Medical Pharmacology Commons^™

A Population Pharmacokinetic Model For Simvastatin And Its Metabolites In Children And Adolescents., Kayode Ogungbenro, Jonathan B. Wagner, Susan M. Abdel-Rahman, J Steven Leeder, Aleksandra Galetin

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PURPOSE: Poor adherence to dietary/behaviour modifications as interventions for hypercholesterolemia in paediatric patients often necessitates the initiation of statin therapy. The aim of this study was to develop a joint population pharmacokinetic model for simvastatin and four metabolites in children and adolescents to investigate sources of variability in simvastatin acid exposure in this patient population, in addition to SLCO1B1 genotype status.

METHODS: Plasma concentrations of simvastatin and its four metabolites, demographic and polymorphism data for OATP1B1 and CYP3A5 were analysed utilising a population pharmacokinetic modelling approach from an existing single oral dose (10 mg < 17 years and 20 mg ≥ 18 years) pharmacokinetic dataset of 32 children and adolescents.

RESULTS: The population PK model included …

Considerations For Implementing Precision Therapeutics For Children., Matthew J. Mclaughlin, Jonathan B. Wagner, Valentina Shakhnovich, Bruce Carleton, J Steven Leeder

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Improving the utilization of pharmacologic agents in the pediatric population yields significant, perhaps life-long, benefits. Genetic factors related to the disposition of a medication or an alteration at the target receptor site contributes to the observed variability of exposure and response between individuals. An additional source of this variability specific to the pediatric population is ontogeny, where age-specific changes during development may require dose adjustments to obtain the same levels of drug exposure and response. With significant improvements in characterizing both the ontogeny and genetic contributions of drug metabolizing enzymes, the time is right to begin placing more emphasis on …

An Open-Label, Single-Dose Study To Evaluate The Safety, Tolerability, Pharmacokinetics, And Pharmacodynamics Of Cinacalcet In Pediatric Subjects Aged 28 Days To < 6 Years With Chronic Kidney Disease Receiving Dialysis., Winnie Y. Sohn, Anthony A. Portale, Isidro B. Salusky, Hao Zhang, Lucy L. Yan, Bella Ertik, Shahnaz Shahinfar, Edward Lee, Bastian Dehmel, Bradley A. Warady

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BACKGROUND: Calcimimetics, shown to control biochemical parameters of secondary hyperparathyroidism (SHPT), have well-established safety and pharmacokinetic profiles in adult end-stage renal disease subjects treated with dialysis; however, such studies are limited in pediatric subjects.

METHODS: In this study, the safety, tolerability, pharmacokinetics (PK), and pharmacodynamics (PD) of cinacalcet were evaluated in children with chronic kidney disease (CKD) and SHPT receiving dialysis. Twelve subjects received a single dose of cinacalcet (0.25 mg/kg) orally or by nasogastric or gastric tube. Subjects were randomized to one of two parathyroid hormone (PTH) and serum calcium sampling sequences: [(1) 2, 8, 48 h; or (2) …

Clinical Pharmacology Of Tisagenlecleucel In B-Cell Acute Lymphoblastic Leukemia., Karen Thudium Mueller, Edward Waldron, Stephan A. Grupp, John E. Levine, Theodore W. Laetsch, Michael A. Pulsipher, Michael W. Boyer, Keith August, Jason Hamilton, Rakesh Awasthi, Andrew M. Stein, Denise Sickert, Abhijit Chakraborty, Bruce L. Levine, Carl H. June, Lori Tomassian, Sweta S. Shah, Mimi Leung, Tetiana Taran, Patricia A. Wood, Shannon L. Maude

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PURPOSE: Tisagenlecleucel is an anti-CD19 chimeric antigen receptor (CAR19) T-cell therapy approved for the treatment of children and young adults with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL).

PATIENTS AND METHODS: We evaluated the cellular kinetics of tisagenlecleucel, the effect of patient factors, humoral immunogenicity, and manufacturing attributes on its kinetics, and exposure-response analysis for efficacy, safety and pharmacodynamic endpoints in 79 patients across two studies in pediatric B-ALL (ELIANA and ENSIGN).

RESULTS: Using quantitative polymerase chain reaction to quantify levels of tisagenlecleucel transgene, responders (N = 62) had ≈2-fold higher tisagenlecleucel expansion in peripheral blood than nonresponders ( …

Efficacy And Safety Of Sparsentan Compared With Irbesartan In Patients With Primary Focal Segmental Glomerulosclerosis: Randomized, Controlled Trial Design (Duet)., Radko Komers, Debbie S. Gipson, Peter Nelson, Sharon Adler, Tarak Srivastava, Vimal K. Derebail, Kevin E. Meyers, Pablo Pergola, Meghan E. Macnally, Jennifer L. Hunt, Alvin Shih, Howard Trachtman

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Introduction: Primary focal segmental glomerulosclerosis (FSGS) is a leading cause of nephrotic syndrome and end-stage renal disease. There are no US Food and Drug Administration-approved therapies for FSGS, and treatment often fails to reduce proteinuria. Endothelin is an important factor in the pathophysiology of podocyte disorders, including FSGS. Sparsentan is a first-in-class, orally active, dual-acting angiotensin receptor blocker (ARB) and highly selective endothelin Type A receptor antagonist. This study is designed to evaluate whether sparsentan lowers proteinuria compared with an ARB alone and has a favorable safety profile in patients with FSGS.

Methods: DUET is a phase 2, randomized, active-control, …

Clinical Pharmacogenetics Implementation Consortium Guideline (Cpic) For Cyp2d6 And Cyp2c19 Genotypes And Dosing Of Tricyclic Antidepressants: 2016 Update., J K. Hicks, K Sangkuhl, J J. Swen, V L. Ellingrod, D J. Müller, K Shimoda, J R. Bishop, E D. Kharasch, T C. Skaar, Andrea Gaedigk, H M. Dunnenberger, T E. Klein, K E. Caudle, J C. Stingl

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No abstract provided.

A Rare Case Of Vascular Ring And Coarctation Of The Aorta In Association With Charge Syndrome., Jonathan B. Wagner, Joshua Q. Knowlton, Peter Pastuszko, Sanket Shah

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A male neonate presented with CHARGE syndrome, a multiorgan genetic disorder involving the Coloboma of the eyes, congenital Heart defects, nasal choanal Atresia, growth and development Retardation, Genitourinary disorders, and Ear anomalies and deafness. Moreover, he had a rare case of vascular ring-consisting of a right aortic arch with retroesophageal brachiocephalic artery-combined with coarctation of the mid-aortic arch. He underwent both vascular ring and aortic arch repair at our institution. To our knowledge, this is the 4th documented case of this exceedingly rare type of aortic arch anomaly combined with aortic arch obstruction. Moreover, it is the first confirmed case …

Impact Of Cyp2d6 Genotype On Amitriptyline Efficacy For The Treatment Of Diabetic Peripheral Neuropathy: A Pilot Study., Mamoonah Chaudhry, Marco Alessandrini, Jacobus Rademan, Tyren M. Dodgen, Francois E. Steffens, Danie G. Van Zyl, Andrea Gaedigk, Michael S. Pepper

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AIM: Therapy with low-dose amitriptyline is commonly used to treat painful diabetic peripheral neuropathy. There is a knowledge gap, however, regarding the role of variable CYP2D6-mediated drug metabolism and side effects (SEs). We aimed to generate pilot data to demonstrate that SEs are more frequent in patients with variant CYP2D6 alleles.

METHOD: To that end, 31 randomly recruited participants were treated with low-dose amitriptyline for painful diabetic peripheral neuropathy and their CYP2D6 gene sequenced.

RESULTS: Patients with predicted normal or ultra-rapid metabolizer phenotypes presented with less SEs compared with individuals with decreased CYP2D6 activity.

CONCLUSION: Hence, CYP2D6 genotype contributes to …

In Vivo Characterization Of Cyp2d6*12, *29 And *84 Using Dextromethorphan As A Probe Drug: A Case Report., Andrea Gaedigk, Greyson P. Twist, Emily G. Farrow, Jennifer Lowry, Sarah E. Soden, Neil A. Miller

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CYP2D6*84 was first described in a Black South African subject, however, its function remains unknown. Astrolabe, a probabilistic scoring tool developed in our laboratory to call genotypes from whole genome sequence, identified CYP2D6*84 in a trio. The father presented with intermediate metabolism when challenged with the CYP2D6 probe drug dextromethorphan (DM/dextrorphan [DX] = 0.0839). Since his second allele, CYP2D6*12, is nonfunctional, the observed activity is derived by CYP2D6*84. This finding suggests that the allele's hallmark P267H causes decreased activity toward DM and that this allele should receive a value of 0.5 for Activity Score calculations. The mother's DM/DX of 0.0543 …

Metabolic And Molecular Insights Into An Essential Role Of Nicotinamide Phosphoribosyltransferase., Li Q. Zhang, Leon Van Haandel, Min Xiong, Peixin Huang, Daniel P. Heruth, Chengpeng Bi, R Gaedigk, Xun Jiang, Ding-You Li, Gerald Wyckoff, Dmitry N. Grigoryev, Li Gao, Linheng Li, Min Wu, J Steven Leeder, Shui Qing Ye

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Nicotinamide phosphoribosyltransferase (NAMPT) is a pleiotropic protein implicated in the pathogenesis of acute respiratory distress syndrome, aging, cancer, coronary heart diseases, diabetes, nonalcoholic fatty liver disease, obesity, rheumatoid arthritis, and sepsis. However, the underlying molecular mechanisms of NAMPT in these physiological and pathological processes are not fully understood. Here, we provide experimental evidence that a Nampt gene homozygous knockout (Nampt-/-) resulted in lethality at an early stage of mouse embryonic development and death within 5-10 days in adult mice accompanied by a 25.24±2.22% body weight loss, after the tamoxifen induction of NamptF/F × Cre mice. These results substantiate that Nampt …

Topical Anaesthetics For Pain Control During Repair Of Dermal Laceration., Baraa O. Tayeb, Anthony Eidelman, Cristy L. Eidelman, Ewan D. Mcnicol, Daniel B. Carr

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BACKGROUND: Topical local anaesthetics provide effective analgesia for patients undergoing numerous superficial procedures, including repair of dermal lacerations. The need for cocaine in topical anaesthetic formulations has been questioned because of concern about adverse effects, thus novel preparations of cocaine-free anaesthetics have been developed. This review was originally published in 2011 and has been updated in 2017.

OBJECTIVES: To assess whether benefits of non-invasive topical anaesthetic application occur at the expense of decreased analgesic efficacy. To compare the efficacy of various single-component or multi-component topical anaesthetic agents for repair of dermal lacerations. To determine the clinical necessity for topical application …

Newborn Sequencing In Genomic Medicine And Public Health., Jonathan S. Berg, Pankaj B. Agrawal, Donald B. Bailey, Alan H. Beggs, Steven E. Brenner, Amy M. Brower, Julie A. Cakici, Ozge Ceyhan-Birsoy, Kee Chan, Flavia Chen, Robert J. Currier, Dmitry Dukhovny, Robert C. Green, Julie Harris-Wai, Ingrid A. Holm, Brenda Iglesias, Galen Joseph, Stephen F. Kingsmore, Barbara A. Koenig, Pui-Yan Kwok, John Lantos, J Steven Leeder, Megan A. Lewis, Amy L. Mcguire, Laura V. Milko, Sean D. Mooney, Richard B. Parad, Stacey Pereira, Josh E. Petrikin, Bradford C. Powell, Cynthia M. Powell, Jennifer M. Puck, Heidi L. Rehm, Neil Risch, Myra Roche, Joseph T. Shieh, Narayanan Veeraraghavan, Michael S. Watson, Laurel K. Willig, Timothy W. Yu, Tiina Urv, Anastasia L. Wise

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The rapid development of genomic sequencing technologies has decreased the cost of genetic analysis to the extent that it seems plausible that genome-scale sequencing could have widespread availability in pediatric care. Genomic sequencing provides a powerful diagnostic modality for patients who manifest symptoms of monogenic disease and an opportunity to detect health conditions before their development. However, many technical, clinical, ethical, and societal challenges should be addressed before such technology is widely deployed in pediatric practice. This article provides an overview of the Newborn Sequencing in Genomic Medicine and Public Health Consortium, which is investigating the application of genome-scale sequencing …

Metronidazole Metabolism In Neonates And The Interplay Between Ontogeny And Genetic Variation., Laura A. Wang, Daniel Gonzalez, J Steven Leeder, Rachel F. Tyndale, Robin E. Pearce, Daniel K. Benjamin, Gregory L. Kearns, Michael Cohen-Wolkowiez, Best Pharmaceuticals For Children Act-Pediatric Trials Network Steering Committee

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No abstract provided.

Prediction Of Cyp2d6 Phenotype From Genotype Across World Populations., Andrea Gaedigk, Katrin Sangkuhl, Michelle Whirl-Carrillo, Teri Klein, J Steven Leeder

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PURPOSE: Owing to its highly polymorphic nature and major contribution to the metabolism and bioactivation of numerous clinically used drugs, CYP2D6 is one of the most extensively studied drug-metabolizing enzymes and pharmacogenes. CYP2D6 alleles confer no, decreased, normal, or increased activity and cause a wide range of activity among individuals and between populations. However, there is no standard approach to translate diplotypes into predicted phenotype.

METHODS: We exploited CYP2D6 allele-frequency data that have been compiled for Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines (>60,000 subjects, 173 reports) in order to estimate genotype-predicted phenotype status across major world populations based on …

A Novel Compound-Heterozygous Epithelial Cell Adhesion Molecule Mutation In Tufting Enteropathy., Valentina Shakhnovich, Darrell Dinwiddie, Amber Hildreth, Thomas M. Attard, Stephen Kingsmore

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No abstract provided.

Bioactivation Of Trimethoprim To Protein-Reactive Metabolites In Human Liver Microsomes., Jennifer Goldman, Yakov M. Koen, Steven A. Rogers, Kelin Li, J Steven Leeder, Robert P. Hanzlik

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The formation of drug-protein adducts via metabolic activation and covalent binding may stimulate an immune response or may result in direct cell toxicity. Protein covalent binding is a potentially pivotal step in the development of idiosyncratic adverse drug reactions (IADRs). Trimethoprim (TMP)-sulfamethoxazole (SMX) is a combination antibiotic that commonly causes IADRs. Recent data suggest that the contribution of the TMP component of TMP-SMX to IADRs may be underappreciated. We previously demonstrated that TMP is bioactivated to chemically reactive intermediates that can be trapped in vitro by N-acetyl cysteine (NAC), and we have detected TMP-NAC adducts (i.e., mercapturic acids) in the …

Ontogeny Of Hepatic Drug Transporters As Quantified By Lc-Ms/Ms Proteomics., B Prasad, Andrea Gaedigk, M Vrana, R Gaedigk, J Steven Leeder, L Salphati, X Chu, G Xiao, Ceca Hop, R Evers, L Gan, J D Unadkat

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Protein expression of major hepatic uptake and efflux drug transporters in human pediatric (n = 69) and adult (n = 41) livers was quantified by liquid chromatography / tandem mass spectroscopy (LC-MS/MS). Transporter protein expression of OCT1, OATP1B3, P-gp, and MRP3 was age-dependent. Particularly, significant differences were observed in transporter expression (P < 0.05) between the following age groups: neonates vs. adults (OCT1, OATP1B3, P-gp), neonates or infants vs. adolescents and/or adults (OCT1, OATP1B3, and P-gp), infants vs. children (OATP1B3 and P-gp), and adolescents vs. adults (MRP3). OCT1 showed the largest increase, of almost 5-fold, in protein expression with age. Ontogenic expression of OATP1B1 was confounded by genotype and was revealed only in livers harboring SLCO1B1*1A/*1A. In livers >1 year, tissues harboring SLCO1B1*14/*1A showed 2.5-fold higher (P < 0.05) protein expression than SLCO1B1*15/*1A. Integration of these ontogeny data in physiologically based pharmacokinetic (PBPK) models will be a crucial step in predicting hepatic drug disposition in children.

Pediatric Statin Administration: Navigating A Frontier With Limited Data., Jonathan B. Wagner, Susan M. Abdel-Rahman

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Increasingly, children and adolescents with dyslipidemia qualify for pharmacologic intervention. As they are for adults, 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (statins) are the mainstay of pediatric dyslipidemia treatment when lifestyle modifications have failed. Despite the overall success of these drugs, the magnitude of variability in dose-exposure-response profiles contributes to adverse events and treatment failure. In children, the cause of treatment failures remains unclear. This review describes the updated guidelines for screening and management of pediatric dyslipidemia and statin disposition pathway to assist the provider in recognizing scenarios where alterations in dosage may be warranted to meet patients' specific needs.

Constellation: A Tool For Rapid, Automated Phenotype Assignment Of A Highly Polymorphic Pharmacogene,, Greyson P. Twist, Andrea Gaedigk, Neil A. Miller, Emily G. Farrow, Laurel K. Willig, Darrell L. Dinwiddie, Josh E. Petrikin, Sarah E. Soden, Suzanne Herd, Margaret Gibson, Julie A. Cakici, Amanda K. Riffel, J Steven Leeder, Deendayal Dinakarpandian, Stephen F. Kingsmore

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An important component of precision medicine-the use of whole-genome sequencing (WGS) to guide lifelong healthcare-is electronic decision support to inform drug choice and dosing. To achieve this, automated identification of genetic variation in genes involved in drug absorption, distribution, metabolism, excretion and response (ADMER) is required. CYP2D6 is a major enzyme for drug bioactivation and elimination. CYP2D6 activity is predominantly governed by genetic variation; however, it is technically arduous to haplotype. Not only is the nucleotide sequence of CYP2D6 highly polymorphic, but the locus also features diverse structural variations, including gene deletion, duplication, multiplication events and rearrangements with the nonfunctional, …

Oseltamivir-Warfarin Interaction In Hypoplastic Left Heart Syndrome: Case Report And Review., Jonathan B. Wagner, Susan M. Abdel-Rahman

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An 8-year-old boy with hypoplastic left heart syndrome with a previous history of thrombosis within the inferior vena cava receiving stable warfarin dosing for anticoagulation was diagnosed with influenza B. He was subsequently placed on oseltamivir therapy according to the Centers for Disease Control and Prevention clinical practice guidelines. During the hospitalization, his international normalized ratio steadily increased to supratherapeutic levels and returned to baseline after discontinuation of oseltamivir therapy. This case represents a drug-drug interaction that has not been previously reported in children or adolescents. An extensive review of the pharmacokinetic and pharmacodynamic literature did not uncover a definitive …

Cyp2d7 Sequence Variation Interferes With Taqman Cyp2d6 (*) 15 And (*) 35 Genotyping., Amanda K. Riffel, Mehdi Dehghani, Toinette Hartshorne, Kristen C. Floyd, J Steven Leeder, Kevin P. Rosenblatt, Andrea Gaedigk

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TaqMan™ genotyping assays are widely used to genotype CYP2D6, which encodes a major drug metabolizing enzyme. Assay design for CYP2D6 can be challenging owing to the presence of two pseudogenes, CYP2D7 and CYP2D8, structural and copy number variation and numerous single nucleotide polymorphisms (SNPs) some of which reflect the wild-type sequence of the CYP2D7 pseudogene. The aim of this study was to identify the mechanism causing false-positive CYP2D6 (*) 15 calls and remediate those by redesigning and validating alternative TaqMan genotype assays. Among 13,866 DNA samples genotyped by the CompanionDx® lab on the OpenArray platform, 70 samples were identified as …

Pupillometry: A Non-Invasive Technique For Pain Assessment In Paediatric Patients., Mark A. Connelly, Jacob T. Brown, Gregory L. Kearns, Rawni A. Anderson, Shawn D. St Peter, Kathleen A. Neville

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OBJECTIVE: Pupillometry has been used to assess pain intensity and response to analgesic medications in adults. The aim of this observational study was to explore proof of concept for the use of this technique in paediatric patients. Changes in pupil parameters before and after opioid exposure also were evaluated.

DESIGN AND SETTING: This was a single-centre, prospective study conducted at an academic paediatric medical centre.

PATIENTS: Children 9-17 years of age undergoing elective surgical correction of pectus excavatum were enrolled into a protocol approved by the human ethical committee (institutional review board).

INTERVENTIONS: Pupil size and reactivity were measured using …

Pediatric Pharmacogenomics: A Systematic Assessment Of Ontogeny And Genetic Variation To Guide The Design Of Statin Studies In Children., Jonathan B. Wagner, J Steven Leeder

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The dose-exposure-response relationship for drugs may differ in pediatric patients compared with adults. Many clinical studies have established drug dose-exposure relationships across the pediatric age spectrum; however, genetic variation was seldom included. This article applies a systematic approach to determine the relative contribution of development and genetic variation on drug disposition and response using HMG-CoA reductase inhibitors as a model. Application of the approach drives the collection of information relevant to understanding the potential contribution of ontogeny and genetic variation to statin dose-exposure-response in children, and identifies important knowledge deficits to be addressed through the design of future studies.

Serum 25-Hydroxyvitamin D Level And Acute-Phase Reaction Following Initial Intravenous Bisphosphonate., Tarak Srivastava, Hongying Dai, Connie J. Haney, Uri S. Alon

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No abstract provided.

Atorvastatin May Have No Effect On Acute Phase Reaction In Children After Intravenous Bisphosphonate Infusion., Tarak Srivastava, Connie J. Haney, Uri S. Alon

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Intravenous bisphosphonate therapy is associated with acute phase reaction characterized by fever and musculoskeletal pain. Bisphosphonates have been shown in vitro to activate gammadeltaT-cells to proliferate and produce cytokines, suggesting a role in acute phase reaction, which can be effectively blocked by statins. We conducted a double-blind randomized crossover placebo controlled study in 12 children (12.1 +/- 4.2 yr; 10 girls and 2 boys) receiving intravenous bisphosphonates to evaluate whether statins can be used to prevent acute phase reaction associated with therapy. Children received two cycles given 3-4 mo apart of intravenous bisphosphonate given on 2 consecutive days in each …