References of "Lebrun, Pierre"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailApplication of a new optimization strategy for the separation of tertiary alkaloids extracted from Strychnos usambarensis leaves
Nistor, Iolanda ULg; Cao, Martine ULg; Debrus, Benjamin ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2011), 56

The HPLC separation of six alkaloids extracted from Strychnos usambarensis leaves has been developed and optimized by means of a powerful methodology for modelling chromatographic responses, based on ... [more ▼]

The HPLC separation of six alkaloids extracted from Strychnos usambarensis leaves has been developed and optimized by means of a powerful methodology for modelling chromatographic responses, based on three steps, i.e. design of experiments (DoE), independent component analysis (ICA) and design space (DS). This study was the first application of a new optimization strategy to a complex natural matrix. The compounds separated are the isomers isostrychnopentamine and strychnopentamine, 10-hydroxyusambarine and 11-hydroxyusambarine, also strychnophylline and strychnofoline. Three LC parameters have been optimized using a multifactorial design comprising 29 experiments that includes 2 center point replicates. The parameters were the percentage of organic modifiers used at the beginning of a gradient profile which consisted in different proportions of methanol (MeOH) and acetonitrile (MeCN), the gradient time to reach 70% of organic modifiers starting from the initial percentage and the percentage of MeCN found in the mobile phase. Subsequent to the experimental design application, predictive multilinear models were developed and used in order to provide optimal analytical conditions. The optimum assay conditions were: methanol/acetonitrile-sodium pentane sulfonate (pH 2.2; 7.5 mM) (33.4:66.6, v/v) at a mobile phase flow rate of 1mL/min during a 40.6 minutes gradient time. The initial organic phase contained 3.7% MeCN and 96.3% MeOH. The method showed good agreement between the experimental data and predictive value throughout the studied parameters space. Improvement of the analysis time and optimized separation for the compounds of interest was possible due to the original and powerful tools applied. Finally, this study permitted the acquisition of isomers profiles allowing the identification of the optimal collecting period of Strychnos usambarensis. [less ▲]

Detailed reference viewed: 84 (48 ULg)
Full Text
Peer Reviewed
See detailDetermination of binary polymorphic mixtures of fluconazole using near infrared spectroscopy and X-ray powder diffraction: A comparative study based on the pre-validation stage results
Ziemons, Eric ULg; Bourichi, H.; Mantanus, Jérôme ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2011), 55

The aim of the present study was to develop near infrared (NIR) and X-ray powder diffraction methods (XRPD) able to determine pure crystalline form II of fluconazole in a binary polymorphic mixtures ... [more ▼]

The aim of the present study was to develop near infrared (NIR) and X-ray powder diffraction methods (XRPD) able to determine pure crystalline form II of fluconazole in a binary polymorphic mixtures containing form II and III. In order to give a first performance estimation of both methods, these latters were pre-validated using accuracy profiles, a statistical approach based on β-expectation tolerance intervals. Both methods showed a good trueness, precision and accuracy and their β-expectation tolerance intervals were fully included within the acceptance limits. The comparative study was carried out using statistical analysis based on the work of Bland and Altman. A good agreement between the two methods was demonstrated indicating the interchangeability of NIR method with XRPD method. [less ▲]

Detailed reference viewed: 68 (15 ULg)
Full Text
Peer Reviewed
See detailApplication of new methodologies based on design of experiments, independent component analysis and design space for robust optimization in liquid chromatography
Debrus, Benjamin ULg; Lebrun, Pierre ULg; Ceccato, Attilio ULg et al

in Analytica Chimica Acta (2011), 691

HPLC separations of an unknown sample mixture and a pharmaceutical formulation have been optimized using a recently developed chemometric methodology proposed by W. Dewé et al. in 2004 and improved by P ... [more ▼]

HPLC separations of an unknown sample mixture and a pharmaceutical formulation have been optimized using a recently developed chemometric methodology proposed by W. Dewé et al. in 2004 and improved by P. Lebrun et al. in 2008. This methodology is based on experimental designs which are used to model retention times of compounds of interest. Then, the prediction accuracy and the optimal separation robustness, including the uncertainty study, were evaluated. Finally, the design space (ICH Q8(R2) guideline) was computed as the probability for a criterion to lie in a selected range of acceptance. Furthermore, the chromatograms were automatically read. Peak detection and peak matching were carried out with a previously developed methodology using independent component analysis published by B. Debrus et al. in 2009. The present successful applications strengthen the high potential of these methodologies for the automated development of chromatographic methods. [less ▲]

Detailed reference viewed: 122 (41 ULg)
Full Text
Peer Reviewed
See detailOptimisation and validation of a fast HPLC method for the quantification of sulindac and its related impurities
Krier, Fabrice ULg; Brion, Michaël; Debrus, Benjamin ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2011), 54

The European Pharmacopoeia describes a liquid chromatography (LC) method for the quantification of sulindac, using a quaternary mobile phase including chloroform and with a rather long run time. In the ... [more ▼]

The European Pharmacopoeia describes a liquid chromatography (LC) method for the quantification of sulindac, using a quaternary mobile phase including chloroform and with a rather long run time. In the present study, a new method using a short sub-2μm column, which can be used on a classical HPLC system, was developed. The new LC conditions (without chloroform) were optimised by means of a new methodology based on design of experiments in order to obtain an optimal separation. Four factors were studied: the duration of the initial isocratic step, the percentage of organic modifier at the beginning of the gradient, the percentage of organic modifier at the end of the gradient and the gradient time. The optimal condition allows the separation of sulindac and of its 3 related impurities in six minutes instead of 18 min. Finally, the method was successfully validated using an accuracy profile approach in order to demonstrate its ability to accurately quantify these compounds. [less ▲]

Detailed reference viewed: 156 (51 ULg)
Full Text
Peer Reviewed
See detailEvaluating analytical results reliability using a Bayesian probability criterion
Rozet, Eric ULg; Lebrun, Pierre ULg; Boulanger, Bruno ULg et al

Poster (2010, December 02)

In pharmaceutical industries, quantitative analytical methods such as HPLC play a key role. Indeed, the analytical results obtained from them are used to make crucial decisions such as the release of ... [more ▼]

In pharmaceutical industries, quantitative analytical methods such as HPLC play a key role. Indeed, the analytical results obtained from them are used to make crucial decisions such as the release of batches of drugs, the evaluation of safety and efficacy of new drug candidates or the monitoring of patients health. Prior to their routine use, analytical methods are submitted to a stringent validation study where they have to demonstrate that they are fit for their final purpose, i.e. providing accurate result . Typically this demonstration is made by either providing point estimates of systematic error (bias) and random error (variance) or sometimes by providing interval estimates of these statistical parameters at several well defined concentration levels of the target analyte. They are then compared to maximum acceptable levels. More recently, tolerance intervals approaches have been proposed that are evaluated in a similar way at these key concentration levels. However none of these decision approaches allow knowing the probability to obtain accurate results over the whole concentration range of interest. Frequentist approximations have been proposed to estimate this probability but only at the concentration levels experimentally tested and not for the whole range of interest. In this work, a linear hierarchical Bayesian approach is proposed. It takes into account the potential random characteristic of the slope and intercept observed from one analytical run to the other, and also integrates the possible covariance between the parameters. Additionally, heteroscedasticity of the residual variance over the concentration range investigated is taken into account. A situation regularly observed in practice. Finally a reliability profile for the whole concentration range studied is obtained using MCMC sampling. This profile provides the probability (Prel) to obtain accurate results over the full concentration range investigated. This profile is then compared to a minimum reliability probability (Pmin) that will define the valid concentration range of the analytical method. The usefulness of this approach is illustrated through the validation of a bioanalytical method and also compared with a one concentration level at a time frequentist approach derived from tolerance intervals. [less ▲]

Detailed reference viewed: 60 (5 ULg)
Full Text
Peer Reviewed
See detailHow can QbD be used and implemented to optimize method development and validation?
Lebrun, Pierre ULg; Boulanger, Bruno ULg; Hubert, Philippe ULg

Conference (2010, November 04)

Through an example, the way to apply Design of Experiments and the Bayesian modeling to develop robust optimal ligand-binding assays (LBA) will be presented. The objectives of a LBA will be re-examined ... [more ▼]

Through an example, the way to apply Design of Experiments and the Bayesian modeling to develop robust optimal ligand-binding assays (LBA) will be presented. The objectives of a LBA will be re-examined and response of interest derived (precision profile). The concept of Design Space specific for LBA will be introduced in relation with validation, routine and transfer [less ▲]

Detailed reference viewed: 59 (12 ULg)
See detailPlans expérimentaux
Boulanger, Bruno ULg; Govaerts, B.; Le Boulengé, E. et al

Learning material (2010)

Vidéos du cours intitulé "Plans expérimentaux"

Detailed reference viewed: 88 (15 ULg)
Full Text
Peer Reviewed
See detailRISK MANAGMENT IN THE VALIDATION OF ANALYTICAL METHODS
Hubert, Philippe ULg; Ziemons, Eric ULg; Mantanus, Jérôme ULg et al

Conference (2010, October)

Detailed reference viewed: 125 (10 ULg)
Full Text
Peer Reviewed
See detailOptimization of ligand-binding assay in a QbD environment. Use of Bayesian non-linear regression to set up probability profile as quality response
Lebrun, Pierre ULg; Boulanger, Bruno ULg; Hubert, Philippe ULg

Conference (2010, September 28)

For ligan-binding assay, different parameters are controlled in routine. In a development phase, we will show how design of experiment can be used to select these parameters to obtain reliable results in ... [more ▼]

For ligan-binding assay, different parameters are controlled in routine. In a development phase, we will show how design of experiment can be used to select these parameters to obtain reliable results in the future use of the ELISA test. Uncertainties of measurements and models should be taken into account in a predictive manner. Bayesian modelling and MCMC simulations are well suited for this purpose and are flexible enough to include random effects on the parameters on non-linear model. We will focus on 4PL regression as it is encountered in most applications. We will also show that deriving a quality response such as a precision profile is clear and direct in the Bayesian setting. The approach is fully compliant with QbD guidelines and Design Space definition. [less ▲]

Detailed reference viewed: 90 (13 ULg)
Full Text
Peer Reviewed
See detailAnalytical tools to fight against counterfeit medicines
Marini Djang'Eing'A, Roland ULg; Mbinze Kindenge, J.; Montes, M. L. A. et al

in Chimica Oggi = Chemistry Today (2010), 28(5), 10-14

Counterfeiting has been dramatically increasing this last decade throughout the world and particularly in developing countries, with many consequences such as adverse impacts on public health, economics ... [more ▼]

Counterfeiting has been dramatically increasing this last decade throughout the world and particularly in developing countries, with many consequences such as adverse impacts on public health, economics and negative reputation for the pharmaceutical industry. Recognizing the magnitude of the issue, health authorities at national, regional and international levels are trying to fight against this scourge using various strategies including the setting-up of effective quality control that need to be reinforced through generic, fast and specific detection methods. To illustrate this topic, we will present several analytical tools, including liquid chromatography, low cost capillary electrophoresis and near infrared spectroscopy, developed and applied to the detection and quantification of counterfeit drugs. [less ▲]

Detailed reference viewed: 322 (71 ULg)