‐desmethyltramadol exposure. Our results show that there is a differentiated impact of CYP2D6 inhibitors on tramadol and O‐desmethyltramadol based on their mechanisms of inhibition. Following allosteric inhibition by a single dose of quinidine, the exposure of both tramadol (51% increase) and O‐desmethyltramadol (52% decrease) was predicted to be significantly altered after concomitant administration of a single dose of tramadol. Following multiple‐dose administration of tramadol and a single‐dose or multiple‐dose administration of quinidine, the inhibitory effect of quinidine was predicted to be long (≈42 hours) and to alter exposure of tramadol and O‐desmethyltramadol by up to 60%, suggesting that coadministration of quinidine and tramadol should be avoided clinically. In comparison, there is no predicted significant impact of metoprolol on tramadol and O‐desmethyltramadol exposure. In fact, tramadol is predicted to act as a CYP2D6 perpetrator and increase metoprolol exposure, which may necessitate the need for dose separation.
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Affiliation(s)
- Tao Long
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, FL, USA
| | - Rodrigo Cristofoletti
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, FL, USA
| | - Brian Cicali
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, FL, USA
| | - Veronique Michaud
- Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Orlando, FL, USA.,Faculty of Pharmacy, Université de Montréal, Montréal, Quebec, Canada
| | - Pamela Dow
- Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Orlando, FL, USA
| | - Jacques Turgeon
- Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Orlando, FL, USA.,Faculty of Pharmacy, Université de Montréal, Montréal, Quebec, Canada
| | - Stephan Schmidt
- Center for Pharmacometrics and Systems Pharmacology, Department of Pharmaceutics, College of Pharmacy, University of Florida, Orlando, FL, USA
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Anderson BJ, Morse JD, Hannam JA, Cortinez LI. Pharmacokinetic and pharmacodynamic considerations of general anesthesia in pediatric subjects. Expert Opin Drug Metab Toxicol 2020; 16:279-295. [PMID: 32148110 DOI: 10.1080/17425255.2020.1739648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Introduction: The target concentration strategy uses PKPD information for dose determination. Models have also quantified exposure-response relationships, improved understanding of developmental pharmacokinetics, rationalized dose prescription, provided insight into the importance of covariate information, explained drug interactions and driven decision-making and learning during drug development.Areas covered: The prime PKPD consideration is parameter estimation and quantification of variability. The main sources of variability in children are age (maturation) and weight (size). Model use is mostly confined to pharmacokinetics, partly because anesthesia effect models in the young are imprecise. Exploration of PK and PD covariates and their variability hold potential to better individualize treatment.Expert opinion: The ability to model drugs using computer-based technology is hindered because covariate data required to individualize treatment using these programs remain lacking. Target concentration intervention strategies remain incomplete because covariate information that might better predict individualization of dose is absent. Pharmacogenomics appear a valuable area for investigation for pharmacodynamics and pharmacodynamics. Effect measures in the very young are imprecise. Assessment of the analgesic component of anesthesia is crude. While neuromuscular monitoring is satisfactory, depth of anaesthesia EEG interpretation is inadequate. Closed loop anesthesia is possible with better understanding of EEG changes.
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Affiliation(s)
- Brian J Anderson
- Department of Anaesthesiology, University of Auckland, Auckland, New Zealand
| | - James D Morse
- Department of Pharmacology & Clinical Pharmacology, University of Auckland, Auckland, New Zealand
| | - Jacqueline A Hannam
- Department of Pharmacology & Clinical Pharmacology, University of Auckland, Auckland, New Zealand
| | - L Ignacio Cortinez
- División Anestesiología, Pontificia Universidad Católica De Chile, Santiago De Chile, Chile
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Palmer GM, Anderson BJ, Linscott DK, Paech MJ, Allegaert K. Tramadol, breast feeding and safety in the newborn. Arch Dis Child 2018; 103:1110-1113. [PMID: 29599166 DOI: 10.1136/archdischild-2017-313786] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 02/26/2018] [Accepted: 02/27/2018] [Indexed: 11/04/2022]
Affiliation(s)
- Greta M Palmer
- Department of Paediatric Anaesthesia and Pain Management, Royal Children's Hospital; University of Melbourne and Murdoch Children's Research Institute, Parkville, Victoria, Australia
| | - Brian J Anderson
- Department of Anaesthesiology, Faculty of Medicine and Health Science, University of Auckland, Auckland, New Zealand
| | - David K Linscott
- Department of Anaesthesia, Christchurch Hospital; University of Otago, Christchurch, New Zealand
| | - Michael J Paech
- The University of Western Australia, Perth, Western Australia, Australia.,Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital, Perth, Western Australia, Australia
| | - Karel Allegaert
- Intensive Care and Department of Pediatric Surgery and Neonatology, Erasmus MC Sophia Children's Hospital, Rotterdam, The Netherlands.,Department of Development and Regeneration, KU Leuven, Leuven, Belgium
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8
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T'jollyn H, Vermeulen A, Van Bocxlaer J. PBPK and its Virtual Populations: the Impact of Physiology on Pediatric Pharmacokinetic Predictions of Tramadol. AAPS JOURNAL 2018; 21:8. [PMID: 30498862 DOI: 10.1208/s12248-018-0277-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 11/09/2018] [Indexed: 11/30/2022]
Abstract
In pediatric PBPK models, age-related changes in the body are known to occur. Given the sparsity of and the variability associated with relevant physiological parameters, different PBPK software providers may vary in their system's data. In this work, three commercially available PBPK software packages (PK-Sim®, Simcyp®, and Gastroplus®) were investigated regarding their differences in system-related information, possibly affecting clearance prediction. Three retrograde PBPK clearance models were set up to enable prediction of pediatric tramadol clearance. These models were qualified in terms of total, CYP2D6, and renal clearance in adults. Tramadol pediatric clearance predictions from PBPK were compared with a pooled popPK model covering clearance ranging from neonates to adults. Fold prediction errors were used to evaluate the results. Marked differences in liver clearance prediction between PBPK models were observed. In general, the prediction bias of total clearance was greatest at the youngest population and decreased with age. Regarding CYP2D6 and renal clearance, important differences exist between PBPK software tools. Interestingly, the PBPK model with the shortest CYP2D6 maturation half-life (PK-Sim) agreed best with the in vivo CYP2D6 maturation model. Marked differences in physiological data explain the observed differences in hepatic clearance prediction in early life between the various PBPK software providers tested. Consensus on the most suited pediatric data to use should harmonize and optimize pediatric clearance predictions. Moreover, the combination of bottom-up and top-down approaches, using a convenient probe substrate, has the potential to update system-related parameters in order to better represent pediatric physiology.
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Affiliation(s)
- Huybrecht T'jollyn
- A Division of Janssen Pharmaceutica NV, Quantitative Sciences, Janssen Research and Development, Beerse, Belgium.
| | - An Vermeulen
- A Division of Janssen Pharmaceutica NV, Quantitative Sciences, Janssen Research and Development, Beerse, Belgium.,Faculty of Pharmaceutical Sciences, Laboratory of Medical Biochemistry and Clinical Analysis, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Jan Van Bocxlaer
- Faculty of Pharmaceutical Sciences, Laboratory of Medical Biochemistry and Clinical Analysis, Ottergemsesteenweg 460, 9000, Ghent, Belgium
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Zeilmaker GA, Pokorna P, Mian P, Wildschut ED, Knibbe CAJ, Krekels EHJ, Allegaert K, Tibboel D. Pharmacokinetic considerations for pediatric patients receiving analgesia in the intensive care unit; targeting postoperative, ECMO and hypothermia patients. Expert Opin Drug Metab Toxicol 2018; 14:417-428. [PMID: 29623729 DOI: 10.1080/17425255.2018.1461836] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Adequate postoperative analgesia in pediatric patients in the intensive care unit (ICU) matters, since untreated pain is associated with negative outcomes. Compared to routine postoperative patients, children undergoing hypothermia (HT) or extracorporeal membrane oxygenation (ECMO), or recovering after cardiac surgery likely display non-maturational differences in pharmacokinetics (PK) and pharmacodynamics (PD). These differences warrant additional dosing recommendations to optimize pain treatment. Areas covered: Specific populations within the ICU will be discussed with respect to expected variations in PK and PD for various analgesics. We hereby move beyond maturational changes and focus on why PK/PD may be different in children undergoing HT, ECMO or cardiac surgery. We provide a stepwise manner to develop PK-based dosing regimens using population PK approaches in these populations. Expert opinion: A one-dose to size-fits-all for analgesia is suboptimal, but for several commonly used analgesics the impact of HT, ECMO or cardiac surgery on average PK parameters in children is not yet sufficiently known. Parameters considering both maturational and non-maturational covariates are important to develop population PK-based dosing advices as part of a strategy to optimize pain treatment.
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Affiliation(s)
- Gerdien A Zeilmaker
- a Intensive Care and Department of Pediatric Surgery , Erasmus MC-Sophia Children's Hospital , Rotterdam , The Netherlands
| | - Paula Pokorna
- a Intensive Care and Department of Pediatric Surgery , Erasmus MC-Sophia Children's Hospital , Rotterdam , The Netherlands.,b Department of Pediatrics, General Faculty Hospital Prague, First Faculty of Medicine , Charles University and General University Hospital in Prague , Prague , Czech Republic.,c Institute of Pharmacology, First Faculty of Medicine , Charles University and General University Hospital in Prague , Prague , Czech Republic
| | - Paola Mian
- a Intensive Care and Department of Pediatric Surgery , Erasmus MC-Sophia Children's Hospital , Rotterdam , The Netherlands
| | - Enno D Wildschut
- a Intensive Care and Department of Pediatric Surgery , Erasmus MC-Sophia Children's Hospital , Rotterdam , The Netherlands
| | - Catherijne A J Knibbe
- d Division of Pharmacology , LACDR, Leiden University , Leiden , The Netherlands.,e Department of Clinical Pharmacy , St. Antonius Hospital , Nieuwegein , The Netherlands
| | - Elke H J Krekels
- d Division of Pharmacology , LACDR, Leiden University , Leiden , The Netherlands
| | - Karel Allegaert
- a Intensive Care and Department of Pediatric Surgery , Erasmus MC-Sophia Children's Hospital , Rotterdam , The Netherlands.,f Department of Development and Regeneration , KU Leuven , Leuven , Belgium
| | - Dick Tibboel
- a Intensive Care and Department of Pediatric Surgery , Erasmus MC-Sophia Children's Hospital , Rotterdam , The Netherlands
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Affiliation(s)
- Brian J Anderson
- Department of Anaesthesiology, Faculty of Medicine and Health Science, University of Auckland, Auckland, New Zealand
| | - Jane Thomas
- Department of Anaesthesia, Starship Children's Hospital, Auckland, New Zealand
| | - Kaye Ottaway
- Department of Anaesthesiology, Faculty of Medicine and Health Science, University of Auckland, Auckland, New Zealand
| | - George A Chalkiadis
- Department of Paediatric Anaesthesia and Pain Management, Royal Children's Hospital, Parkville, Vic, Australia
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11
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Allegaert K, Holford N, Anderson BJ, Holford S, Stuber F, Rochette A, Trocóniz IF, Beier H, de Hoon JN, Pedersen RS, Stamer U. Tramadol and o-desmethyl tramadol clearance maturation and disposition in humans: a pooled pharmacokinetic study. Clin Pharmacokinet 2015; 54:167-78. [PMID: 25258277 DOI: 10.1007/s40262-014-0191-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND OBJECTIVES We aimed to study the impact of size, maturation and cytochrome P450 2D6 (CYP2D6) genotype activity score as predictors of intravenous tramadol disposition. METHODS Tramadol and O-desmethyl tramadol (M1) observations in 295 human subjects (postmenstrual age 25 weeks to 84.8 years, weight 0.5-186 kg) were pooled. A population pharmacokinetic analysis was performed using a two-compartment model for tramadol and two additional M1 compartments. Covariate analysis included weight, age, sex, disease characteristics (healthy subject or patient) and CYP2D6 genotype activity. A sigmoid maturation model was used to describe age-related changes in tramadol clearance (CLPO), M1 formation clearance (CLPM) and M1 elimination clearance (CLMO). A phenotype-based mixture model was used to identify CLPM polymorphism. RESULTS Differences in clearances were largely accounted for by maturation and size. The time to reach 50 % of adult clearance (TM50) values was used to describe maturation. CLPM (TM50 39.8 weeks) and CLPO (TM50 39.1 weeks) displayed fast maturation, while CLMO matured slower, similar to glomerular filtration rate (TM50 47 weeks). The phenotype-based mixture model identified a slow and a faster metabolizer group. Slow metabolizers comprised 9.8 % of subjects with 19.4 % of faster metabolizer CLPM. Low CYP2D6 genotype activity was associated with lower (25 %) than faster metabolizer CLPM, but only 32 % of those with low genotype activity were in the slow metabolizer group. CONCLUSIONS Maturation and size are key predictors of variability. A two-group polymorphism was identified based on phenotypic M1 formation clearance. Maturation of tramadol elimination occurs early (50 % of adult value at term gestation).
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Affiliation(s)
- Karel Allegaert
- Neonatal Intensive Care Unit and Center for Clinical Pharmacology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium,
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12
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T'jollyn H, Snoeys J, Vermeulen A, Michelet R, Cuyckens F, Mannens G, Van Peer A, Annaert P, Allegaert K, Van Bocxlaer J, Boussery K. Physiologically Based Pharmacokinetic Predictions of Tramadol Exposure Throughout Pediatric Life: an Analysis of the Different Clearance Contributors with Emphasis on CYP2D6 Maturation. AAPS JOURNAL 2015. [PMID: 26209290 DOI: 10.1208/s12248-015-9803-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This paper focuses on the retrospective evaluation of physiologically based pharmacokinetic (PBPK) techniques used to mechanistically predict clearance throughout pediatric life. An intravenous tramadol retrograde PBPK model was set up in Simcyp® using adult clearance values, qualified for CYP2D6, CYP3A4, CYP2B6, and renal contributions. Subsequently, the model was evaluated for mechanistic prediction of total, CYP2D6-related, and renal clearance predictions in very early life. In two in vitro pediatric human liver microsomal (HLM) batches (1 and 3 months), O-desmethyltramadol and N-desmethyltramadol formation rates were compared with CYP2D6 and CYP3A4 activity, respectively. O-desmethyltramadol formation was mediated only by CYP2D6, while N-desmethyltramadol was mediated in part by CYP3A4. Additionally, the clearance maturation of the PBPK model predictions was compared to two in vivo maturation models (Hill and exponential) based on plasma concentration data, and to clearance estimations from a WinNonlin® fit of plasma concentration and urinary excretion data. Maturation of renal and CYP2D6 clearance is captured well in the PBPK model predictions, but total tramadol clearance is underpredicted. The most pronounced underprediction of total and CYP2D6-mediated clearance was observed in the age range of 2-13 years. In conclusion, the PBPK technique showed to be a powerful mechanistic tool capable of predicting maturation of CYP2D6 and renal tramadol clearance in early infancy, although some underprediction occurs between 2 and 13 years for total and CYP2D6-mediated tramadol clearance.
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Affiliation(s)
- Huybrecht T'jollyn
- Laboratory of Medical Biochemistry and Clinical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, B-9000, Ghent, Belgium.
| | - Jan Snoeys
- Janssen Research & Development, Division of Janssen Pharmaceutica NV, Turnhoutseweg 30, B-2340, Beerse, Belgium
| | - An Vermeulen
- Laboratory of Medical Biochemistry and Clinical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, B-9000, Ghent, Belgium
| | - Robin Michelet
- Laboratory of Medical Biochemistry and Clinical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, B-9000, Ghent, Belgium
| | - Filip Cuyckens
- Janssen Research & Development, Division of Janssen Pharmaceutica NV, Turnhoutseweg 30, B-2340, Beerse, Belgium
| | - Geert Mannens
- Janssen Research & Development, Division of Janssen Pharmaceutica NV, Turnhoutseweg 30, B-2340, Beerse, Belgium
| | - Achiel Van Peer
- Janssen Research & Development, Division of Janssen Pharmaceutica NV, Turnhoutseweg 30, B-2340, Beerse, Belgium
| | - Pieter Annaert
- Drug Delivery & Disposition, KU Leuven Department of Pharmaceutical and Pharmacological Sciences, O&N2, Herestraat, 49-box 921, B-3000, Leuven, Belgium
| | - Karel Allegaert
- Department of Development and Regeneration, KU Leuven and Neonatal Intensive Care Unit, University Hospitals Leuven, B-3000, Leuven, Belgium
| | - Jan Van Bocxlaer
- Laboratory of Medical Biochemistry and Clinical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, B-9000, Ghent, Belgium
| | - Koen Boussery
- Laboratory of Medical Biochemistry and Clinical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, B-9000, Ghent, Belgium
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Allegaert K, van den Anker J. Neonatal drug therapy: The first frontier of therapeutics for children. Clin Pharmacol Ther 2015; 98:288-97. [PMID: 26095519 DOI: 10.1002/cpt.166] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 06/08/2015] [Indexed: 02/06/2023]
Abstract
Knowledge about the safe and effective use of medicines in neonates has increased substantially but has resulted in few label changes. Drugs developed for use in adults are reshaped and tailored to specific neonatal indications. However, the use of drugs in neonates should not only mirror adult pharmacotherapy, but should be driven by their own specific needs. Therefore, building collaborative networks may assist to develop a newborn-driven research agenda addressing their clinical needs and diseases.
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Affiliation(s)
- K Allegaert
- Neonatal Intensive Care Unit, University Hospitals Leuven, Leuven, Belgium
- Department of Development and Regeneration, KU, Leuven, Belgium
| | - J van den Anker
- Division of Pediatric Clinical Pharmacology, Children's National Health System, Washington, DC, USA
- Departments of Pediatrics, Integrative Systems Biology, Pharmacology and Physiology, George Washington University School of Medicine and Health Sciences, Washington, DC, USA
- Intensive Care and Department of Pediatric Surgery, Erasmus MC - Sophia Children's Hospital, Rotterdam, the Netherlands
- Department of Paediatric Pharmacology, University Children's Hospital Basel, Basel, Switzerland
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Olischar M, Palmer GM, Orsini F, Davidson AJ, Perkins EJ, Lee KJ, Everest NJ, Cranswick NE, Hunt RW. The addition of tramadol to the standard of i.v. acetaminophen and morphine infusion for postoperative analgesia in neonates offers no clinical benefit: a randomized placebo-controlled trial. Paediatr Anaesth 2014; 24:1149-57. [PMID: 25040756 DOI: 10.1111/pan.12477] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/04/2014] [Indexed: 11/30/2022]
Abstract
BACKGROUND Tramadol is used following neonatal cardiac and general surgery. However, its ability to opioid-spare or facilitate earlier extubation in postoperative neonates is unquantified. OBJECTIVE This randomized placebo-controlled trial aimed to assess whether tramadol's addition to standard analgesia resulted in earlier extubation or reduced analgesic/sedative requirements in postsurgical neonates. METHODS Neonates born ≥32 weeks postmenstrual age received either tramadol [T] 2 mg·kg(-1) or placebo [P] 6-hourly for up to 5 days postthoracoabdominal surgery in addition to morphine (commenced at 20 mcg·kg(-1) ·h(-1)) and 6-hourly i.v. acetaminophen. Time to extubation, morphine and midazolam amounts, hourly pain scores, and seizure activity were compared using an intention-to-treat and per-protocol analysis. RESULTS Seventy-one neonates participated. Median survival time to extubation was similar between the groups (T 67 h [95% CI 51, 84] vs P 52 h [95%CI 43, 65]; P = 0.4), and similar numbers were extubated by 96 h (T 69% vs P 77%; difference -8%, 95%CI -28, 13%). Morphine and midazolam exposure was similar, with low pain scores in both groups (mean percentage of time with a pain score >5/20 during the 5 days: T 13% vs P 11%, difference in means 2.8 [95% CI -1.8, 7.6], P = 0.20). Most participants had normal cranial ultrasounds (T 86% vs P 86%); no seizures occurred clinically or electroencephalographically. CONCLUSION Tramadol's addition to standard analgesia in this small group of postsurgical neonates did not appear to have any positive effect on time to extubation, morphine or midazolam exposure, or pain scores. This questions the benefit of tramadol for postsurgical neonates. Importantly, no seizures occurred in these ill neonates who may potentially be at greater risk of tramadol toxicity compared with adults.
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Affiliation(s)
- Monika Olischar
- Department of Neonatal Medicine, The Royal Children's Hospital, Melbourne, VIC., Australia; Department of Neonatology, University Children's Hospital Vienna, Vienna, Austria
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Population pharmacokinetic modelling of tramadol using inverse Gaussian function for the assessment of drug absorption from prolonged and immediate release formulations. Int J Pharm 2014; 473:170-8. [DOI: 10.1016/j.ijpharm.2014.07.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 07/03/2014] [Accepted: 07/05/2014] [Indexed: 11/18/2022]
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Abstract
INTRODUCTION Extensive within-population variability is the essence of neonatal pharmacology. Despite this, infants remain one of the last therapeutic orphans. Together with additional legal initiatives, tailoring of already available tools (modeling, covariates, pharmacovigilance) may significantly improve pharmacotherapy in infants. AREAS COVERED Modeling approaches that hold the promise to improve pharmacotherapy in infants are between-compound extrapolation for compounds that undergo the same route of elimination and integration of time-varying physiology to adapt for the fast maturational changes. Besides these maturational covariates (size, age), newly emerging covariates relate to novel treatment modalities (extracorporeal circulation, hypothermia), environmental issues (microbiome, critical illness) or pharmacogenetics. All these covariates interact with the maturational variation. Finally, pharmacovigilance also needs to be tailored to the characteristics of this population. This relates to preventive strategies, signal detection and assessment of causality. EXPERT OPINION Knowledge on pharmacotherapy in infants is lagging. Tailoring available tools to the specific characteristics (maturation) and clinical needs (newly emerging covariates) of infants is feasible but needs creativity and a multidisciplinary collaboration between modelers, academia, clinical researchers and, obviously, the public, including parents.
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Affiliation(s)
- Karel Allegaert
- University Hospitals Leuven, Neonatal Intensive Care Unit , Herestraat 49, 3000 Leuven , Belgium +32 16 343850 ; +32 16 343209 ;
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Allegaert K, Fanos V, van den Anker JN, Laër S. Perinatal pharmacology. BIOMED RESEARCH INTERNATIONAL 2014; 2014:101620. [PMID: 24822175 PMCID: PMC4005049 DOI: 10.1155/2014/101620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Accepted: 02/19/2014] [Indexed: 02/03/2023]
Affiliation(s)
- Karel Allegaert
- Department of Development and Regeneration, KU Leuven and Neonatal Intensive Care Unit, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Vassilios Fanos
- Department of Surgery, Section of Neonatal Intensive Care Unit, Puericulture Institute and Neonatal Section, University of Cagliari, Cagliari, Italy
| | - Johannes N. van den Anker
- Departments of Pediatrics, Pharmacology, Physiology, and Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, Washington DC, USA
- Intensive Care, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands
- Department of Pediatric Pharmacology, University Children's Hospital Basel, Basel, Switzerland
| | - Stephanie Laër
- Department of Clinical Pharmacy and Pharmacotherapy, Heinrich Heine University of Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
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Abstract
Drug therapy is a powerful tool for improving neonatal outcome. Despite this, neonatologists still routinely prescribe off-label compounds developed for adults and extrapolate doses from those used for children or adults. Knowledge integration through pharmacokinetic modeling is a method that could improve the current situation. Such predictive models may convert neonatal pharmacotherapy from explorative to confirmatory. This can be illustrated by research projects related to the prediction of neonatal renal clearance and neonatal glucuronidation. This type of model will also improve the current knowledge of neonatal (patho)physiology. In the meanwhile, the fields of clinical pharmacology (e.g. pharmacokinetic/pharmacodynamic modeling and pharmacogenetics) and neonatology (e.g. whole-body cooling and the lower limit of viability) have both matured, resulting in new research topics. However, in order for the modeling and the newly emerging topics to become effective tools, they need to be tailored to the specific characteristics of neonates. Consequently, the field of neonatal pharmacotherapy needs dedicated neonatologists who continue to raise the awareness that off-label practices, eminence-based dosing regimens and the absence of neonatal drug formulations all reflect suboptimal care.
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Affiliation(s)
- Karel Allegaert
- Neonatal Intensive Care Unit, University Hospitals Leuven, Leuven, Belgium
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Abstract
Effective and safe drug administration in neonates should be based on integrated knowledge on the evolving physiological characteristics of the infant who will receive the drug and the pharmacokinetics (PK) and pharmacodynamics (PD) of a given drug. Consequently, clinical pharmacology in neonates is as dynamic and diverse as the neonates we admit to our units while covariates explaining the variability are at least as relevant as median estimates. The unique setting of neonatal clinical pharmacology will be highlighted based on the hazards of simple extrapolation of maturational drug clearance when only based on 'adult' metabolism (propofol, paracetamol). Second, maturational trends are not at the same pace for all maturational processes. This will be illustrated based on the differences between hepatic and renal maturation (tramadol, morphine, midazolam). Finally, pharmacogenetics should be tailored to neonates, not just mirror adult concepts. Because of this diversity, clinical research in the field of neonatal clinical pharmacology is urgently needed and facilitated through PK/PD modeling. In addition, irrespective of already available data to guide pharmacotherapy, pharmacovigilance is needed to recognize specific side effects. Consequently, pediatric anesthesiologists should consider to contribute to improved pharmacotherapy through clinical trial design and collaboration, as well as reporting on adverse effects of specific drugs.
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Affiliation(s)
- Karel Allegaert
- Department of Development and Regeneration, KU Leuven, Leuven, University Hospitals Leuven, Belgium,Neonatal Intensive Care Unit, University Hospitals Leuven, Belgium
| | - Marc van de Velde
- Department of Cardiovascular Sciences, KU Leuven, University Hospitals Leuven, Leuven, Belgium,Anesthesiology, University Hospitals Leuven, Leuven, Belgium
| | - John van den Anker
- Division of Pediatric Clinical Pharmacology, Children's National Medical Center, Washington, USA,Departments of Pediatrics, Pharmacology, Physiology and Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, Washington, USA,Intensive Care, Erasmus MC- Sophia Children's Hospital, Rotterdam, the Netherlands
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Allegaert K, Tibboel D, van den Anker J. Pharmacological treatment of neonatal pain: in search of a new equipoise. Semin Fetal Neonatal Med 2013; 18:42-7. [PMID: 23107602 PMCID: PMC4709244 DOI: 10.1016/j.siny.2012.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Inadequate management of pain in early human life contributes to impaired neurodevelopmental outcome and alters pain thresholds, pain or stress-related behavior and physiological responses. However, there are also emerging animal experimental data on the impact of exposure to analgo-sedatives on the incidence and extent of neuro-apoptosis. Since this association has also been suggested in humans, the pharmacological treatment of neonatal pain is in search of a new equipoise since these 'conflicting' observations are the main drivers to further reconsider our current treatment regimens. This review focuses on new data concerning clinical pharmacology of morphine, followed by data on more recently introduced opioids like remifentanil and tramadol, locoregional anesthesia and minimally invasive techniques in neonates, and finally with data on intravenous paracetamol. Since the available data are still incomplete, priorities for both clinical management and future research will be proposed.
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Affiliation(s)
- Karel Allegaert
- Neonatal Intensive Care Unit, University Hospital, Herestraat 49, 3000 Leuven, Belgium.
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Abstract
Anaesthesia dosing in infants (0-2 years) should be based on pharmacokinetic-pharmacodynamic considerations and adverse effects profiles. Disease processes and treatments in this group are distinct from those in adults. Absorption, distribution and clearance change dramatically during this period because of maturation of anatomical and physiological processes as well as behavioural changes. Pharmacogenomic expression also matures in this period. Population-based and physiological-based pharmacokinetic modelling has improved the understanding of maturation and subsequent dose approximation. Postmenstrual, rather than postnatal, age is a reasonable measure for maturation. There remains a need for clinically applicable tools to assess pharmacodynamics which can provide response feedback; this has been achieved for neuromuscular monitoring, but not yet fully for depth of anaesthesia, sedation or pain. Morbidity and mortality associated with paediatric anaesthesia have historically been highest in this age group and continue to be so. Some of this morbidity was attributable to a poor understanding of developmental pharmacology; this facet continues to plague the specialty.
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Abstract
The pharmacokinetic (PK) parameters that are important for dosing (e.g., clearance and volume) are well known. They are used in universal mathematical formulae that describe the time course of drug concentration. Additional formulae can be used to describe major covariate effects in children, such as size and maturation. PK parameters describing the time-concentration profile of a drug after administration are those for a typical individual in a population. These parameters are associated with variability. Further, any one individual may not be typical of the population studied. While size and maturation are two important considerations in children and assist with dosing estimation, there are also a number of additional PK covariates (e.g., organ function, disease, drug interactions, pharmacogenetics), and identifying these sources of variability allows us to individualize drug dose. Pharmacology is not simply an application of PK, and determinants of drug dose also require an understanding of the variability associated with pharmacodynamic response and a balancing of beneficial effects against unwanted effects. Each child is unique in this respect.
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Affiliation(s)
- Brian J Anderson
- Paediatric Intensive Care Unit, Auckland Children's Hospital, Auckland, New Zealand.
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Bloor M, Paech MJ, Kaye R. Tramadol in pregnancy and lactation. Int J Obstet Anesth 2012; 21:163-7. [PMID: 22317891 DOI: 10.1016/j.ijoa.2011.10.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 10/22/2011] [Indexed: 10/14/2022]
Abstract
Tramadol produces analgesic effects through both non-opioid and weak opioid activity and is commonly used to treat mild to moderate pain. It has been in use for over 30 years and has a well-established safety profile in the general population. Since tramadol is not licensed for use in pregnancy and lactation, there is limited clinical research on its use in this patient population. A systematic review was undertaken of articles published in English before June 2011, searching Pubmed, Medline, CINAHL, Embase and Cochrane databases using the terms 'tramadol and pregnancy', 'tramadol and breastfeeding', 'tramadol and lactation', and 'tramadol and neonate'.
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Affiliation(s)
- M Bloor
- Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital for Women, Subiaco, Australia
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Population pharmacokinetic modeling of tramadol and its O-desmethyl metabolite in plasma and breast milk. Eur J Clin Pharmacol 2011; 67:899-908. [DOI: 10.1007/s00228-011-1023-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 02/21/2011] [Indexed: 10/18/2022]
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Individualized dosing regimens in children based on population PKPD modelling: are we ready for it? Int J Pharm 2011; 415:9-14. [PMID: 21376791 DOI: 10.1016/j.ijpharm.2011.02.056] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 02/23/2011] [Accepted: 02/25/2011] [Indexed: 12/20/2022]
Abstract
Despite profound differences in response between children and adults, and between children of different ages, drugs are still empirically dosed in mg/kg in children. Since maturation of expression and function is typically a non-linear dynamic process which differs between biotransformation routes and pharmacological targets, paediatric dosing regimens should be based on the changing pharmacokinetic-pharmacodynamic (PKPD) relationship in children. In this respect, the population approach is essential, allowing for sparse sampling in each individual child. An example is presented on morphine glucuronidation, for which two covariates were identified and subsequently used to derive a model-based dosing algorithm for a prospective clinical trial in children. Using this novel dosing algorithm, similar morphine concentrations are expected while, depending on age, lower and higher morphine dosages are administered compared to mg/kg/h dosing. As the covariate functions may reflect system-specific information on the maturation of a specific drug-disposition pathway, its use for other drugs that share the same pathway is explored. For this purpose, prospective clinical trials and cross-validation studies are urgently needed. In conclusion, PKPD modelling and simulation studies are important to develop evidence-based and individualized dosing schemes for children, with the ultimate goal to improve drug safety and efficacy in this population.
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Allegaert K, Rochette A, Veyckemans F. Developmental pharmacology of tramadol during infancy: ontogeny, pharmacogenetics and elimination clearance. Paediatr Anaesth 2011; 21:266-73. [PMID: 20723094 DOI: 10.1111/j.1460-9592.2010.03389.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIMS AND OBJECTIVES To illustrate the complex interaction between ontogeny, i.e., age-dependent maturation, genetic polymorphisms and renal elimination clearance during infancy, based on developmental disposition of intravenous tramadol during infancy. BACKGROUND Tramadol (M) is metabolized by O-demethylation (cytochrome P450 [CYP] 2D6) to the pharmacodynamic active metabolite O-demethyl tramadol (M1). This metabolite is subsequently eliminated by renal route while M1 formation will in part depend on ontogeny, i.e., age-dependent activity and CYP2D6 polymorphisms. However, these pathways do not mature simultaneously. METHODS A pooled pharmacokinetic analysis of earlier reported time-concentration profiles in neonates and infants was performed with subsequent simulation of the impact of ontogeny, polymorphisms and renal elimination clearance during infancy. RESULTS Tramadol plasma time-concentration profile changes with postmenstrual age. The highest metabolite concentrations occur in the 52-week infant, where M1 formation clearance (hepatic, CYP2D6) is already mature but metabolite elimination clearance (through glomerular filtration rate) is immature. DISCUSSION The phenotypic observations might in part explain unanticipated (side-)effects of tramadol. In addition to the compound-specific clinical implications, it is important to stress that the maturational trends in the elimination processes described can be considered for other compounds (e.g., codeine) that undergo similar elimination routes.
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Affiliation(s)
- Karel Allegaert
- Neonatal Intensive Care Unit, University Hospitals Leuven, Belgium.
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Allegaert K, Stamer U, Anderson B, Holford S, Rochette A, Troconiz I, Pedersen R, Holford N. Tramadol and O-demethyltramadol disposition in humans: a pooled study. Crit Care 2011. [PMCID: PMC3067021 DOI: 10.1186/cc9767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Mak WY, Yuen V, Irwin M, Hui T. Pharmacotherapy for acute pain in children: current practice and recent advances. Expert Opin Pharmacother 2011; 12:865-81. [PMID: 21254863 DOI: 10.1517/14656566.2011.542751] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Acute pain in children may be undertreated. Improved understanding of developmental neurobiology and paediatric pharmacokinetics should facilitate better management of pharmacotherapy. The objective of this review is to discuss current paediatric practice and recent advances with these analgesic agents by using an evidence-based approach. AREAS COVERED Using PubMed an extensive literature review was conducted on the commonly used analgesic agents in children from 2000 to April 2010. EXPERT OPINION A multimodal analgesic regimen provides better pain control and functional outcome in children. The choice of pharmacological treatment is determined by the severity and type of pain. However, more research and evidence is required to determine the optimal drug combinations.
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Affiliation(s)
- Wai Yin Mak
- Queen Mary Hospital-Anaesthesiology, F2 Queen Mary Hospital, 102 Pokfulam Road, Hong Kong.
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Anderson BJ, Allegaert K. The pharmacology of anaesthetics in the neonate. Best Pract Res Clin Anaesthesiol 2010; 24:419-31. [DOI: 10.1016/j.bpa.2010.02.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Abstract
Target-controlled infusion (TCI) pumps currently do not satisfactorily cater for the pediatric population, particularly for those under 5 years. Growth and development are two major aspects of children not readily apparent in adults, and these two aspects influence clearance (CL) and volume of distribution (V). In simple terms, V determines initial dose, and CL determines infusion rate at steady state. Three major covariates (size, age, and organ function) contribute to parameter variability in children. Size can be standardized for clearance in a 70-kg person using the allometric (3/4) power model. Remifentanil, a drug cleared by hydrolysis, can be modeled in all age groups by simple application of this model using a standardized clearance of 2790 ml x min(-1) for a 70-kg person. Allometry alone is insufficient to predict clearance in neonates and infants from adult parameters for most drugs used in anesthesia. The addition of a model describing maturation is required. The sigmoid Emax or Hill model has been found useful for describing this maturation process. Propofol maturation has been described with a mature clearance of 1.83 l x min(-1) x 70 kg(-1), a maturation half-time (TM(50)) of 44 weeks and a Hill coefficient of 4.9. Organ function also affects clearance, and propofol clearance is reduced in neonates and infants after cardiac surgery. Although pharmacokinetics (PK) in children is receiving increasing attention and is eminently programmable into a TCI device, pharmacodynamic (PD) measures in children remain poorly defined, partly because the depth of anesthesia monitoring are inadequate. Both PK and PD are necessary for safe use of TCI pumps.
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Affiliation(s)
- Brian J Anderson
- Department of Anaesthesiology, University of Auckland, Auckland, New Zealand.
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Tremlett M, Anderson BJ, Wolf A. Pro-con debate: is codeine a drug that still has a useful role in pediatric practice? Paediatr Anaesth 2010; 20:183-94. [PMID: 20059720 DOI: 10.1111/j.1460-9592.2009.03234.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Lötsch J, Geisslinger G, Tegeder I. Genetic modulation of the pharmacological treatment of pain. Pharmacol Ther 2009; 124:168-84. [DOI: 10.1016/j.pharmthera.2009.06.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Accepted: 06/22/2009] [Indexed: 12/15/2022]
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Abstract
PURPOSE OF REVIEW Toxicity concerns and awareness during anesthesia issues continue to concern pediatric anesthesiologists. Most developmental pharmacokinetic, pharmacodynamic and pharmacogenomic changes occur within the first year of life. Understanding these early changes can improve drug use in this cohort. RECENT FINDINGS Growth and development are two major aspects of children not readily apparent in adults. Clearance in the pediatric population should be investigated using models that describe size, maturation and organ function influences. Glucuronide conjugation (hepatic phase II process) mirrors glomerular filtration maturation over the first year of life. Phase 1 processes appear more rapid, and differences attributable to single nuclear polymorphisms may be obvious by the end of the 4-week neonatal period in term infants.Pharmacodynamic differences in infancy remain poorly defined, and neonatal pharmacokinetic-pharmacodynamic analyses that might elucidate such differences are few, partly because of a paucity of effective pharmacodynamic measures. SUMMARY Mechanistic models create a framework for the study of pharmacokinetic changes in infancy. Understanding these changes allows a target concentration approach to therapy and potential for reduced toxicity. The target concentration may be undefined because of a paucity of effect measures.
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Current World Literature. Curr Opin Anaesthesiol 2009; 22:539-43. [DOI: 10.1097/aco.0b013e32832fa02c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Allegaert K, Veyckemans F, Tibboel D. Clinical practice: analgesia in neonates. Eur J Pediatr 2009; 168:765-70. [PMID: 19221790 DOI: 10.1007/s00431-009-0932-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Accepted: 01/20/2009] [Indexed: 12/26/2022]
Abstract
Effective management of pain remains an important indicator of the quality of care provided to neonates. Since the review of McIntosh in this journal over a decade ago, an extensive number of papers on assessment, prevention, and treatment of pain have been reported. In addition, preclinical insights into neurodevelopmental aspects of pain processing and the neuro-apoptotic effects of analgesics and sedatives were unveiled. Based on the newly collected evidence, the practice of "one-drug, one dose and one treatment fits all" became obsolete, necessitating a more individualized analgesia, based on non-pharmacological and pharmacological therapies and preventive strategies for effective management of neonatal pain. The progress made is impressive, but the current major challenge is to implement the available knowledge in clinical care. Future research should therefore focus on the evaluation of the effectiveness of non-opioid and moderately potent opioids compared to morphine and should also describe the methods to facilitate effective implementation. Finally, there is an extensive field of procedural techniques that need to be evaluated on their pain related response.
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Affiliation(s)
- Karel Allegaert
- Neonatal Intensive Care Unit, Division of Woman and Child, University Hospital, Leuven, Belgium.
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Bressolle F, Rochette A, Khier S, Dadure C, Ouaki J, Capdevila X. Population pharmacokinetics of the two enantiomers of tramadol and O -demethyl tramadol after surgery in children. Br J Anaesth 2009; 102:390-9. [DOI: 10.1093/bja/aen405] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Fitzgerald M, Walker SM. Infant pain management: a developmental neurobiological approach. ACTA ACUST UNITED AC 2009; 5:35-50. [DOI: 10.1038/ncpneuro0984] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2008] [Accepted: 10/31/2008] [Indexed: 12/21/2022]
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Ince I, de Wildt SN, Tibboel D, Danhof M, Knibbe CAJ. Tailor-made drug treatment for children: creation of an infrastructure for data-sharing and population PK-PD modeling. Drug Discov Today 2008; 14:316-20. [PMID: 19059496 DOI: 10.1016/j.drudis.2008.11.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 10/29/2008] [Accepted: 11/10/2008] [Indexed: 10/21/2022]
Abstract
Rational dosing guidelines for drugs in pediatrics are urgently needed. To develop these guidelines, we use population pharmacokinetic-pharmacodynamic (PK-PD) modeling and simulation by: (i) optimization of clinical trial designs based on preliminary data; (ii) development and internal validation of population PK-PD models using sparse data; (iii) external validation using independent data; and (iv) prospective clinical evaluation. Optimized dosing regimens for specific drugs may then serve as a basis to develop dosing guidelines for existing or newly developed drugs with similar disposition and/or effect. In addition to modeling of drug disposition (PK) pathways, we emphasize the need for modeling of effect (PD) pathways and the use of a multidisciplinary infrastructure for data-sharing.
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Affiliation(s)
- Ibrahim Ince
- Department of Pediatric Surgery, Erasmus MC Sophia Children's Hospital, Rotterdam, The Netherlands
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Allegaert K, Vancraeynest J, Rayyan M, de Hoon J, Cossey V, Naulaers G, Verbesselt R. Urinary propofol metabolites in early life after single intravenous bolus. Br J Anaesth 2008; 101:827-831. [DOI: 10.1093/bja/aen276] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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Abstract
Significant advances in the assessment and management of acute pain in children have been made, and are supported by an increase in the availability and accessibility of evidence-based data. However, methodological and practical issues in the design and performance of clinical paediatric trials limit the quantity, and may influence the quality, of current data, which lags behind that available for adult practice. Collaborations within research networks, which incorporate both preclinical and clinical studies, may increase the feasibility and specificity of future trials. In early life, the developing nervous system responds differently to pain, analgesia, and injury, resulting in effects not seen in later life and which may have long-term consequences. Translational laboratory studies further our understanding of developmental changes in nociceptor pathway structure and function, analgesic pharmacodynamics, and the impact of different forms of injury. Chronic pain in children has a negative impact on quality of life, resulting in social and emotional consequences for both the child and the family. Despite age-related differences in many chronic pain conditions, such as neuropathic pain, management in children is often empirically based on data from studies in adults. There is a major need for further clinical research, training of health-care providers, and increased resources, to improve management and outcomes for children with chronic pain.
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Affiliation(s)
- S M Walker
- Portex Department of Anaesthesia, UCL Institute of Child Health and Great Ormond Street Hospital NHS Trust, 30 Guilford Street, London WC1N 1EH, UK.
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