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Braathen MR, Rigby-Jones AE, Ræder J, Spigset O, Heier T. Pharmacokinetics of propofol in severely obese surgical patients. Acta Anaesthesiol Scand 2024; 68:726-736. [PMID: 38481015 DOI: 10.1111/aas.14407] [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] [Received: 06/27/2023] [Revised: 02/23/2024] [Accepted: 02/26/2024] [Indexed: 06/20/2024]
Abstract
BACKGROUND Existing PK models of propofol include sparse data from very obese patients. The aim of this study was to develop a PK model based on standardised surgical conditions and spanning from normal-weight up to, and including, a high number of very obese patients. METHODS Adult patients scheduled for laparoscopic cholecystectomy or bariatric surgery were studied. Anaesthesia was induced with propofol 2 mg/kg adjusted body weight over 2 min followed by 6 mg/kg/h adjusted body weight over 30 min. For the remainder of the operation anaesthesia was maintained with sevoflurane. Remifentanil was dosed according to clinical need. Eight arterial samples were drawn in a randomised block sampling regimen over a span of 24 h. Time-concentration data were analysed by population PK modelling using non-linear mixed-effects modelling. RESULTS Four hundred and seventy four serum propofol concentrations were collected from 69 patients aged 19-60 years with a BMI 21.6-67.3 kg/m2. Twenty one patients had a BMI above 50 kg/m2. A 3-compartment PK model was produced wherein three different body weight descriptors and sex were included as covariates in the final model. Total body weight was found to be a covariate for clearance and Q3; lean body weight for V1, V2 and Q2; predicted normal weight for V3 and sex for V1. The fixed allometric exponent of 0.75 applied to all clearance parameters improved the performance of the model. Accuracy and precision were 1.4% and 21.7% respectively in post-hoc performance evaluation. CONCLUSION We have developed a new PK model of propofol that is suitable for all adult weight classes. Specifically, it is based on data from an unprecedented number of individuals with very high BMI.
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Affiliation(s)
- Martin Rygh Braathen
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Anesthesiology, Division of Critical Care, Oslo University Hospital, Oslo, Norway
| | | | - Johan Ræder
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Anesthesiology, Division of Critical Care, Oslo University Hospital, Oslo, Norway
| | - Olav Spigset
- Department of Clinical Pharmacology, St. Olav University Hospital, Trondheim, Norway
- Department of Clinical and Molecular Medicine, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Tom Heier
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
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2
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Rzasa Lynn RS, Henthorn TK, Zuk J, Hammer GB, Drover DR, Levy RJ, Maxwell LG, Sadhasivam S, Suresh S, Galinkin JL. Multicenter Population Pharmacokinetics of Fentanyl in Neonatal Surgical Patients Using Dried Blood Spot Specimen Collection Demonstrates Maturation of Elimination Clearance. Anesth Analg 2024; 138:447-455. [PMID: 38215717 PMCID: PMC10794030 DOI: 10.1213/ane.0000000000006808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2024]
Abstract
BACKGROUND Fentanyl is widely used for analgesia and sedation in neonates, but pharmacokinetic (PK) analysis in this population has been limited by the relatively large sample volumes required for plasma-based assays. METHODS In this multicenter observational study of fentanyl kinetics in neonates up to 42 weeks of postmenstrual age (PMA) who received fentanyl boluses and continuous infusions, dried blood spots were used for small-volume sampling. A population PK analysis was used to describe fentanyl disposition in term and preterm neonates. Covariates for the model parameters, including body weight, PMA, birth status (preterm or term), and presence of congenital cardiac disease, were assessed in a stepwise manner. RESULTS Clearance was estimated to be greater than adult clearance of fentanyl and varied with weight. Covariate selection did not yield a significant relationship for age as a continuous or dichotomous variable (term or preterm, the latter defined as birth with PMA of <37 weeks) and clearance. CONCLUSIONS A supra-allometric effect on clearance was determined during covariate analyses (exponential scaling factor for body weight >0.75), as has been described in population PK models that account for maturation of intrinsic clearance (here, predominantly hepatic microsomal activity) in addition to scaling for weight, both of which impact clearance in this age group.
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Affiliation(s)
- Rachael S Rzasa Lynn
- From the Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado
| | - Thomas K Henthorn
- From the Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado
| | - Jeannie Zuk
- From the Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado
| | - Gregory B Hammer
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Palo Alto, California
| | - David R Drover
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Palo Alto, California
| | - Richard J Levy
- Department of Anesthesiology, Columbia University Medical Center, New York, New York
| | - Lynne G Maxwell
- Department of Anesthesiology and Critical Care Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Senthilkumar Sadhasivam
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Santhanam Suresh
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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3
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Okada CR, Henthorn TK, Zuk J, Sempio C, Roosevelt G, Ruiz AG, Cohen MN, Chatterjee D, Galinkin JL. Population Pharmacokinetics of Single Bolus Dose Fentanyl in Obese Children. Anesth Analg 2024; 138:99-107. [PMID: 37801572 PMCID: PMC10840858 DOI: 10.1213/ane.0000000000006554] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/08/2023]
Abstract
BACKGROUND Childhood obesity is a significant problem. Obesity may alter the pharmacokinetics (PKs) of medications. Fentanyl is commonly used for procedural sedation, but there is a paucity of bolus dose fentanyl PK data in obese children. Better understanding of fentanyl PK in obese children would facilitate dosing recommendations. We conducted a study involving children with and without obesity to assess the potential differences in bolus dose fentanyl PK between the 2 groups. METHODS We enrolled children 2 to 12 years of age with and without obesity, defined as >95th percentile body mass index (BMI) for age and sex, undergoing elective tonsillectomy ± adenoidectomy. After induction, subjects had 2 intravenous (IV) lines placed in 2 different extremities: 1 for medications and IV fluids and 1 for obtaining blood aliquots for fentanyl concentration analysis. After administration of 1 mcg/kg of fentanyl based on total body weight (TBW), blood sample collections for fentanyl concentration analysis were attempted at 5, 15, 30, 60, 90, and 120 minutes. Five-minute fentanyl concentrations were compared between obese and nonobese cohorts. Population PK analysis to examine the differences between obese and nonobese children was performed and included various body size descriptors, such as TBW, BMI, and fat-free mass (FFM), to examine their influence on model parameters. RESULTS Half of the 30 subjects were obese. Mean fentanyl concentrations at 5 minutes were 0.53 ng/mL for the nonobese group and 0.88 ng/mL for the obese group, difference 0.35 ng/mL (95% CI, 0.08-0.61 ng/mL; P = .01). Population PK analysis showed that FFM was a significant covariate for the central volume of distribution. The potential clinical effect of an IV bolus dose of fentanyl based on TBW versus FFM in an obese child was assessed in a simulation using our model. 1 mcg/kg fentanyl dose based on TBW resulted in an approximately 60% higher peak fentanyl effect site concentration than dosing based on FFM. CONCLUSIONS Our data demonstrated higher peak plasma fentanyl concentrations in obese compared to nonobese subjects. Population PK analysis found that FFM was a significant covariate for the central volume of distribution. Model simulation showed dosing of fentanyl in obese children based on TBW resulted in significantly higher peak concentrations than dosing based on FFM. Based on this modeling and the known concentration-effect relationship between fentanyl and adverse effects, our results suggest that bolus dosing of fentanyl in obese children should be based on FFM rather than TBW, particularly for procedures of short duration.
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Affiliation(s)
- Carol R Okada
- From the Division of Pediatric Critical Care, University of Colorado School of Medicine, Aurora, Colorado
| | - Thomas K Henthorn
- Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado
| | - Jeannie Zuk
- University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Cristina Sempio
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Genie Roosevelt
- Department of Emergency Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Amanda G Ruiz
- New York Medical College School of Medicine, Tarrytown, New York
| | - Mindy N Cohen
- New York Medical College School of Medicine, Tarrytown, New York
| | - Debnath Chatterjee
- Department of Anesthesiology, Children's Hospital Colorado/University of Colorado Anschutz Medical Campus, Aurora, Colorado
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4
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Vellinga R, Eleveld DJ, Struys MMRF, van den Berg JP. General purpose models for intravenous anesthetics, the next generation for target-controlled infusion and total intravenous anesthesia? Curr Opin Anaesthesiol 2023; 36:602-607. [PMID: 37678184 DOI: 10.1097/aco.0000000000001300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
PURPOSE OF REVIEW There are various pharmacokinetic-dynamic models available, which describe the time course of drug concentration and effect and which can be incorporated into target-controlled infusion (TCI) systems. For anesthesia and sedation, most of these models are derived from narrow patient populations, which restricts applicability for the overall population, including (small) children, elderly, and obese patients. This forces clinicians to select specific models for specific populations. RECENT FINDINGS Recently, general purpose models have been developed for propofol and remifentanil using data from multiple studies and broad, diverse patient groups. General-purpose models might reduce the risks associated with extrapolation, incorrect usage, and unfamiliarity with a specific TCI-model, as they offer less restrictive boundaries (i.e., the patient "doesn't fit in the selected model") compared with the earlier, simpler models. Extrapolation of a model can lead to delayed recovery or inadequate anesthesia. If multiple models for the same drug are implemented in the pump, it is possible to select the wrong model for that specific case; this can be overcome with one general purpose model implemented in the pump. SUMMARY This article examines the usability of these general-purpose models in relation to the more traditional models.
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Affiliation(s)
- Remco Vellinga
- Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Douglas J Eleveld
- Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Michel M R F Struys
- Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Johannes P van den Berg
- Department of Anesthesiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Egan TD, Johnson KB. Editorial: Advances in perioperative clinical pharmacology: giant leaps and small steps. Curr Opin Anaesthesiol 2023; 36:390-393. [PMID: 37431246 DOI: 10.1097/aco.0000000000001283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Affiliation(s)
- Talmage D Egan
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, USA
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6
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Abstract
A clinical review is presented of basic allometric scaling theory and its application to pharmacokinetic models in anesthesia and other fields in the biologic sciences.
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7
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van Rongen A, Krekels EH, Calvier EA, de Wildt SN, Vermeulen A, Knibbe CA. An update on the use of allometric and other scaling methods to scale drug clearance in children: towards decision tables. Expert Opin Drug Metab Toxicol 2022; 18:99-113. [PMID: 35018879 DOI: 10.1080/17425255.2021.2027907] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION When pediatric data are not available for a drug, allometric and other methods are applied to scale drug clearance across the pediatric age-range from adult values. This is applied when designing first-in-child studies, but also for off-label drug prescription. AREAS COVERED This review provides an overview of the systematic accuracy of allometric and other pediatric clearance scaling methods compared to gold-standard PBPK predictions. The findings are summarized in decision tables to provide a priori guidance on the selection of appropriate pediatric clearance scaling methods for both novel drugs for which no pediatric data are available and existing drugs in clinical practice. EXPERT OPINION While allometric scaling principles are commonly used to scale pediatric clearance, there is no universal allometric exponent (i.e., 1, 0.75 or 0.67) that can accurately scale clearance for all drugs from adults to children of all ages. Therefore, pediatric scaling decision tables based on age, drug elimination route, binding plasma protein, fraction unbound, extraction ratio, and/or isoenzyme maturation are proposed to a priori select the appropriate (allometric) clearance scaling method, thereby reducing the need for full PBPK-based clearance predictions. Guidance on allometric scaling when estimating pediatric clearance values is provided as well.
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Affiliation(s)
- Anne van Rongen
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Elke Hj Krekels
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Elisa Am Calvier
- Sanofi Pharmacokinetics-Dynamics and Metabolism (PKDM), Translational Medicine and Early Development, Sanofi R&D, Montpellier, France
| | - Saskia N de Wildt
- Department of Pharmacology and Toxicology, Radboud University Medical Center, Nijmegen, The Netherlands.,Intensive Care and Department of Pediatric Surgery, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands
| | - An Vermeulen
- Laboratory of Medical Biochemistry and Clinical Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium.,Janssen R&D, a division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Catherijne Aj Knibbe
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands.,Department of Clinical Pharmacy, St. Antonius Hospital, Nieuwegein, The Netherlands
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8
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Damian MA, Hammer GB, Elkomy MH, Frymoyer A, Drover DR, Su F. Pharmacokinetics of Dexmedetomidine in Infants and Children After Orthotopic Liver Transplantation. Anesth Analg 2020; 130:209-216. [PMID: 30198929 DOI: 10.1213/ane.0000000000003761] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Dexmedetomidine (DEX) is a sedative and analgesic medication that is frequently used postoperatively in children after liver transplantation. Hepatic dysfunction, including alterations in drug clearance, is common immediately after liver transplantation. However, the pharmacokinetics (PK) of DEX in this population is unknown. The objective of this study was to determine the PK profile of DEX in children after liver transplantation. METHODS This was a single-center, open-label PK study of DEX administered as an intravenous loading dose of 0.5 μg/kg followed by a continuous infusion of 0.5 μg/kg/h. Twenty subjects, 1 month to 18 years of age, who were admitted to the pediatric intensive care unit after liver transplantation were enrolled. Whole blood was collected and analyzed for DEX concentration using a dried blood spot method. Nonlinear mixed-effects modeling was used to characterize the population PK of DEX. RESULTS DEX PK was best described by a 2-compartment model with first-order elimination. A typical child after liver transplantation with an international normalized ratio (INR) of 1.8 was found to have a whole blood DEX clearance of 52 L/h (95% confidence interval [CI], 31-73 L/h). In addition, intercompartmental clearance was 246 L/h (95% CI, 139-391 L/h), central volume of distribution was 186 L/70 kg (95% CI, 140-301 L/70 kg), and peripheral volume of distribution was 203 L (95% CI, 123-338 L). Interindividual variability ranged from 11% to 111% for all parameters. Clearance was not found to be associated with weight but was found to be inversely proportional to INR. An increase in INR to 3.2 resulted in a 50% decrease in DEX clearance. Weight was linearly correlated with central volume of distribution. All other covariates, including age, ischemic time, total bilirubin, and alanine aminotransferase, were not found to be significant predictors of DEX disposition. CONCLUSIONS Children who received DEX after liver transplantation have large variability in clearance, which was not found to be associated with weight but is influenced by underlying liver function, as reflected by INR. In this population, titration of DEX dosing to clinical effect may be important because weight-based dosing is poorly associated with blood concentrations. More attention to quality of DEX sedation may be warranted when INR values are changing.
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Affiliation(s)
- Mihaela A Damian
- From the Department of Pediatrics, Pediatric Critical Care Medicine
| | - Gregory B Hammer
- From the Department of Pediatrics, Pediatric Critical Care Medicine.,Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California
| | - Mohammed H Elkomy
- Department of Pharmaceutics, Jouf University, Sakaka, Saudi Arabia.,Department of Pharmaceutics and Industrial Pharmacy, Beni-Suef University, Beni-Suef, Egypt
| | - Adam Frymoyer
- From the Department of Pediatrics, Pediatric Critical Care Medicine
| | - David R Drover
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Stanford, California
| | - Felice Su
- From the Department of Pediatrics, Pediatric Critical Care Medicine
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9
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Sinha J, Al-Sallami HS, Duffull SB. Choosing the Allometric Exponent in Covariate Model Building. Clin Pharmacokinet 2020; 58:89-100. [PMID: 29704107 DOI: 10.1007/s40262-018-0667-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
BACKGROUND Allometric scaling is often used to describe the covariate model linking total body weight (WT) to clearance (CL); however, there is no consensus on how to select its value. OBJECTIVES The aims of this study were to assess the influence of between-subject variability (BSV) and study design on (1) the power to correctly select the exponent from a priori choices, and (2) the power to obtain unbiased exponent estimates. METHODS The influence of WT distribution range (randomly sampled from the Third National Health and Nutrition Examination Survey, 1988-1994 [NHANES III] database), sample size (N = 10, 20, 50, 100, 200, 500, 1000 subjects), and BSV on CL (low 20%, normal 40%, high 60%) were assessed using stochastic simulation estimation. A priori exponent values used for the simulations were 0.67, 0.75, and 1, respectively. RESULTS For normal to high BSV drugs, it is almost impossible to correctly select the exponent from an a priori set of exponents, i.e. 1 vs. 0.75, 1 vs. 0.67, or 0.75 vs. 0.67 in regular studies involving < 200 adult participants. On the other hand, such regular study designs are sufficient to appropriately estimate the exponent. However, regular studies with < 100 patients risk potential bias in estimating the exponent. CONCLUSION Those study designs with limited sample size and narrow range of WT (e.g. < 100 adult participants) potentially risk either selection of a false value or yielding a biased estimate of the allometric exponent; however, such bias is only relevant in cases of extrapolating the value of CL outside the studied population, e.g. analysis of a study of adults that is used to extrapolate to children.
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Affiliation(s)
- Jaydeep Sinha
- School of Pharmacy, University of Otago, PO Box 56, Dunedin, 9054, New Zealand.
| | - Hesham S Al-Sallami
- School of Pharmacy, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Stephen B Duffull
- School of Pharmacy, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
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10
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Abstract
In covariate (sub)models of population pharmacokinetic models, most covariates are normalized to the median value; however, for body weight, normalization to 70 kg or 1 kg is often applied. In this article, we illustrate the impact of normalization weight on the precision of population clearance (CLpop) parameter estimates. The influence of normalization weight (70, 1 kg or median weight) on the precision of the CLpop estimate, expressed as relative standard error (RSE), was illustrated using data from a pharmacokinetic study in neonates with a median weight of 2.7 kg. In addition, a simulation study was performed to show the impact of normalization to 70 kg in pharmacokinetic studies with paediatric or obese patients. The RSE of the CLpop parameter estimate in the neonatal dataset was lowest with normalization to median weight (8.1%), compared with normalization to 1 kg (10.5%) or 70 kg (48.8%). Typical clearance (CL) predictions were independent of the normalization weight used. Simulations showed that the increase in RSE of the CLpop estimate with 70 kg normalization was highest in studies with a narrow weight range and a geometric mean weight away from 70 kg. When, instead of normalizing with median weight, a weight outside the observed range is used, the RSE of the CLpop estimate will be inflated, and should therefore not be used for model selection. Instead, established mathematical principles can be used to calculate the RSE of the typical CL (CLTV) at a relevant weight to evaluate the precision of CL predictions.
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11
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Pérez-Guillé MG, Toledo-López A, Rivera-Espinosa L, Alemon-Medina R, Murata C, Lares-Asseff I, Chávez-Pacheco JL, Gómez-Garduño J, Zamora Gutiérrez AL, Orozco-Galicia C, Ramírez-Morales K, Lugo-Goytia G. Population Pharmacokinetics and Pharmacodynamics of Dexmedetomidine in Children Undergoing Ambulatory Surgery. Anesth Analg 2019; 127:716-723. [PMID: 29782406 PMCID: PMC6110617 DOI: 10.1213/ane.0000000000003413] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Dexmedetomidine (DEX) is an α-2 adrenergic agonist with sedative and analgesic properties. Although not approved for pediatric use by the Food and Drug Administration, DEX is increasingly used in pediatric anesthesia and critical care. However, very limited information is available regarding the pharmacokinetics of DEX in children. The aim of this study was to investigate DEX pharmacokinetics and pharmacodynamics (PK-PD) in Mexican children 2-18 years of age who were undergoing outpatient surgical procedures. METHODS Thirty children 2-18 years of age with American Society of Anesthesiologists physical status score of I/II were enrolled in this study. DEX (0.7 μg/kg) was administered as a single-dose intravenous infusion. Venous blood samples were collected, and plasma DEX concentrations were analyzed with a combination of high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry. Population PK-PD models were constructed using the Monolix program. RESULTS A 2-compartment model adequately described the concentration-time relationship. The parameters were standardized for a body weight of 70 kg by using an allometric model. Population parameters estimates were as follows: mean (between-subject variability): clearance (Cl) (L/h × 70 kg) = 20.8 (27%); central volume of distribution (V1) (L × 70 kg) = 21.9 (20%); peripheral volume of distribution (V2) (L × 70 kg) = 81.2 (21%); and intercompartmental clearance (Q) (L/h × 70 kg) = 75.8 (25%). The PK-PD model predicted a maximum mean arterial blood pressure reduction of 45% with an IC50 of 0.501 ng/ml, and a maximum heart rate reduction of 28.9% with an IC50 of 0.552 ng/ml. CONCLUSIONS Our results suggest that in Mexican children 2-18 years of age with American Society of Anesthesiologists score of I/II, the DEX dose should be adjusted in accordance with lower DEX clearance.
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Affiliation(s)
| | | | | | | | - Chiharu Murata
- Departamento de Metodología de la Investigación, Instituto Nacional de Pediatría, México
| | | | | | | | | | | | | | - Gustavo Lugo-Goytia
- Departamento de Anestesiología y Medicina Crítica, Instituto Nacional de Ciencias Médicas y Nutrición, México
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12
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Brooks Peterson M, Cohen MN, O'Neill BR, Garg S, Child J, Henthorn TK, Galinkin JG. Preoperative Vancomycin Administration for Surgical Site Prophylaxis: Plasma and Soft-Tissue Concentrations in Pediatric Neurosurgical and Orthopedic Patients. Anesth Analg 2019; 130:1435-1444. [PMID: 31397701 DOI: 10.1213/ane.0000000000004340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Vancomycin is used for antibiotic prophylaxis in pediatric surgical patients without a complete understanding of plasma and soft-tissue pharmacokinetics. Guidelines recommend incision within 60 minutes after administration; however, tissue vancomycin concentrations at that early time may not be therapeutic. We conducted a study of plasma and skin concentrations in pediatric neurosurgical and orthopedic patients to characterize intraoperative vancomycin pharmacokinetics. METHODS Patients (0.1-18.8 years of age) undergoing posterior spinal fusion (n = 30) or ventriculoperitoneal shunt placement (n = 30) received intravenous vancomycin 15 mg/kg (maximum 1000 mg) over 1 hour. Skin was biopsied at incision and skin closure. Blood samples were collected at incision, at 2 and 4 hours intraoperatively, and at closure. Population pharmacokinetic analysis was performed to characterize pharmacokinetic parameter estimates and to develop a model of intraoperative plasma and skin vancomycin concentrations versus time. RESULTS Pharmacokinetic analysis included data from 59 subjects, 130 plasma samples, and 107 skin samples. A 2-compartment model, volume of the central (Vc) and volume of the peripheral compartment (V2), proved to have the best fit. Stepwise covariate selection yielded a significant relationship for body surface area on elimination clearance and body weight on V2. Skin vancomycin concentrations rose continuously during surgery. Modeling predicted that equilibration of skin and plasma vancomycin concentrations took ≥5 hours. CONCLUSIONS Skin vancomycin concentrations immediately after a preoperative dose are relatively low compared with concentrations at the end of surgery. It may be advisable to extend the time between dose and incision if higher skin concentrations are desired at the start of surgery.
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Affiliation(s)
| | | | | | - Sumeet Garg
- Department of Orthopedic Surgery, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, Colorado
| | - Jason Child
- Department of Pharmacy, Children's Hospital Colorado, Aurora, Colorado
| | - Thomas K Henthorn
- Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado
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13
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Krekels EHJ, Calvier EAM, van der Graaf PH, Knibbe CAJ. Children Are Not Small Adults, but Can We Treat Them As Such? CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2019; 8:34-38. [PMID: 30689298 PMCID: PMC6363065 DOI: 10.1002/psp4.12366] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/18/2018] [Indexed: 02/04/2023]
Abstract
Although children cannot be considered small adults due to nonlinear processes underlying the pharmacokinetics of drugs, pediatric doses are typically still expressed per kilogram. We use a physiologically based pharmacokinetic (PBPK) workflow to assess the accuracy of linear scaling of plasma clearance (CLp) for hypothetical drugs with ranges of realistic parameter values in pediatric patients of different ages. The results are compared with 0.75 fixed allometric scaling (AS 0.75). Linear CLp scaling is accurate down to the age of 1 month for drugs undergoing glomerular filtration, except when these drugs are highly bound to alpha‐1‐acid glycoprotein (AGP). For hepatically cleared drugs, linear scaling is reasonably accurate down the age of 2 years, except for AGP‐bound drugs with a low extraction ratio and mature isoenzymes. In neonates, linear scaling outperforms AS 0.75 for human serum albumin (HSA) and AGP‐bound drugs excreted through glomerular filtration. These results suggest that pediatric patients can, in many cases, be treated as small adults.
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Affiliation(s)
- Elke H J Krekels
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Center of Drug Research, Leiden University, Leiden, The Netherlands
| | - Elisa A M Calvier
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Center of Drug Research, Leiden University, Leiden, The Netherlands
| | - Piet H van der Graaf
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Center of Drug Research, Leiden University, Leiden, The Netherlands.,Certara QSP, Canterbury, UK
| | - Catherijne A J Knibbe
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Center of Drug Research, Leiden University, Leiden, The Netherlands.,Department of Clinical Pharmacy, St. Antonius Hospital, Nieuwegein, The Netherlands
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Target-Controlled Infusion: Not a One-Sized-Fits-All Answer to Drug Administration. Anesth Analg 2018; 127:813-814. [PMID: 30216283 DOI: 10.1213/ane.0000000000003461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Advances in pharmacokinetic modeling: target controlled infusions in the obese. Curr Opin Anaesthesiol 2018; 31:415-422. [PMID: 29794852 DOI: 10.1097/aco.0000000000000619] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
PURPOSE OF REVIEW The use of conventional pharmacokinetic parameters sets 'models' derived from nonobese patients has proven inadequate to administer intravenous anesthetics in the obese population and is commonly associated with higher than anticipated plasma propofol concentrations when used with target (plasma or effect site) controlled infusion pumps. In this review we will describe recent modeling strategies to characterize the disposition of intravenous anesthetics in the obese patient and will show clinically relevant aspects of new model's performance in the obese population. RECENT FINDINGS Because clearance of a drug increases in a nonlinear manner with weight, nonlinear relationships better scale infusion rates between lean and obese individuals. Allometric concepts have been successfully used to describe size-related nonlinear changes in clearances. Other nonlinear scaling options include the use of descriptors such as body surface area, lean body weight, fat-free mass, and normal fat mass. Newer pharmacokinetic models, determined from obese patient data, have been developed for propofol and remifentanil using allometric concepts and comprehensive size descriptors. SUMMARY Pharmacokinetic models to perform target-controlled infusion in the obese population should incorporate descriptors that reflect with greater precision the influence of body composition in volumes and clearances of each drug. It is our hope that commercially available pumps will soon incorporate these new models to improve the performance of this technique in the obese population.
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Eleveld DJ, Colin P, Absalom AR, Struys MMRF. Pharmacokinetic-pharmacodynamic model for propofol for broad application in anaesthesia and sedation. Br J Anaesth 2018; 120:942-959. [PMID: 29661412 DOI: 10.1016/j.bja.2018.01.018] [Citation(s) in RCA: 129] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/11/2018] [Accepted: 01/22/2018] [Indexed: 10/17/2022] Open
Abstract
BACKGROUND Pharmacokinetic (PK) and pharmacodynamic (PD) models are used in target-controlled-infusion (TCI) systems to determine the optimal drug administration to achieve a desired target concentration in a central or effect-site compartment. Our aim was to develop a PK-PD model for propofol that can predict the bispectral index (BIS) for a broad population, suitable for TCI applications. METHODS Propofol PK data were obtained from 30 previously published studies, five of which also contained BIS observations. A PK-PD model was developed using NONMEM. Weight, age, post-menstrual age (PMA), height, sex, BMI, and presence/absence of concomitant anaesthetic drugs were explored as covariates. The predictive performance was measured across young children, children, adults, elderly, and high-BMI individuals, and in simulated TCI applications. RESULTS Overall, 15 433 propofol concentration and 28 639 BIS observations from 1033 individuals (672 males and 361 females) were analysed. The age range was from 27 weeks PMA to 88 yr, and the weight range was 0.68-160 kg. The final model uses age, PMA, weight, height, sex, and presence/absence of concomitant anaesthetic drugs as covariates. A 35-yr-old, 170 cm, 70 kg male (without concomitant anaesthetic drugs) has a V1, V2, V3, CL, Q2, Q3, and ke0 of 6.28, 25.5, 273 litres, 1.79, 1.75, 1.11 litres min-1, and 0.146 min-1, respectively. The propofol TCI administration using the model matches well with recommendations for all age groups considered for both anaesthesia and sedation. CONCLUSIONS We developed a PK-PD model to predict the propofol concentrations and BIS for broad, diverse population. This should be useful for TCI in anaesthesia and sedation.
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Affiliation(s)
- D J Eleveld
- Department of Anesthesiology, University Medical Center Groningen, Groningen, The Netherlands.
| | - P Colin
- Department of Anesthesiology, University Medical Center Groningen, Groningen, The Netherlands; Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - A R Absalom
- Department of Anesthesiology, University Medical Center Groningen, Groningen, The Netherlands
| | - M M R F Struys
- Department of Anesthesiology, University Medical Center Groningen, Groningen, The Netherlands; Department of Anesthesia and Peri-operative Medicine, Ghent University, Ghent, Belgium
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Cortínez LI, Sepúlveda P, Rolle A, Cottin P, Guerrini A, Anderson BJ. Effect-Site Target-Controlled Infusion in the Obese: Model Derivation and Performance Assessment. Anesth Analg 2018; 127:865-872. [PMID: 29401079 DOI: 10.1213/ane.0000000000002814] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND The aim of this study is to derive a propofol pharmacokinetic (PK) pharmacodynamic (PD) model to perform effect-site target-controlled infusion (TCI) in obese patients, and to analyze its performance along with that of other available PK models. METHODS In the first step of the study, a 3-compartment PK model linked to a sigmoidal inhibitory Emax PD model by a first-order rate constant (keo) was used to fit propofol concentration-bispectral index (BIS) data. Population modeling analysis was performed by nonlinear mixed effects regression in NONMEM (ICON, Dublin, Ireland). PK data from 3 previous studies in obese adult patients (n = 47), including PD (BIS) data from 1 of these studies (n = 20), were pooled and simultaneously analyzed. A decrease in NONMEM objective function (ΔOBJ) of 3.84 points, for an added parameter, was considered significant at the 0.05 level. In the second step of the study, we analyzed the predictive performance (median predictive errors [MDPE] and median absolute predictive errors [MDAPE]) of the current model and of other available models using an independent data set (n = 14). RESULTS Step 1: The selected PKPD model produced an adequate fit of the data. Total body weight resulted in the best size scalar for volumes and clearances (ΔOBJ, -18.173). Empirical allometric total body weight relationships did not improve model fit (ΔOBJ, 0.309). A lag time parameter for BIS response improved the fit (ΔOBJ, 89.593). No effect of age or gender was observed. Step 2: Current model MDPE and MDAPE were 11.5% (3.7-25.0) and 26.8% (20.7-32.6) in the PK part and 0.4% (-10.39 to 3.85) and 11.9% (20.7-32.6) in the PD part. The PK model developed by Eleveld et al resulted in the lowest PK predictive errors (MDPE = <10% and MDAPE = <25%). CONCLUSIONS We derived and validated a propofol PKPD model to perform effect-site TCI in obese patients. This model, derived exclusively from obese patient's data, is not recommended for TCI in lean patients because it carries the risk of underdosing.
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Affiliation(s)
- Luis I Cortínez
- From the Department of Anaesthesiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Pablo Sepúlveda
- Servicio de Anestesia, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Augusto Rolle
- From the Department of Anaesthesiology, Pontificia Universidad Católica de Chile, Santiago, Chile
| | | | | | - Brian J Anderson
- Department of Anaesthesiology, University of Auckland, Auckland, New Zealand
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Abstract
Abstract
Background
The influence of obesity on the pharmacokinetic (PK) behavior of remifentanil is incompletely understood. The aim of the current investigation was to develop a new population PK model for remifentanil that would adequately characterize the influence of body weight (among other covariates, e.g., age) on the disposition of remifentanil in the general adult population. We hypothesized that age and various indices of body mass would be important covariates in the new model.
Methods
Nine previously published data sets containing 4,455 blood concentration measurements from 229 subjects were merged. A new PK model was built using nonlinear mixed-effects modeling. Satisfactory model performance was assessed graphically and numerically; an internal, boot-strapping validation procedure was performed to determine the CIs of the model.
Results
Body weight, fat-free body mass, and age (but not body mass index) exhibited significant covariate effects on certain three-compartment model parameters. Visual and numerical assessments of model performance were satisfactory. The bootstrap procedure showed satisfactory CIs on all of the model parameters.
Conclusions
A new model estimated from a large, diverse data set provides the PK foundation for remifentanil dosing calculations in adult obese and elderly patients. It is suitable for use in target-controlled infusion systems and pharmacologic simulation.
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Mahmood I, Tegenge MA. Population Pharmacokinetics: Some Observations in Pediatric Modeling for Drug Clearance. Clin Pharmacokinet 2017; 56:1567-1576. [PMID: 28405936 DOI: 10.1007/s40262-017-0542-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The objective of this study is to evaluate the predictive performance of several models to predict drug clearance in preterm and term neonates. Five models using different types of allometric and linear models were developed. Two sets of data were used to develop these models (data from preterm neonates to adults and data from preterm and term neonates). Models were also developed with (normalized to 70 kg) or without body weight normalization (body weight 1 kg). From the literature, clearance values for four drugs from neonates to adults were obtained. External data were used to evaluate the predictive performance of these models in preterm and term neonates. The results of the study indicated that (1) normalization to a standard body weight had no impact on the predictive performance of the models, (2) the model developed from preterm neonates to adults using fixed exponent 0.75 provided inaccurate estimate (overestimation) of drug clearance in neonates, (3) a far superior prediction of clearance was observed with the model when the exponents of allometry were estimated than the model using exponent 0.75, (4) linear models with the exception of the model with intercept provided comparable results to the estimated exponent model and were superior in their predictive performance to the model using exponent 0.75, and (5) when the models were developed from neonate data, the predictive performance of all models were similar. Overall, the study indicated that body weight normalization had no impact on the performance of model prediction, the exponents of allometry in pharmacostatistical models should be estimated rather than fixed, and more studies are needed to evaluate the suitability of linear models for the prediction of drug clearance in neonates.
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Affiliation(s)
- Iftekhar Mahmood
- Office of Tissue and Advance Therapeutics, Center for Biologics Evaluation and Research, US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD, 20993-0002, USA.
| | - Million A Tegenge
- Office of Biostatistics and Epidemiology, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD, USA
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