Publications by authors named "Pierre Chelle"

16 Publications

  • Page 1 of 1

Use of population PK/PD approach to model the thrombin generation assay: assessment in haemophilia A plasma samples spiked by a TFPI antibody.

J Pharmacokinet Pharmacodyn 2021 Apr 12. Epub 2021 Apr 12.

School of Pharmacy, University of Waterloo, Kitchener, ON, Canada.

The thrombin generation (TG) assay is a well-established tool to capture the clotting potential of any healthy or haemophiliac subject. It measures ex vivo the kinetics of thrombin activation throughout the coagulation. Clinical studies allowed to create two databases gathering the coagulation factor levels and the thrombin generation profile of 40 healthy and 40 haemophiliac A (HA) subjects. Besides, portions of all HA samples were spiked with increasing levels of a TFPI antibody (considered as a possible therapeutic target) and corresponding TG profiles were determined. The non-linear mixed-effect (NLME) modelling aims at describing and explaining the experimentally observed important variability of the TG curves between subjects and the individual effects of spiking with a TFPI antibody. The models consist of an empirical description of the TG kinetics, accounting for an additive residual error and between-subject variability on its parameters. Factor VIII and TFPI were found to significantly explain and reduce the variability of the TG of haemophilia A samples. Besides, the model is shown to correctly reproduce the variability in the response to the ex vivo spiking with the TFPI antibody, by combining the empirical description of TG to a simple Hill equation that accounts for the binding between TFPI and different doses of its antibody. Such models can be useful for clinical practice, with the analysis and comparison of the distributions of TG profiles in healthy and haemophilia populations; and also for research, with the analysis of the effect of TFPI and its neutralization on individual TG profiles.
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http://dx.doi.org/10.1007/s10928-021-09752-1DOI Listing
April 2021

Limited sampling strategies for accurate determination of extended half-life factor VIII pharmacokinetics in severe haemophilia A patients.

Haemophilia 2021 Mar 20. Epub 2021 Mar 20.

Department of Pharmaceutical Sciences, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.

Background: Extended half-life (EHL) factor VIII (FVIII) products may decrease the burden of prophylactic treatment in haemophilia A by reducing infusion frequency. However, these products still exhibit wide inter-patient variability and benefit from pharmacokinetic (PK) tailoring.

Objective: Identify limited sampling strategies for rFVIIIFc, an EHL FVIII product, that produce accurate estimates of PK parameters and relevant troughs.

Methods: We performed a limited sampling analysis on simulated populations of adults, adolescents, and children based on published population PK data. Sampling strategies were evaluated by comparing the error in estimates of half-life, clearance, and trough levels, to a full 6-sample design. Furthermore, we assessed the impact of incorporating knowledge about prior doses, and the day of the PK study within the regimen. We also evaluated the potential inappropriate dose adjustment rate (IDAR) among the modelled sampling strategies.

Results: Many sampling strategies, including several 2-sample designs, accurately predicted the PK and exposure measures (median absolute error <10%). When samples are only collected during a single visit (i.e., predose + peak), inclusion of prior dose information reduces median half-life error from >20% to ~5% for adults/adolescents. In this same scenario, appropriate scheduling of the PK study decreases likelihood of unmeasurable predose samples, reducing median error on the 72-h trough from 25% to <12% in the youngest population.

Conclusions: The PK of rFVIIIFc can be accurately estimated using only peak and trough samples, provided that knowledge of prior doses is incorporated and the PK study is planned on an appropriate day within the dosing regimen.
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http://dx.doi.org/10.1111/hae.14288DOI Listing
March 2021

Pharmacokinetic implications of dosing emicizumab based on vial size: A simulation study.

Haemophilia 2021 Mar 2. Epub 2021 Mar 2.

School of Pharmacy, University of Waterloo, Waterloo, ON, Canada.

Introduction: Emicizumab is dosed as mg/kg and, according to the label, any unused drug left in the vial(s) must be discarded, thereby wasting expensive resources. The aim of this study was to use population pharmacokinetics to illustrate the implications of changing the dosing interval to avoid wastage.

Methods: We used a previously published emicizumab PopPK model after extending its validation to children. We simulated PK parameters for labelled dosing regimens and for regimens using full vials with infusion frequency varied to keep the steady-state drug concentration unchanged. Cost and drug savings were calculated.

Results: The model evaluation was successful. When rounding up, the average individual below 53, 47 and 39 has a time-to-trough increase of up to 5.7, 7.9 and 5.8 days for the QW, Q2 W and Q4 W regimen, respectively. This resulted in an annual cost reduction of up to $173,136, $75,747 and $61,319 USD per patient. At higher body weights, rounding down the dose to the nearest vial resulted in negligible changes in the steady state concentration and cost savings of up to $93,781, $46,891 and $23,446 USD per patient, respectively.

Conclusion: Individuals with a lower body weight may benefit from increasing dose intervals and rounding up dose up to the nearest vial, and individuals with a higher body weight from maintaining the injection frequency and rounding dose down to the nearest vial without significant change in emicizumab levels. Administering the entire vial may result in a reduction of vials used annually and potential cost savings.
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http://dx.doi.org/10.1111/hae.14292DOI Listing
March 2021

Development and evaluation of the population pharmacokinetic models for FVIII and FIX concentrates of the WAPPS-Hemo project.

Haemophilia 2020 May 13;26(3):384-400. Epub 2020 Apr 13.

School of Pharmacy, University of Waterloo, Waterloo, ON, Canada.

Background: The Web-Accessible Population Pharmacokinetic Service (WAPPS) project generates individually predicted pharmacokinetic (PK) profiles and tailored prophylactic treatment regimens for haemophilic patients, which rely on a set of population PK (PopPK) models providing concentrate-specific priors for the Bayesian forecasting methodology.

Aim: To describe the predictive performance of the WAPPS PopPK models in use on the WAPPS-Hemo platform.

Methods: Data for modelling include dense PK data obtained from industry sponsored and independent PK studies, and dense and sparse data accumulated through WAPPS-Hemo. WAPPS PopPK models were developed via non-linear mixed-effect modelling taking into account the effects of covariates and between-individual-and sometimes between-occasion-variability. Model evaluation consisted of (a) prediction-corrected Visual Predictive Check (pcVPC), (b) Limited Sampling Analysis (LSA) and (c) repeated hold-out cross-validation.

Results: Thirty-three WAPPS PopPK models built on data from 3188 patients (ages 1-78 years) under treatment by factor VIII or IX products (FVIII, FIX) were evaluated. Overall, models exhibit excellent performance characteristics. The pcVPC shows that the observed PK data fall within acceptable 90% interpercentile predictive bands. A slight overprediction beyond the expected half-life, an anticipated result of using sparse data, occurs for some models. The LSA results in lower than 3% of relative error for FVIII and FIX products and 16% for engineered FIX products. Cross-Validation analysis yields relative errors lower than 1.5% and 1.4% in estimates of half-life and time to 0.02 IU/mL, respectively.

Conclusion: The WAPPS-Hemo models consistently showed excellent performance characteristics for the intended use for Bayesian forecasting of individual PK profiles.
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http://dx.doi.org/10.1111/hae.13977DOI Listing
May 2020

Multicentre pharmacokinetic evaluation of rFVIII-Fc (efmoroctocog alfa) in a real life and comparison with non-extended half-life FVIII concentrates.

Haemophilia 2020 Mar 27;26(2):282-289. Epub 2020 Feb 27.

Laboratoire d'Hémostase Hémobiologie, CHU de Lille, Lille, France.

The use of enhanced half-life (EHL) FVIII has improved the quality of prophylaxis in haemophilia A, but with a benefit that may vary from one patient to another. We analysed the pharmacokinetic data obtained with efmoroctocog alfa (rFVIII-Fc) in 114 patients and, in 47 cases, compared them to those previously measured with non-EHL FVIII. The in vivo recovery (IVR) of rFVIII-Fc measured with one stage clotting assay (OSA) and chromogenic assay (CSA) was 2.2 and 2.8 IU/mL per IU/kg, respectively. The median half-life (T ) of rFVIII-Fc was 14.5 hours whatever the FVIII:C assay used, but variable and correlated with preinfusion VWF:Ag levels (r = .76). Both IVR and T were lower in patients under 12 years old (2.4 IU/mL per IU/kg and 11.1 hours, respectively; CSA). PK study of rFVIII-Fc vs non-EHL FVIII showed a T ratio of 1.4 in favour of rFVIII-Fc, regardless of the patient's age. However the relative increase in T with rFVIII-Fc was lower than 30% in one-third of patients evaluated, particularly when the previous FVIII administered was a BHK-derived product. This study therefore suggests that analysis of individual PK profile in response to a specific FVIII concentrate is potentially useful before a switch in haemophilia A patients.
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http://dx.doi.org/10.1111/hae.13946DOI Listing
March 2020

A comparison of methods for prediction of pharmacokinetics across factor concentrate switching in hemophilia patients.

Thromb Res 2019 Dec 29;184:31-37. Epub 2019 Oct 29.

School of Pharmacy, University of Waterloo, Waterloo, Ontario, Canada. Electronic address:

Introduction: This study proposes a method to predict individual pharmacokinetics of a future product by using the individual pharmacokinetic profile on the current product and the PopPK models of the current and future product.

Methods: Individual dense data was collected from two PK crossover studies, one enrolling 29 patients switching from Advate to Eloctate and one enrolling 15 patients switching from Advate to Novoeight. Three methods were designed to predict the second product's individual PK parameters (CL, V1, Q, and V2). Method 1 used the second product's typical population value of PK parameters from its PopPK model. Method 2 used the second product's calculated PK parameters based on individual covariates and its PopPK model. Method 3 used method 2, along with the predicted η-values of CL and V1 from the first product and its PopPK model. Each method was used to assess PK prediction during switching from Advate to Novoeight, Novoeight to Advate, and Advate to Eloctate.

Results: The three methods produced different outcomes. The mean absolute relative errors for half-life were lowest for method 3 for each study (11.6%, 13.1%, 13.6%). The regression line between predicted and observed half-life for method 3 was closest to the line of identity for each study (0.84, 0.67, 0.66).

Conclusion: Taking into account individual PK from a previous clotting factor product was shown to provide better means of estimating individual PK for a new product. This may improve regimen design across switches and reduce the time to tailor optimal dose of FVIII products.
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http://dx.doi.org/10.1016/j.thromres.2019.10.023DOI Listing
December 2019

Development and Validation of a Population-Pharmacokinetic Model for Rurioctacog Alfa Pegol (Adynovate): A Report on Behalf of the WAPPS-Hemo Investigators Ad Hoc Subgroup.

Clin Pharmacokinet 2020 02;59(2):245-256

Department of Health Research Methods, Evidence, and Impact, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4K1, Canada.

Background And Objective: Rurioctacog alfa pegol (Adynovate) is a modified recombinant factor VIII concentrate used for treating hemophilia A. Aiming to improve treatment tailoring on the Web-Accessible Population Pharmacokinetic Service-Hemophilia (WAPPS-Hemo) platform for patients of all ages treated with Adynovate, we have developed and evaluated a population pharmacokinetic (PopPK) model. On the platform, PopPK models are used as priors for Bayesian forecasting that derive individual PK of hemophilia patients and are subsequently used for personalized dose regimen design.

Methods: Factor activity measurements and demographic covariate data from patients infused with Adynovate were extracted from the WAPPS-Hemo database. Evaluations testing the appropriateness of Bayesian forecasting included 10-fold cross validation, a limited sampling analysis (LSA), and an external evaluation using additional independent data extracted from the WAPPS-Hemo database at a later date.

Results: The model was constructed using 650 plasma factor activity observations (555 one stage assay and 95 chromogenic assay - 4.6% below limit of quantification) measured in 154 patients from 36 hemophilia centres. A two-compartment model including between subject variability on clearance and central volume was selected as the base model. Covariates were fat free mass on clearance and central volume, age on clearance and assay type on activity. The final model was well-suited to predict PK parameters of new individuals (n = 26) from sparse observations.

Conclusions: The development of a PopPK model for Adynovate using real-world data increases the covariate space (e.g. age) beyond what is possible from clinical trial data. This model is available on the WAPPS-Hemo platform for tailoring treatment in hemophilia A patients.
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http://dx.doi.org/10.1007/s40262-019-00809-6DOI Listing
February 2020

Correction to: Routine clinical care data for population pharmacokinetic modeling: the case for Fanhdi/Alphanate in hemophilia A patients.

J Pharmacokinet Pharmacodyn 2019 Oct;46(5):439

School of Pharmacy, University of Waterloo, Waterloo, ON, Canada.

The article Routine clinical care data for population pharmacokinetic modeling: the case for Fanhdi/Alphanate in hemophilia A patients, written by Pierre Chelle, Cindy H. T. Yeung, Santiago Bonanad, Juan Cristóbal Morales Muñoz, Margareth C. Ozelo, Juan Eduardo Megías Vericat, Alfonso Iorio, Jeffrey Spears, Roser Mir, Andrea Edginton, was originally published electronically on the publisher's internet portal (currently SpringerLink) on 21 May 2019 without open access.
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http://dx.doi.org/10.1007/s10928-019-09647-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6820592PMC
October 2019

Routine clinical care data for population pharmacokinetic modeling: the case for Fanhdi/Alphanate in hemophilia A patients.

J Pharmacokinet Pharmacodyn 2019 10 21;46(5):427-438. Epub 2019 May 21.

School of Pharmacy, University of Waterloo, Waterloo, ON, Canada.

Fanhdi/Alphanate is a plasma derived factor VIII concentrate used for treating hemophilia A, for which there has not been any dedicated model describing its pharmacokinetics (PK). A population PK model was developed using data extracted from the Web-Accessible Population Pharmacokinetic Service-Hemophilia (WAPPS-Hemo) project. WAPPS-Hemo provided individual PK profiles for hemophilia patients using sparse observations as provided in routine clinical care by hemophilia centers. Plasma factor activity measurements and covariate data from hemophilia A patients on Fanhdi/Alphanate were extracted from the WAPPS-Hemo database. A population PK model was developed using NONMEM and evaluated for suitability for Bayesian forecasting using prediction-corrected visual predictive check (pcVPC), cross validation, limited sampling analysis and external evaluation against a population PK model developed on rich sampling data. Plasma factor activity measurements from 92 patients from 12 centers were used to derive the model. The PK was best described by a 2-compartment model including between subject variability on clearance and central volume, fat free mass as a covariate on clearance, central and peripheral volumes, and age as covariate on clearance. Evaluations showed that the developed population PK model could predict the PK parameters of new individuals based on limited sampling analysis and cross and external evaluations with acceptable precision and bias. This study shows the feasibility of using real-world data for the development of a population PK model. Evaluation and comparison of the model for Bayesian forecasting resulted in similar results as a model developed using rich sampling data.
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http://dx.doi.org/10.1007/s10928-019-09637-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6820598PMC
October 2019

Development and evaluation of a generic population pharmacokinetic model for standard half-life factor VIII for use in dose individualization.

J Pharmacokinet Pharmacodyn 2019 Oct 18;46(5):411-426. Epub 2019 May 18.

School of Pharmacy, University of Waterloo, Waterloo, ON, Canada.

Hemophilia A is a rare bleeding disorder resulting from a lack of functional factor VIII (FVIII). Therapy consists of replacement with exogenous FVIII, but is complicated by high inter-patient variability. A population pharmacokinetics (PopPK) approach can facilitate the uptake of an individualized approach to hemophilia therapy. We developed a PopPK model using data from seven brands of standard half-life FVIII products. The final model consists of a 2-compartment structure, with a proportional residual error model and between-subject variability on clearance and central volume. Fat-free mass, age, and brand were found to significantly affect pharmacokinetic (PK) parameters. Internal and external evaluations found that the model is fit for Bayesian forecasting and capable of predicting PK for brands not included in the modelling dataset, and useful for determining individualized prophylaxis regimens for hemophilia A patients.
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http://dx.doi.org/10.1007/s10928-019-09634-7DOI Listing
October 2019

Comparative pharmacokinetics of two extended half-life FVIII concentrates (Eloctate and Adynovate) in adolescents with hemophilia A: Is there a difference?

J Thromb Haemost 2019 07 2;17(7):1085-1096. Epub 2019 Jun 2.

Division of Haematology/Oncology, Department of Paediatrics and Child Health Evaluative Sciences, Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.

Essentials The PK parameters of Eloctate vs Adynovate were compared using one-stage and chromogenic assays in 25 boys (12-18 years). The FVIII levels were taken at 3, 24, 48, and 72 hours following a dose of either FVIII; levels analyzed by WAPPS PK program. The PK profiles (half-life, clearance, and time to 5%, 3%, and 1%) were not statistically different for the two EHL FVIIIs. The significant interpatient variability in PK is mainly related to VWF levels (and blood group).

Background: A head-to-head comparison of the pharmokinetcs (PK) of extended half-life (EHL) factor VIII (FVIII) concentrates in the same subjects has not been reported. Recently, boys (ages 12-18 years) with hemophilia A in Canada were required to switch from Eloctate to Adynovate.

Objectives: Compare the PK profiles of Eloctate vs Adynovate in the same boys.

Methods: Boys switching from Eloctate to Adynovate prophylaxis had FVIII levels sampled at 3, 24, 48, and 72 hours following a regular prophylactic infusion of Eloctate and then 1-3 months later, of Adynovate. Testing was done by one-stage assay (OSA) and chromogenic assay (CA). The PK parameters were determined with the Web Accessible Population Pharmacokinetic Service (WAPPS)-Hemo PK tool.

Results: Twenty-five boys (mean age 15.3 years; range: 12.1-18.4; 9 O blood group) underwent switching. Mean (range) terminal half-lives with the OSA were 16.1 hours (10.4 to 23.4; Eloctate) and 16.7 hours (11.0 to 23.6; Adynovate) (NS). With the CA, these were 18.0 hours (12.0 to 25.5; Eloctate) and 16.0 hours (10.3 to 22.9; Adynovate) (P = 0.001). There were no significant differences between the two EHL-FVIIIs in clearance, area under the concentration vs time curve (AUC), Vss, or time for FVIII levels to drop to 5%, 3%, and 1%. At the 72-h time point, mean observed FVIII levels following a mean dose of 39.3 IU/kg of Eloctate were 4.4% (OSA) and 4.4% (CA). For Adynovate, these were 5.1% (OSA) and 5.3% (CA) following similar doses. There was considerable interpatient variation in PK, mainly explained by differences in blood group/von Willebrand factor (VWF) levels.

Conclusions: Eloctate and Adynovate have almost identical PK parameters. When switching from one to another no prophylaxis regimen change is needed.
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http://dx.doi.org/10.1111/jth.14469DOI Listing
July 2019

Biodistribution and Physiologically-Based Pharmacokinetic Modeling of Gold Nanoparticles in Mice with Interspecies Extrapolation.

Pharmaceutics 2019 Apr 12;11(4). Epub 2019 Apr 12.

School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada.

Gold nanoparticles (AuNPs) are a focus of growing medical research applications due to their unique chemical, electrical and optical properties. Because of uncertain toxicity, "green" synthesis methods are emerging, using plant extracts to improve biological and environmental compatibility. Here we explore the biodistribution of green AuNPs in mice and prepare a physiologically-based pharmacokinetic (PBPK) model to guide interspecies extrapolation. Monodisperse AuNPs were synthesized and capped with epigallocatechin gallate (EGCG) and curcumin. 64 CD-1 mice received the AuNPs by intraperitoneal injection. To assess biodistribution, groups of six mice were sacrificed at 1, 7, 14, 28 and 56 days, and their organs were analyzed for gold content using inductively coupled plasma mass spectrometry (ICP-MS). A physiologically-based pharmacokinetic (PBPK) model was developed to describe the biodistribution data in mice. To assess the potential for interspecies extrapolation, organism-specific parameters in the model were adapted to represent rats, and the rat PBPK model was subsequently evaluated with PK data for citrate-capped AuNPs from literature. The liver and spleen displayed strong uptake, and the PBPK model suggested that extravasation and phagocytosis were key drivers. Organ predictions following interspecies extrapolation were successful for rats receiving citrate-capped AuNPs. This work lays the foundation for the pre-clinical extrapolation of the pharmacokinetics of AuNPs from mice to larger species.
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http://dx.doi.org/10.3390/pharmaceutics11040179DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6523871PMC
April 2019

Tissue factor pathway inhibitor is the main determinant of thrombin generation in haemophilic patients.

Haemophilia 2019 Mar 28;25(2):343-348. Epub 2019 Jan 28.

INSERM, U1059, SAINBIOSE, Université de Lyon, UJM-Saint-Etienne, Saint-Etienne, France.

The thrombin generation (TG) assay evaluates haemostatic balance, which is influenced by the levels of many coagulation factors and inhibitors. Our objective was to identify the determinant factors of TG in haemophilia A (HA) and haemophilia B (HB) patients and to compare them to those in healthy controls. Coagulation factor and inhibitor levels, and TG, were measured in platelet-poor plasma from 40 patients with HA, 32 patients with HB and 40 healthy subjects. Data were analysed using multiple regression models. In HA patients, factor VIII was a positive determinant of endogenous thrombin potential (ETP) and peak, whereas tissue factor pathway inhibitor (TFPI) and factor V were negative determinants of ETP and peak. In HB patients, FIX was a positive determinant of ETP and peak, FVII being a positive determinant of peak. Antithrombin and protein S (PS) were negative determinants of ETP while FX was a negative determinant of peak. Above all, in HB patients, TFPI was a negative determinant of ETP and peak. In healthy subjects, FVIII was a positive determinant of ETP and peak, whereas FX and protein S were negative determinants of these parameters. TFPI was not a negative determinant of either peak or ETP. In haemophilic patients, the determinant factors of TG are all implicated in FXa generation and inhibition, the crucial determinant factor being TFPI whatever the type of haemophilia, A or B. These findings contribute to the rationale that recently place TFPI as a target for innovative therapies of haemophilia.
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http://dx.doi.org/10.1111/hae.13679DOI Listing
March 2019

Evaluation and Calibration of In Silico Models of Thrombin Generation Using Experimental Data from Healthy and Haemophilic Subjects.

Bull Math Biol 2018 08 13;80(8):1989-2025. Epub 2018 Jun 13.

INSERM, U1059, SAINBIOSE, F-42000, Saint Etienne, Univ Lyon, Univ Jean Monnet, INSERM, 42023, Saint-Étienne, France.

The coagulation cascade comprises numerous chemical reactions between many proteins, that finally lead to the formation of a clot to stop bleeding. Many numerical models have attempted to translate understanding of this cascade into mathematical equations that simulate the chain reactions. However, their predictions have not been validated against clinical data stemming from patients. In this paper, we propose an extensive validation of five available models, by comparing in healthy and haemophilic subjects, thrombin generation measured in vitro to thrombin generation predicted by the models in silico. In order to render the models more predictive, we calibrated the models to have an acceptable agreement between the experimental and estimated data. Optimization processes based on genetic algorithms were developed to search for those calibrated kinetic parameters. Our results show that the thrombin generation kinetics are so complex that they cannot be predicted by a unique set of kinetic parameters for all patients: the calibration of only three parameters in a subject-specific way allows reaching good model estimations for different experimental conditions realized on the same patient.
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http://dx.doi.org/10.1007/s11538-018-0440-4DOI Listing
August 2018

A method for the quantitative extraction of gold nanoparticles from human bronchoalveolar lavage fluids through a glycerol gradient.

Nanoscale 2018 Feb;10(6):2955-2969

Université de Lyon, Faculté de Médecine, INSERM U1059 SAINBIOSE, F-42270 Saint-Etienne, France.

Bronchoalveolar lavage (BAL) is a diagnostic procedure which samples the cellular and non-cellular components of the pulmonary epithelial surface. The inherent biological noise of BAL fluids inhibits their direct mineralogical analysis while currently available particle retrieval protocols are suspected to impose quantitative and qualitative bias on the studied particle load. This study presents a simple method for the near-lossless extraction of citrate-capped gold nanoparticles from human BAL fluids at sub-ppm levels which enables their quantitation and surface characterization. This procedure was modeled according to fundamental principles of particle sedimentation and liquid-liquid interdiffusion and was evaluated by a battery of analytical techniques. The extraction yield of gold nanoparticles ranged from 61 to 86%, with a quantitation limit at 0.5 μg ml, as measured by inductively-coupled optical emission spectroscopy. Dynamic light scattering could resolve the hydrodynamic size distribution of extracted particles which returned significantly different photon count rates at various concentrations. Their shape and primary size were easily observable by electron microscopy while atomic force microscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy could respectively probe the particles' biomolecular corona, detect surface-adsorbed S- and N- species, and identify carbon-based covalent bonds.
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http://dx.doi.org/10.1039/c7nr04484dDOI Listing
February 2018

Modeling of Body Weight Metrics for Effective and Cost-Efficient Conventional Factor VIII Dosing in Hemophilia A Prophylaxis.

Pharmaceutics 2017 Oct 17;9(4). Epub 2017 Oct 17.

School of Pharmacy, University of Waterloo, Waterloo, ON N2L 3G1, Canada.

The total body weight-based dosing strategy currently used in the prophylactic treatment of hemophilia A may not be appropriate for all populations. The assumptions that guide weight-based dosing are not valid in overweight and obese populations, resulting in overdosing and ineffective resource utilization. We explored different weight metrics including lean body weight, ideal body weight, and adjusted body weight to determine an alternative dosing strategy that is both safe and resource-efficient in normal and overweight/obese adult patients. Using a validated population pharmacokinetic model, we simulated a variety of dosing regimens using different doses, weight metrics, and frequencies; we also investigated the implications of assuming various levels of endogenous factor production. Ideal body weight performed the best across all of the regimens explored, maintaining safety while moderating resource consumption for overweight and obese patients.
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http://dx.doi.org/10.3390/pharmaceutics9040047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5750653PMC
October 2017