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Rieder MJ, Elzagallaai AA. Pharmacogenomics in Children. Methods Mol Biol 2022; 2547:569-593. [PMID: 36068477 DOI: 10.1007/978-1-0716-2573-6_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Historically genetics has not been considered when prescribing drugs for children. However, it is clear that genetics are not only an important determinant of disease in children but also of drug response for many important drugs that are core agents used in the therapy of common problems in children. Advances in therapy and in the ethical construct of children's research have made pharmacogenomic assessment for children much easier to pursue. It is likely that pharmacogenomics will become part of the therapeutic decision-making process for children, notably in areas such as childhood cancer where weighing benefits and risks of therapy is crucial.
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Affiliation(s)
- Michael J Rieder
- Division of Paediatric Clinical Pharmacology, Department of Paediatrics, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada.
| | - Abdelbaset A Elzagallaai
- Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, Western University, London, ON, Canada
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2
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Elzagallaai AA, Carleton BC, Rieder MJ. Pharmacogenomics in Pediatric Oncology: Mitigating Adverse Drug Reactions While Preserving Efficacy. Annu Rev Pharmacol Toxicol 2020; 61:679-699. [PMID: 32976737 DOI: 10.1146/annurev-pharmtox-031320-104151] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cancer is the leading cause of death in American children older than 1 year of age. Major developments in drugs such as thiopurines and optimization in clinical trial protocols for treating cancer in children have led to a remarkable improvement in survival, from approximately 30% in the 1960s to more than 80% today. Short-term and long-term adverse effects of chemotherapy still affect most survivors of childhood cancer. Pharmacogenetics plays a major role in predicting the safety of cancer chemotherapy and, in the future, its effectiveness. Treatment failure in childhood cancer-due to either serious adverse effects that limit therapy or the failure of conventional dosing to induce remission-warrants development of new strategies for treatment. Here, we summarize the current knowledge of the pharmacogenomics of cancer drug treatment in children and of statistically and clinically relevant drug-gene associations and the mechanistic understandings that underscore their therapeutic value in the treatment of childhood cancer.
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Affiliation(s)
- Abdelbaset A Elzagallaai
- Department of Pediatrics, Schulich School of Medicine and Dentistry, Western University, London, Ontario N6A 3M7, Canada;
| | - Bruce C Carleton
- Division of Translational Therapeutics, Department of Pediatrics, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada.,Pharmaceutical Outcomes Programme, BC Children's Hospital, Vancouver, British Columbia V5Z 4H4, Canada.,BC Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada
| | - Michael J Rieder
- Department of Pediatrics, Schulich School of Medicine and Dentistry, Western University, London, Ontario N6A 3M7, Canada;
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3
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Ye PP, Zheng Y, Du B, Liu XT, Tang BH, Kan M, Zhou Y, Hao GX, Huang X, Su LQ, Wang WQ, Yu F, Zhao W. First dose in neonates: pharmacokinetic bridging study from juvenile mice to neonates for drugs metabolized by CYP3A. Xenobiotica 2020; 50:1275-1284. [PMID: 32400275 DOI: 10.1080/00498254.2020.1768454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
First dose prediction is challenging in neonates. Our objective in this proof-of-concept study was to perform a pharmacokinetic (PK) bridging study from juvenile mice to neonates for drugs metabolized by CYP3A. We selected midazolam and clindamycin as model drugs. We developed juvenile mice population PK models using NONMEM. The PK parameters of these two drugs in juvenile mice were used to bridge PK parameters in neonates using different correction methods. The bridging results were evaluated by the fold-error of 0.5- to 1.5-fold. Simple allometry with and without a correction factor for maximum lifespan potential could be used for a bridging of clearance (CL) and volume of distribution (Vd), respectively, from juvenile mice to neonates. Simulation results demonstrated that for midazolam, 100% of clinical studies for which both the predictive CL and Vd were within 0.5- to 1.5-fold of the observed. For clindamycin, 75% and 100% of clinical studies for which the predictive CL and Vd were within 0.5- to 1.5-fold of the observed. A PK bridging of drugs metabolized by CYP3A is feasible from juvenile mice to neonates. It could be a complement to the ADE and PBPK models to support the first dose in neonates.
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Affiliation(s)
- Pan-Pan Ye
- Department of Clinical Pharmacy, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China.,Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University, Jinan, China
| | - Yi Zheng
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Bin Du
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xi-Ting Liu
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Bo-Hao Tang
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Min Kan
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Yue Zhou
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Guo-Xiang Hao
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xin Huang
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University, Jinan, China
| | - Le-Qun Su
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University, Jinan, China
| | - Wen-Qi Wang
- Clinical Research Center, The First Affiliated Hospital of Shandong First Medical University, Jinan, China
| | - Feng Yu
- Department of Clinical Pharmacy, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Wei Zhao
- Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University, Jinan, China.,Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China.,Clinical Research Center, The First Affiliated Hospital of Shandong First Medical University, Jinan, China.,Department of Pediatrics, The First Affiliated Hospital of Shandong First Medical University, Jinan, China
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Völler S, Flint RB, Beggah F, Reiss I, Andriessen P, Zimmermann LJI, van den Anker JN, Liem KD, Koch BCP, de Wildt S, Knibbe CAJ, Simons SHP. Recently Registered Midazolam Doses for Preterm Neonates Do Not Lead to Equal Exposure: A Population Pharmacokinetic Model. J Clin Pharmacol 2019; 59:1300-1308. [PMID: 31093992 PMCID: PMC6767398 DOI: 10.1002/jcph.1429] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/04/2019] [Indexed: 11/11/2022]
Abstract
Although midazolam is a frequently used sedative in neonatal intensive care units, its use in preterm neonates has been off-label. Recently, a new dosing advice for midazolam for sedation on intensive care units has been included in the label (0.03 mg/[kg·h] for preterm neonates <32 weeks and 0.06 mg/[kg·h] for neonates >32 weeks). Concentration-time data of a prospective multicenter study (29 patients, median gestational age 26.7 [range 24.0-31.1 weeks]) were combined with previously published data (26 patients, median gestational age 28.1 [range 26.3-33.6 weeks]), and a population pharmacokinetic model describing the maturation of midazolam pharmacokinetics was developed in NONMEM 7.3. Clearance was 73.7 mL/h for a neonate weighing 1.1 kg and changed nonlinearly with body weight (exponent 1.69). Volume of distribution increased linearly with body weight and was 1.03 L for a neonate weighing 1.1 kg. Simulations of the newly registered dosing show considerable differences in steady-state concentrations in preterm neonates. To reach similar steady-state concentrations of 400 µg/mL (±100 µg/mL), a dose of 0.03 mg/(kg·h) is adequate for neonates ≥1 kg and ≤2 kg but would have to be reduced to 0.02 mg/(kg·h) (-33%) in neonates <1 kg and increased to 0.04 mg/(kg·h) (+33%) in neonates weighing >2 kg and ≤2.5 kg. The impact of the observed differences in exposure is difficult to assess because no target concentrations have yet been defined for midazolam, but the current analysis shows that one should be cautious in giving dosage advice based on historical data with a lack of reliable pharmacokinetic and effect data.
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Affiliation(s)
- Swantje Völler
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.,Department of Pediatrics, Division of Neonatology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Robert B Flint
- Department of Pediatrics, Division of Neonatology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands.,Department of Pharmacy, Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Pharmacy, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Fouzi Beggah
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.,Université de Montpellier, Montpellier, France
| | - Irwin Reiss
- Department of Pediatrics, Division of Neonatology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Peter Andriessen
- Department of Pediatrics, Division of Neonatology, Máxima Medical Center, Veldhoven, The Netherlands
| | - Luc J I Zimmermann
- Department of Pediatrics, Maastricht University Medical Center, School of Oncology and Developmental Biology, School of Mental Health and Neuroscience, Maastricht, The Netherlands
| | - John N van den Anker
- Intensive Care and Department of Pediatric Surgery, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands.,Division of Clinical Pharmacology, Children's National Health System, Washington, DC, USA.,Division of Pediatric Pharmacology and Pharmacometrics, University of Basel Children's Hospital, Basel, Switzerland
| | - Kian D Liem
- Department of Pediatrics, Division of Neonatology, Radboud, University Medical Center, Nijmegen, The Netherlands
| | - Birgit C P Koch
- Department of Pharmacy, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Saskia de Wildt
- Intensive Care and Department of Pediatric Surgery, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands.,Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Catherijne A J Knibbe
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Center for Drug Research, Leiden University, Leiden, The Netherlands.,Department of Clinical Pharmacy, St. Antonius Hospital, Nieuwegein, The Netherlands
| | - Sinno H P Simons
- Department of Pediatrics, Division of Neonatology, Erasmus MC-Sophia Children's Hospital, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Yozawitz E, Stacey A, Pressler RM. Pharmacotherapy for Seizures in Neonates with Hypoxic Ischemic Encephalopathy. Paediatr Drugs 2017; 19:553-567. [PMID: 28770451 DOI: 10.1007/s40272-017-0250-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Seizures are common in neonates with moderate and severe hypoxic ischemic encephalopathy (HIE) and are associated with worse outcomes, independent of HIE severity. In contrast to adults and older children, no new drugs have been licensed for treatment of neonatal seizures over the last 50 years, because of a lack of controlled clinical trials. Hence, many antiseizure medications licensed in older children and adults are used off-label for neonatal seizure, which is associated with potential risks of adverse effects during a period when the brain is particularly vulnerable. Phenobarbital is worldwide the first-line drug and is considered standard of care, although there is a limited evidence base for its efficacy. Second-line agents include phenytoin, benzodiazepines, levetiracetam, and lidocaine. These drugs are discussed in more detail along with two emerging drugs (bumetanide and topiramate). More safety, pharmacokinetic, and efficacy data are needed from well-designed clinical trials to develop safe and effective antiseizure regimes for the treatment of neonatal seizures in HIE.
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Affiliation(s)
- Elissa Yozawitz
- Department of Neurology and Pediatrics, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Arthur Stacey
- UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK
| | - Ronit M Pressler
- Department of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, Great Ormond Street, London, WC1N 3JH, UK. .,Clinical Neurosciences, UCL- Great Ormond Street Institute of Child Health, 30 Guilford Street, London, WC1N 1EH, UK.
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Clinical pharmacology of midazolam in neonates and children: effect of disease-a review. Int J Pediatr 2014; 2014:309342. [PMID: 24696691 PMCID: PMC3948203 DOI: 10.1155/2014/309342] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 12/26/2013] [Indexed: 12/04/2022] Open
Abstract
Midazolam is a benzodiazepine with rapid onset of action and short duration of effect. In healthy neonates the half-life (t1/2) and the clearance (Cl) are 3.3-fold longer and 3.7-fold smaller, respectively, than in adults. The volume of distribution (Vd) is 1.1 L/kg both in neonates and adults. Midazolam is hydroxylated by CYP3A4 and CYP3A5; the activities of these enzymes surge in the liver in the first weeks of life and thus the metabolic rate of midazolam is lower in neonates than in adults. Midazolam acts as a sedative, as an antiepileptic, for those infants who are refractory to standard antiepileptic therapy, and as an anaesthetic. Information of midazolam as an anaesthetic in infants are very little. Midazolam is usually administered intravenously; when minimal sedation is required, intranasal administration of midazolam is employed. Disease affects the pharmacokinetics of midazolam in neonates; multiple organ failure reduces the Cl of midazolam and mechanical ventilation prolongs the t1/2 of this drug. ECMO therapy increases t1/2, Cl, and Vd of midazolam several times. The adverse effects of midazolam in neonates are scarce: pain, tenderness, and thrombophlebitis may occur. Respiratory depression and hypotension appear in a limited percentage of infants following intravenous infusion of midazolam. In conclusion, midazolam is a safe and effective drug which is employed as a sedative, as antiepileptic agent, for infants who are refractory to standard antiepileptic therapy, and as an anaesthetic.
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Ferraresso M, Belingheri M, Turolo S, Ghio L, Tirelli AS, Grillo P, Lepore M, Edefonti A. Long-term effects of ABCB1 and SXR SNPs on the systemic exposure to cyclosporine in pediatric kidney transplant patients. Pharmacogenomics 2013; 14:1605-13. [DOI: 10.2217/pgs.13.148] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Aim: Cyclosporine is characterized by a wide interindividual variability in its pharmacokinetics. The objective of this study was to evaluate the effects of ABCB1 and SXR SNPs on cyclosporine exposure in a group of kidney transplant patients followed up from childhood to adulthood. Patients & methods: Recipients were genotyped for ABCB1 C1236T, G2677T/A and C3435T, and for SXR RS3842689 and A7635G. Dose-adjusted trough levels and weight-adjusted daily doses were compared among patients according to allelic status by a generalized estimation equation approach that allows longitudinal data analyses. Results: A genotype-dependent effect was found in all ABCB1 genotypes and in one of the SXR SNPs. This effect was particularly evident for the TT genotype of the ABCB1 G2677T/A SNP, the TT genotype of the ABCB1 C3435T SNP and for heterozygotes of the deletion of 6 bp in the promoter region of SXR. Conclusion: The presence of specific ABCB1 and SXR SNPs could significantly affect cyclosporine exposure during a kidney transplant patient’s development from childhood to adulthood in a time-dependent fashion. Original submitted 3 May 2013; Revision submitted 25 July 2013
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Affiliation(s)
- Mariano Ferraresso
- Department of Clinical Sciences & Community Health, University of Milan, Milan, Italy
- Division of General & Vascular Surgery, St Joseph Hospital, 20122, Milan, Italy
| | - Mirco Belingheri
- Division of Pediatric Nephology & Kidney Transplantation, Ca’ Granda Foundation, Ospedale Maggiore, IRCCS, Milan, Italy
| | - Stefano Turolo
- Laboratory of Clinical Chemistry & Microbiology, Ca’ Granda Foundation, Ospedale Maggiore, IRCCS, Milan, Italy
| | - Luciana Ghio
- Division of Pediatric Nephology & Kidney Transplantation, Ca’ Granda Foundation, Ospedale Maggiore, IRCCS, Milan, Italy
| | - Amedea Silvia Tirelli
- Laboratory of Clinical Chemistry & Microbiology, Ca’ Granda Foundation, Ospedale Maggiore, IRCCS, Milan, Italy
| | - Paolo Grillo
- Epidemiology Unit, Department of Occupational & Environmental Health, Ca’ Granda Foundation, Ospedale Maggiore, IRCCS, Milan, Italy
| | - Marta Lepore
- Division of Pediatric Nephology & Kidney Transplantation, Ca’ Granda Foundation, Ospedale Maggiore, IRCCS, Milan, Italy
| | - Alberto Edefonti
- Division of Pediatric Nephology & Kidney Transplantation, Ca’ Granda Foundation, Ospedale Maggiore, IRCCS, Milan, Italy
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Increased Cyclosporin A Sensitivity In Vivo in Pediatric Renal Transplant Recipients Compared With Adults. Ther Drug Monit 2012; 34:554-60. [DOI: 10.1097/ftd.0b013e3182697655] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Inosine monophosphate dehydrogenase activity in paediatrics: age-related regulation and response to mycophenolic acid. Eur J Clin Pharmacol 2012; 68:913-22. [DOI: 10.1007/s00228-011-1203-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Accepted: 12/20/2011] [Indexed: 10/14/2022]
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Tönshoff B, David-Neto E, Ettenger R, Filler G, van Gelder T, Goebel J, Kuypers DRJ, Tsai E, Vinks AA, Weber LT, Zimmerhackl LB. Pediatric aspects of therapeutic drug monitoring of mycophenolic acid in renal transplantation. Transplant Rev (Orlando) 2011; 25:78-89. [PMID: 21454065 DOI: 10.1016/j.trre.2011.01.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 01/09/2011] [Indexed: 11/24/2022]
Abstract
Mycophenolate mofetil (MMF) is widely used for maintenance immunosuppressive therapy in pediatric renal and heart transplant recipients. Children undergo developmental changes (ontogeny) of drug disposition, which may affect drug metabolism of the active compound mycophenolic acid (MPA). Therefore, a detailed characterization of MPA pharmacokinetics and pharmacodynamics in this patient population is required. In general, the overall efficacy and tolerability of MMF in pediatric patients appear to be comparable with those in adults, except for a higher prevalence of gastrointestinal adverse effects in children younger than 6 years. The currently recommended dose in pediatric patients with concomitant cyclosporine is 1200 mg/m(2) per day in 2 divided doses; the recommended MMF dose with concomitant tacrolimus or without a concurrent calcineurin inhibitor is 900 mg/m(2) per day in 2 divided doses. Recent data suggest that fixed MMF dosing results in MPA underexposure (MPA-area under the concentration-time curve (AUC(0-12)), <30 mg × h/L) early posttransplant in approximately 60% of patients. To achieve adequate MPA exposure in most patients, an initial MMF dose of 1800 mg/m(2) per day with concomitant cyclosporine and 1200 mg/m(2) per day with concomitant tacrolimus for the first 2 to 4 weeks posttransplant has been suggested. As in adults, there is an approximately 10-fold variability in dose-normalized MPA-AUC(0-12) values between pediatric patients after renal transplantation, strengthening the argument for concentration-controlled dosing of the drug. Although the clinical utility of therapeutic drug monitoring of MPA for graft outcome and patient survival is still controversial, potential indications are the avoidance of underimmunosuppression, particularly in patients with high immunologic risk in the initial period posttransplant, in patients who are treated with protocols that explore the possibilities of calcineurin inhibitor minimization, withdrawal or even complete avoidance, and steroid withdrawal or avoidance regimens that might also benefit from intensified therapeutic drug monitoring of MPA. An additional indication especially in adolescent patients is the monitoring of drug adherence. Therapeutic drug monitoring of MPA in pediatric solid organ transplantation using limited sampling strategies is preferable over drug dosing based on trough level monitoring only. Several validated pediatric limited sampling strategies are available. Clearly, more research is required to determine whether pediatric patients will benefit from therapeutic drug monitoring of MPA for long-term maintenance immunosuppression with MMF.
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Affiliation(s)
- Burkhard Tönshoff
- University Children's Hospital Heidelberg, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany.
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de Wildt SN, Kearns GL, Murry DJ, Koren G, van den Anker JN. Ontogeny of midazolam glucuronidation in preterm infants. Eur J Clin Pharmacol 2009; 66:165-70. [PMID: 19838691 PMCID: PMC2805794 DOI: 10.1007/s00228-009-0741-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Accepted: 09/17/2009] [Indexed: 11/25/2022]
Abstract
Purpose In preterm infants, the biotransformation of midazolam (M) to 1-OH-midazolam (OHM) by cytochrome P450 3A4 (CYP3A4) is developmentally immature, but it is currently unknown whether the glucuronidation of OHM to 1-OH-midazolam glucuronide (OHMG) is also decreased. The aim of our study was to investigate the urinary excretion of midazolam and its metabolites OHM and OHMG in preterm neonates following the intravenous (IV) or oral (PO) administration of a single M dose. Methods Preterm infants (post-natal age 3–13 days, gestational age 26–34 4/7 weeks) scheduled to undergo a stressful procedure received a 30-min IV infusion (n = 15) or a PO bolus dose (n= 7) of 0.1 mg/kg midazolam. The percentage of midazolam dose excreted in the urine as M, OHM and OHMG up to 6 h post-dose was determined. Results The median percentage of the midazolam dose excreted as M, OHM and OHMG in the urine during the 6-h interval after the IV infusion was 0.44% (range 0.02–1.39%), 0.04% (0.01–0.13%) and 1.57% (0.36–7.7%), respectively. After administration of the PO bolus dose, the median percentage of M, OHM and OHMG excreted in the urine was 0.11% (0.02–0.59%), 0.02% (0.00–0.10%) and 1.69% (0.58–7.31%), respectively. The proportion of the IV midazolam dose excreted as OHMG increased significantly with postconceptional age (r = 0.73, p < 0.05). Conclusion The glucuronidation of OHM appears immature in preterm infants less than 2 weeks of age. The observed increase in urinary excretion of OHMG with postconceptional age likely reflects the combined maturation of glucuronidation and renal function.
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Affiliation(s)
- Saskia N de Wildt
- Department of Paediatrics and Paediatric Surgery, Erasmus MC Sophia Children's Hospital, Rotterdam, The Netherlands.
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12
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de Wildt SN, Ito S, Koren G. Challenges for drug studies in children: CYP3A phenotyping as example. Drug Discov Today 2008; 14:6-15. [PMID: 18721895 DOI: 10.1016/j.drudis.2008.07.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Revised: 07/20/2008] [Accepted: 07/23/2008] [Indexed: 10/21/2022]
Abstract
A paucity of data exists on the disposition and effect of drugs in young children. This information gap can be reduced by elucidating developmental principles of absorption, distribution, metabolism and excretion (ADME) in vivo. Such knowledge might enable the prediction of the disposition of individual drugs in children over the whole pediatric age range. CYP3A, the most abundant human drug metabolizing enzyme, is involved in the metabolism of more than 50% of all marketed drugs. Hence, elucidating the developmental pattern of CYP3A in relation to genetic background, disease and comedications might greatly enhance our knowledge on drug disposition in children. Several methods have been used to determine in vivo CYP3A activity in human adults, while similar studies in children face several ethical, practical and scientific challenges. The aim of this review is to identify these challenges and offer feasible solutions for studying drugs in young children, with an emphasis on CYP3A phenotyping as an example.
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Affiliation(s)
- Saskia N de Wildt
- Division of Clinical Pharmacology and Toxicology, Department of Pediatrics, Hospital for Sick Children, University of Toronto, Toronto, Canada.
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Strolin Benedetti M, Whomsley R, Baltes EL. Differences in absorption, distribution, metabolism and excretion of xenobiotics between the paediatric and adult populations. Expert Opin Drug Metab Toxicol 2006; 1:447-71. [PMID: 16863455 DOI: 10.1517/17425255.1.3.447] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In children, the therapeutic benefits and potential risks associated with drug treatment may be different from those in adults and will depend on the exposure, receptor sensitivity and relationship between effect and exposure. In this paper, key factors undergoing maturational changes accounting for differences in drug metabolism and disposition in the paediatric population compared with adults are reviewed. Gastric and duodenal pH, gastric emptying time, intestinal transit time, secretion and activity of bile and pancreatic fluid, bacterial colonisation and transporters, such as P-glycoprotein (P-gp), are important factors for drug absorption, whereas key factors explaining differences in drug distribution between the paediatric population and adults are organ size, membrane permeability, plasma protein concentration and characteristics, endogenous substances in plasma, total body and extracellular water, fat content, regional blood flow and transporters such as P-gp, which is present not only in the gut, but also in liver, kidney, brain and other tissues. As far as drug metabolism is concerned, important differences have been found in the paediatric population compared with adults both for phase I enzymes (oxidative [e.g., cytochrome P450 (CYP)1A2, and CYP3A7 versus -3A4], reductive and hydrolytic enzymes) and phase II enzymes (e.g., N-methyltransferases and glucuronosyltransferases). Generally, the major enzyme differences observed in comparison with the adult age are in newborn infants, although for some enzymes (e.g., glucuronosyltransferases and other phase II enzymes) important differences still exist between infants and toddlers and adults. Finally, key factors undergoing maturational changes accounting for differences in renal excretion in the paediatric population compared with adults are glomerular filtration and tubular secretion. The ranking of the key factors varies according to the chemical structure and physicochemical properties of the drug examined, as well as to the characteristics of its formulation. It would be important to generate additional information on the developmental aspects of renal P-gp and of other renal transporters, as has been done and is still being done with the different -isozymes involved in drug metabolism.
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Kearns GL, Abdel-Rahman SM, Alander SW, Blowey DL, Leeder JS, Kauffman RE. Developmental pharmacology--drug disposition, action, and therapy in infants and children. N Engl J Med 2003; 349:1157-67. [PMID: 13679531 DOI: 10.1056/nejmra035092] [Citation(s) in RCA: 1481] [Impact Index Per Article: 70.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Gregory L Kearns
- Department of Pediatrics, University of Missouri at Kansas City, Kansas City, Mo, USA.
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