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El Hassani M, Liebchen U, Marsot A. Does Sample Size, Sampling Strategy, or Handling of Concentrations Below the Lower Limit of Quantification Matter When Externally Evaluating Population Pharmacokinetic Models? Eur J Drug Metab Pharmacokinet 2024; 49:419-436. [PMID: 38705941 DOI: 10.1007/s13318-024-00897-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2024] [Indexed: 05/07/2024]
Abstract
BACKGROUND AND OBJECTIVES Precision dosing requires selecting the appropriate population pharmacokinetic model, which can be assessed through external evaluations (EEs). The lack of understanding of how different study design factors influence EE study outcomes makes it challenging to select the most suitable model for clinical use. This study aimed to evaluate the impact of sample size, sampling strategy, and handling of concentrations below the lower limit of quantification (BLQ) on the outcomes of EE for four population pharmacokinetic models using vancomycin and tobramycin as examples. METHODS Three virtual patient populations undergoing vancomycin or tobramycin therapy were simulated with varying sample size and sampling scenarios. The three approaches used to handle BLQ data were to (1) discard them, (2) impute them as LLOQ/2, or (3) use a likelihood-based approach. EEs were performed with NONMEM and R. RESULTS Sample size did not have an important impact on the EE results for a given scenario. Increasing the number of samples per patient did not improve predictive performance for two out of the three evaluated models. Evaluating a model developed with rich sampling did not result in better performance than those developed with regular therapeutic drug monitoring. A likelihood-based method to handle BLQ samples impacted the outcomes of the EE with lower bias for predicted troughs. CONCLUSIONS This study suggests that a large sample size may not be necessary for an EE study, and models selected based on TDM may be more generalizable. The study highlights the need for guidelines for EE of population pharmacokinetic models for clinical use.
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Affiliation(s)
- Mehdi El Hassani
- Faculté de pharmacie, Université de Montréal, 2940 chemin de Polytechnique, Montréal, QC, H3T 1J4, Canada.
- Laboratoire de suivi thérapeutique pharmacologique et pharmacocinétique, Faculté de pharmacie, Université de Montréal, Montreal, QC, Canada.
| | - Uwe Liebchen
- Department of Anaesthesiology, LMU University Hospital, LMU Munich, 81377, Munich, Germany
| | - Amélie Marsot
- Faculté de pharmacie, Université de Montréal, 2940 chemin de Polytechnique, Montréal, QC, H3T 1J4, Canada
- Laboratoire de suivi thérapeutique pharmacologique et pharmacocinétique, Faculté de pharmacie, Université de Montréal, Montreal, QC, Canada
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Schlegtendal A, Rettberg S, Maier C, Brinkmann F, Koerner-Rettberg C. Necessity of Tobramycin trough Levels in Once Daily Iv-Treatment in Patients with Cystic Fibrosis. KLINISCHE PADIATRIE 2024; 236:116-122. [PMID: 38286409 DOI: 10.1055/a-2244-6903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
BACKGROUND Once daily intravenous (iv) treatment with tobramycin for Pseudomonas aeruginosa infection in patients with cystic fibrosis (pwCF) is frequently monitored by measuring tobramycin trough levels (TLs). Although the necessity of these TLs is recently questioned in pwCF without renal impairment, no study has evaluated this so far. The aim of this observational study was to evaluate the frequency of increased tobramycin TLs in pwCF treated with a once daily tobramycin dosing protocol. METHODS Patient records of all consecutive once daily iv tobramycin courses in 35 pwCF between 07/2009 and 07/2019 were analyzed for tobramycin level, renal function, co-medication and comorbidity. RESULTS Eight elevated TLs (2.9% of 278 courses) were recorded in four patients, two with normal renal function. One of these resolved without adjustment of tobramycin dosages suggesting a test timing or laboratory error. In the other patient the elevated tobramycin level decreased after tobramycin dosage adjustment. Six of the elevated levels occurred in two patients with chronic renal failure. In 15 other patients with reduced glomerular filtration rate (GFR) (36 courses) but normal range creatinine no case of elevated tobramycin trough levels was detected. Neither cumulative tobramycin dosages nor concomitant diabetes or nutritional status were risk factors for elevated TLs. CONCLUSION Our data show that elevated tobramycin TLs are rare but cannot be excluded, so determination of tobramycin TLs is still recommended for safety.
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Affiliation(s)
- Anne Schlegtendal
- Department of pediatrics, Ruhr-Universität Bochum Medizinische Fakultät, Bochum, Germany
| | - Sophia Rettberg
- Department of pediatrics, Ruhr-Universität Bochum Medizinische Fakultät, Bochum, Germany
| | - Christoph Maier
- Department of pediatrics, Ruhr-Universität Bochum Medizinische Fakultät, Bochum, Germany
| | - Folke Brinkmann
- Department of pediatrics, Ruhr-Universität Bochum Medizinische Fakultät, Bochum, Germany
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El Hassani M, Thirion DJG, Koloskoff K, Matouk E, Simard C, Cloutier I, Pilote S, Marsot A. Development and Evaluation of a Height-Based Tobramycin Initial Dosing Nomogram for the Treatment of Adult Cystic Fibrosis Pulmonary Exacerbations. Ther Drug Monit 2023; 45:259-264. [PMID: 36730982 DOI: 10.1097/ftd.0000000000001053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 10/03/2022] [Indexed: 02/04/2023]
Abstract
ABSTRACT Tobramycin is widely used to treat pulmonary exacerbations of cystic fibrosis. Height has been previously found to be significantly more predictive of tobramycin pharmacokinetics than body weight. This study aimed to develop a height-based initial dosing nomogram and evaluate its performance in peak concentration (Cmax) precision relative to standard and fixed dosing. Monte Carlo simulations were performed to develop a nomogram representing the doses required to reach Cmax targets at different heights. Cmax data observed at 2 clinical centers [McGill University Health Centre (MUHC) and Institut universitaire de cardiologie et pneumologie de Québec (IUCPQ-UL)] were compared with population-predicted Cmax using the doses derived from the nomogram alongside a fixed dose. Height-based dosing resulted in significantly less variable-predicted Cmax values [coefficient of variation (CV) MUHC = 15.7% and IUCPQ-UL = 10.8%] than the Cmax values observed in clinical practice (CV MUHC = 30.0% and CV IUCPQ-UL = 26.9%) and predicted Cmax values obtained from a fixed dose (CV MUHC = 21.2% and CV IUCPQ-UL = 16.3%). An initial dosing nomogram was developed to help reduce pharmacokinetic variability in the observed Cmax. More precise dosing would allow for better clinical outcomes in adult patients with cystic fibrosis.
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Affiliation(s)
- Mehdi El Hassani
- Faculté de pharmacie, Université de Montréal, Montreal, Canada
- Laboratoire de suivi thérapeutique pharmacologique et pharmacocinétique, Faculté de pharmacie, Université de Montréal, Montreal, Canada
| | - Daniel J G Thirion
- Faculté de pharmacie, Université de Montréal, Montreal, Canada
- Department of Pharmacy, McGill University Health Centre, Montreal, Canada
| | - Kevin Koloskoff
- Faculté de pharmacie, Université de Montréal, Montreal, Canada
- Laboratoire de suivi thérapeutique pharmacologique et pharmacocinétique, Faculté de pharmacie, Université de Montréal, Montreal, Canada
| | - Elias Matouk
- Adult Cystic Fibrosis Clinic, Montreal Chest Institute, McGill University, Montreal, Canada
- Department of Medicine, McGill University, Montreal, Canada
- McGill University Health Center Research Institute, Montreal, Canada
| | - Chantale Simard
- Faculté de pharmacie, Université Laval, Quebec, Canada
- Centre de recherche, Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Quebec, Canada; and
| | - Isabelle Cloutier
- Faculté de pharmacie, Université Laval, Quebec, Canada
- Département de pharmacie, Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Quebec, Canada
| | - Sylvie Pilote
- Faculté de pharmacie, Université Laval, Quebec, Canada
| | - Amélie Marsot
- Faculté de pharmacie, Université de Montréal, Montreal, Canada
- Laboratoire de suivi thérapeutique pharmacologique et pharmacocinétique, Faculté de pharmacie, Université de Montréal, Montreal, Canada
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Koloskoff K, Thirion DJG, Matouk E, Marsot A. New Recommendations of a Height-Based Dosing Regimen of Tobramycin for Cystic Fibrosis in Adults: A Population Pharmacokinetic Analysis. Ther Drug Monit 2023; 45:251-258. [PMID: 36070759 DOI: 10.1097/ftd.0000000000001021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 07/08/2022] [Indexed: 11/26/2022]
Abstract
BACKGROUND Acute pulmonary exacerbations (APEs) in patients with adult cystic fibrosis (CF) are treated with a beta-lactam and an aminoglycoside for activity against Pseudomonas aeruginosa (PA). Emerging drug resistance and changing pharmacokinetic profile in an aging population involve a reevaluation of tobramycin dosing recommendations. The objective of this study was to develop a population pharmacokinetic model and establish optimal dosing recommendations for tobramycin using Monte Carlo simulations. METHODS This retrospective clinical study and data collection were performed at the CF center of the McGill University Health Center (MUHC), Canada. Model development and simulations were performed using a nonlinear mixed-effect modeling approach (NONMEM, version 7.4.2). The ratios of maximal concentration (C max ) to the minimal inhibitory concentration (MIC) (C max /MIC ≥8 and ≥10) and area under the curve (AUC) to the MIC (AUC/MIC ≥70 and ≥100) were evaluated. RESULTS Adult patients with CF (n = 51) treated with tobramycin were included in the study. Plasma concentrations of tobramycin were obtained for 699 samples from the MUHC database. The two-compartmental model best described the pharmacokinetics of tobramycin. The association of patient height with the central volume of distribution significantly improved this model. Height, rather than weight, induced the best reduction in objective function. According to simulations, doses between 3.4 mg/cm and 4.4 mg/cm were necessary to achieve C max /MIC values of ≥8 and ≥10, respectively. However, higher doses were required to achieve the AUC/MIC targets. CONCLUSIONS This study demonstrated that height of the patients seems to be more suitable than their weight for dosing adjustments in adult patients with CF. According to this model, initial doses of tobramycin between 3.4 and 4.4 mg/cm should be recommended for patients with a median height of 164 cm and weight of 55 kg to achieve the target plasma concentrations.
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Affiliation(s)
- Kevin Koloskoff
- Faculty of Pharmacy, Université de Montréal
- Laboratoire STP2, Faculty of Pharmacy, Université de Montréal; and
| | - Daniel J G Thirion
- Faculty of Pharmacy, Université de Montréal
- Pharmacy Department, Royal Victoria Hospital, McGill University Health Centre
| | - Elias Matouk
- Adult Cystic Fibrosis Clinic, Montreal Chest Institute, McGill University, Montreal, Quebec, Canada
| | - Amélie Marsot
- Faculty of Pharmacy, Université de Montréal
- Laboratoire STP2, Faculty of Pharmacy, Université de Montréal; and
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El Hassani M, Simard C, Pilote S, Cloutier I, Soufsaf S, Marsot A. Consideration of height-based tobramycin dosing regimens for the treatment of adult cystic fibrosis pulmonary exacerbations. Br J Clin Pharmacol 2021; 88:2246-2255. [PMID: 34820875 DOI: 10.1111/bcp.15154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 11/10/2021] [Accepted: 11/12/2021] [Indexed: 11/30/2022] Open
Abstract
AIMS Some population pharmacokinetic models have been developed using height to explain some of the interindividual variability in tobramycin pharmacokinetics in cystic fibrosis patients. However, their predictive performance when extrapolated to other clinical centres is unclear. Therefore, the aim of this study was to externally evaluate the predictability of tobramycin population pharmacokinetic models with an independent dataset and perform simulations using previously recommended height-based dosing regimens. METHODS A literature search was conducted through the PubMed database to identify relevant population pharmacokinetic models. Tobramycin plasma concentration data from April 2014 to November 2019 were retrospectively collected from the Institut universitaire de cardiologie et de pneumologie de Québec, Canada. External evaluations were performed using NONMEM® v7.5 and RStudio® v1.3.1073. Monte Carlo simulations were performed to evaluate the probability of target attainment of Cmax /MIC ratios for several dosing regimens. RESULTS The validation dataset included 27 patients and 143 concentration samples. Three models were evaluated. Only the ones by Crass et al. and Alghanem et al. performed satisfactorily in terms of prediction-based diagnostics with MDPE values of -3.4% and 29.3% and MDAPE values of 19.0 and 29.5%, respectively. In simulation-based evaluations, both pcVPC and NPDE showed no evidence of model misspecification. Our simulations suggest that patients treated with a once-daily dose of 3.4 mg/cm should produce peak and trough levels consistent with current guidelines. CONCLUSION Our results show that the models by Crass et al. and Alghanem et al. are appropriate for simulation-based applications to aid individualized dosing in our population and that height-based dosing regimens could be considered in cystic fibrosis patients.
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Affiliation(s)
- Mehdi El Hassani
- Faculté de pharmacie, Université de Montréal, Canada.,Laboratoire de suivi thérapeutique pharmacologique et pharmacocinétique, Faculté de pharmacie, Université de Montréal, Canada
| | - Chantale Simard
- Faculté de pharmacie, Université Laval, Canada.,Centre de recherche, Institut universitaire de cardiologie et de pneumologie de Québec, Canada
| | - Sylvie Pilote
- Centre de recherche, Institut universitaire de cardiologie et de pneumologie de Québec, Canada
| | - Isabelle Cloutier
- Faculté de pharmacie, Université Laval, Canada.,Département de pharmacie, Institut universitaire de cardiologie et de pneumologie de Québec, Canada
| | - Sara Soufsaf
- Faculté de pharmacie, Université de Montréal, Canada
| | - Amélie Marsot
- Faculté de pharmacie, Université de Montréal, Canada.,Laboratoire de suivi thérapeutique pharmacologique et pharmacocinétique, Faculté de pharmacie, Université de Montréal, Canada
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Population pharmacokinetic modeling and dosing simulations of tobramycin in pediatric patients with cystic fibrosis. Antimicrob Agents Chemother 2021; 65:e0073721. [PMID: 34280011 DOI: 10.1128/aac.00737-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Initial dosing and dose adjustment of intravenous tobramycin in cystic fibrosis children is challenging. The objectives of this study were to develop nonparametric population pharmacokinetic (PK) models of tobramycin in children with CF to be used for dosage design and model-guided therapeutic drug monitoring. We performed a retrospective analysis of tobramycin PK data in our CF children center. The Pmetrics package was used for nonparametric population PK analysis and dosing simulations. Both the maximal concentration over the MIC (Cmax/MIC) and daily area under the concentration-time curve to the MIC (AUC24/MIC) ratios were considered as efficacy target. Trough concentration (Cmin) was considered as the safety target. A total of 2884 tobramycin concentrations collected in 195 patients over 9 years were analyzed. A two-compartment model including total body weight, body surface area and creatinine clearance as covariates best described the data. A simpler model was also derived for implementation into the BestDose software to perform Bayesian dose adjustment. Both models were externally validated. PK/PD simulations with the final model suggest that an initial dose of tobramycin of 15 to 17.5 mg/kg/day was necessary to achieve Cmax/MIC ≥ 10 values for MIC values up to 2 mg/L in most patients. The AUC24/MIC target was associated with larger dosage requirements and higher Cmin. A daily dose of 12.5 mg/kg would optimize both efficacy and safety target attainment. We recommend to perform tobramycin TDM, model-based dose adjustment, and MIC determination to individualize intravenous tobramycin therapy in children with CF.
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Duong A, Simard C, Wang YL, Williamson D, Marsot A. Aminoglycosides in the Intensive Care Unit: What Is New in Population PK Modeling? Antibiotics (Basel) 2021; 10:antibiotics10050507. [PMID: 33946905 PMCID: PMC8145041 DOI: 10.3390/antibiotics10050507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 11/16/2022] Open
Abstract
Background: Although aminoglycosides are often used as treatment for Gram-negative infections, optimal dosing regimens remain unclear, especially in ICU patients. This is due to a large between- and within-subject variability in the aminoglycoside pharmacokinetics in this population. Objective: This review provides comprehensive data on the pharmacokinetics of aminoglycosides in patients hospitalized in the ICU by summarizing all published PopPK models in ICU patients for amikacin, gentamicin, and tobramycin. The objective was to determine the presence of a consensus on the structural model used, significant covariates included, and therapeutic targets considered during dosing regimen simulations. Method: A literature search was conducted in the Medline/PubMed database, using the terms: ‘amikacin’, ‘gentamicin’, ‘tobramycin’, ‘pharmacokinetic(s)’, ‘nonlinear mixed effect’, ‘population’, ‘intensive care’, and ‘critically ill’. Results: Nineteen articles were retained where amikacin, gentamicin, and tobramycin pharmacokinetics were described in six, 11, and five models, respectively. A two-compartment model was used to describe amikacin and tobramycin pharmacokinetics, whereas a one-compartment model majorly described gentamicin pharmacokinetics. The most recurrent significant covariates were renal clearance and bodyweight. Across all aminoglycosides, mean interindividual variability in clearance and volume of distribution were 41.6% and 22.0%, respectively. A common consensus for an optimal dosing regimen for each aminoglycoside was not reached. Conclusions: This review showed models developed for amikacin, from 2015 until now, and for gentamicin and tobramycin from the past decades. Despite the growing challenges of external evaluation, the latter should be more considered during model development. Further research including new covariates, additional simulated dosing regimens, and external validation should be considered to better understand aminoglycoside pharmacokinetics in ICU patients.
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Affiliation(s)
- Alexandre Duong
- Faculté de Pharmacie, Université de Montréal, Montréal, QC H3T 1J4, Canada; (Y.L.W.); (D.W.); (A.M.)
- Laboratoire de Suivi Thérapeutique Pharmacologique et Pharmacocinétique, Faculté de Pharmacie, Université de Montréal, Montréal, QC H3T 1J4, Canada
- Correspondence: ; Tel.: +1-514-343-6111
| | - Chantale Simard
- Faculté de Pharmacie, Université Laval, Québec, QC G1V 0A6, Canada;
- Centre de Recherche, Institut Universitaire de Cardiologie et Pneumologie de Québec, Québec, QC G1V 4G5, Canada
| | - Yi Le Wang
- Faculté de Pharmacie, Université de Montréal, Montréal, QC H3T 1J4, Canada; (Y.L.W.); (D.W.); (A.M.)
- Laboratoire de Suivi Thérapeutique Pharmacologique et Pharmacocinétique, Faculté de Pharmacie, Université de Montréal, Montréal, QC H3T 1J4, Canada
| | - David Williamson
- Faculté de Pharmacie, Université de Montréal, Montréal, QC H3T 1J4, Canada; (Y.L.W.); (D.W.); (A.M.)
- Hôpital Sacré-Cœur de Montréal, Montréal, QC H4J 1C5, Canada
| | - Amélie Marsot
- Faculté de Pharmacie, Université de Montréal, Montréal, QC H3T 1J4, Canada; (Y.L.W.); (D.W.); (A.M.)
- Laboratoire de Suivi Thérapeutique Pharmacologique et Pharmacocinétique, Faculté de Pharmacie, Université de Montréal, Montréal, QC H3T 1J4, Canada
- Centre de Recherche, CHU Sainte Justine, Montréal, QC H3T 1C5, Canada
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De Sutter PJ, Gasthuys E, Van Braeckel E, Schelstraete P, Van Biervliet S, Van Bocxlaer J, Vermeulen A. Pharmacokinetics in Patients with Cystic Fibrosis: A Systematic Review of Data Published Between 1999 and 2019. Clin Pharmacokinet 2020; 59:1551-1573. [DOI: 10.1007/s40262-020-00932-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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