References of "Chiap, Patrice"
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See detailIntegrated on-line sample clean-up using cation exchange restricted access sorbent for the LC determination of atropine in human plasma coupled to UV detection
Rbeida, O.; Christiaens, B.; Hubert, Philippe ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2005), 36(5), 947-954

A new, simple and fully automated liquid chromatographic (LC) method with UV detection has been developed for the direct determination of atropine in plasma. Sample clean-up was based on the use of cation ... [more ▼]

A new, simple and fully automated liquid chromatographic (LC) method with UV detection has been developed for the direct determination of atropine in plasma. Sample clean-up was based on the use of cation exchange restricted access material (RAM) in a pre-column, coupled to LC by means of a column switching system. After direct injection of a 200 microl-volume of plasma sample, the biological matrix was washed out for 10 min using a washing liquid composed of 2 mM lithium perchlorate adjusted to pH 3.0 and methanol (97:3; v/v). By rotation of the switching valve, atropine was then eluted in the back-flush mode for 2 min and transferred to the analytical column packed with octadecyl silica by the LC mobile phase constituted of a mixture of acetonitrile and potassium phosphate buffer (pH 3.0; 50 mM) containing 2 mM sodium heptanesulfonate (16:84; v/v). The UV detection was performed at 220 nm. The method was validated according to a new approach based on accuracy profile over a concentration range from 25 ng/ml, corresponding to the limit of quantitation, to 1000 ng/ml. The method was then applied for the determination of atropine in plasma after intravenous administration to hospitalised patients. [less ▲]

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See detailLe transfert d’une méthode de dosage automatisée de 3 catécholamines majeures dans l’urine humaine: utilisation de l’erreur totale comme critère de décision
Rozet, Eric ULg; Dewé, W.; Chiap, Patrice ULg et al

Conference (2005)

Objectif : Un transfert analytique consiste à transférer physiquement une méthode analytique précédemment validée depuis le laboratoire émetteur vers un laboratoire receveur après avoir démontré que le ... [more ▼]

Objectif : Un transfert analytique consiste à transférer physiquement une méthode analytique précédemment validée depuis le laboratoire émetteur vers un laboratoire receveur après avoir démontré que le laboratoire receveur maîtrise la méthode. Il est donc essentiel d’avoir toutes les garanties que la méthode est en effet maîtrisée par le laboratoire receveur. Deux nouvelles approches statistiques basées sur l’utilisation de l’erreur totale comme outil de décision quant à la validité d’un transfert de méthodes analytiques ont été décrites (1). Nous nous proposons ici de montrer l’applicabilité de ces deux approches au cas du transfert d’une méthode de dosage automatique de trois catécholamines majeures dans l’urine humaine. [less ▲]

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See detailEvaluation de liquides ioniques chiraux comme sélecteurs pour des séparations électrocinétiques d'énantiomères en veine liquide capillaire
François, Yannis; Juillerat, E.; Villemin, Didier et al

Poster (2005)

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See detailUSING TOTAL ERROR AS DECISION CRITERION IN METHOD TRANSFER
Rozet, Eric ULg; Mertens, B.; Dewe, W. et al

Poster (2005)

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See detailThe Usefulness of Accuracy Profile to Validate Analytical Methods
Rozet, Eric ULg; Chiap, Patrice ULg; Dewe, W. et al

Conference (2005)

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See detailPharmacological profile and therapeutic potential of BM-573, a combined thromboxane receptor antagonist and synthase inhibitor.
Ghuysen, Alexandre ULg; Dogné, Jean-Michel; Chiap, Patrice ULg et al

in Cardiovascular Drug Reviews (2005), 23(1), 1-14

BM-573 (N-terbutyl-N'-[2-(4'-methylphenylamino)-5-nitro-benzenesulfonyl]urea), a torsemide derivative, is a novel non-carboxylic dual TXA2 synthase inhibitor and receptor antagonist. The pharmacological ... [more ▼]

BM-573 (N-terbutyl-N'-[2-(4'-methylphenylamino)-5-nitro-benzenesulfonyl]urea), a torsemide derivative, is a novel non-carboxylic dual TXA2 synthase inhibitor and receptor antagonist. The pharmacological profile of the drug is characterized by a higher affinity for the thromboxane receptor than that of SQ-29548, one of the most powerful antagonists described to date, by a complete prevention of human platelet aggregation induced by arachidonic acid at a lower dose than either torsemide or sulotroban, and by a significantly prolonged closure time measured by the platelet function analyser (PFA-100). Moreover, at the concentrations of 1 and 10 microM, BM-573 completely prevented production of TXB2 by human platelets activated by 0.6 mM of arachidonic acid. BM-573 prevents rat fundus contraction induced by U-46619 but not by prostacyclin or other prostaglandins. Despite possessing a chemical structure very similar to that of a diuretic torsemide, BM-573 has no diuretic activity. BM-573 does not prolong bleeding time and, unlike some of the other sulfonylureas, has no effect on blood glucose levels. In vivo, BM-573 appears to have antiplatelet and antithrombotic activities since it reduced thrombus weight and prolonged the time to abdominal aorta occlusion induced by ferric chloride. BM-573 also relaxed rat aorta and guinea pig trachea precontracted with U-46619. In pigs, BM-573 completely antagonized pulmonary hypertensive effects of U-46619 and reduced the early phase of pulmonary hypertension in models of endotoxic shock and pulmonary embolism. Finally, BM-573 protected pigs from myocardial infarction induced by coronary thrombosis. These results suggest that BM-573 should be viewed as a promising therapeutic agent in the treatment of pulmonary hypertension and syndromes associated with platelet activation. [less ▲]

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See detailCollaborative study of an liquid chromatographic method for the determination of R-timolol and other related substances in S-timolol maleate
Marini Djang'Eing'A, Roland ULg; Matthijs, N.; Heyden, Y. V. et al

in Analytica Chimica Acta (2005), 546(2), 182-192

A collaborative study applying an enantiomeric liquid chromatographic (LC) method was carried out to determine the content of the enantiomeric impurity R-timolol and other related substances in three ... [more ▼]

A collaborative study applying an enantiomeric liquid chromatographic (LC) method was carried out to determine the content of the enantiomeric impurity R-timolol and other related substances in three different S-timolol maleate samples. Eight laboratories, all located in Europe, participated in the study. The quantitative results obtained were used to estimate the uncertainty on the content of the different impurities. For that purpose, a set-up was adapted from the ISO guidelines 5725-2, which allowed the estimation of the different variances, i.e. the between-laboratories (s(laboratories)(2)), the between-days (s(days)(2)) and the between-replicates (s(replicates)(2)), The variances of repeatability (s(r)(2)) and reproducibility (s(R)(2)) were then calculated using the equations s(r)(2) = s(replicates)(2) and s(R)(2) = s(replicates)(2) + s(days)(2) + s(laboratories)(2). For the timolol impurities, it was found that the estimated uncertainty seem to be concentration-dependent. Since the LC method which combines the compendial ones for enantiomeric purity and related substances testing was applied to evaluate uncertainty in this collaborative study, it was shown how a laboratory can evaluate the uncertainty of its results when applying the method in the future. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailDevelopment of response models for optimising HPLC methods
Dewé, Walthère ULg; Marini Djang'Eing'A, Roland ULg; Chiap, Patrice ULg et al

in Chemometrics and Intelligent Laboratory Systems (2004), 74(2), 263-268

For optimizing a liquid chromatographic method, direct modeling some responses like minimum resolution is sometimes difficult to perform. By modeling the retention time at apex and the times associated to ... [more ▼]

For optimizing a liquid chromatographic method, direct modeling some responses like minimum resolution is sometimes difficult to perform. By modeling the retention time at apex and the times associated to 13.4% of the peak height, it is possible to obtain estimations of these responses using an adequate cascade of equations, these equations being the definitions of these responses. As a multi-criteria decision has to be taken in most of these optimizations, a Derringer's function can be defined for each response of interest and a overall desirability, on which the final is taken, can be derived. In addition, the chromatogram in any experimental point can be predicted. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailHarmonization of strategies for the validation of quantitative analytical procedures - A SFSTP proposal - part I
Hubert, Philippe ULg; Nguyen-Huu, J.-J.; Boulanger, Bruno ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2004), 36(3), 579-586

This paper is the first part of a summary report of a new commission of the Societe Francaise des Sciences et Techniques Pharmaceutiques (SFSTP). The main objective of this commission was the ... [more ▼]

This paper is the first part of a summary report of a new commission of the Societe Francaise des Sciences et Techniques Pharmaceutiques (SFSTP). The main objective of this commission was the harmonization of approaches for the validation of quantitative analytical procedures. Indeed, the principle of the validation of theses procedures is today widely spread in all the domains of activities where measurements are made. Nevertheless. this simple question of acceptability or not of an analytical procedure for a given application, remains incompletely determined in several cases despite the various regulations relating to the good practices (GLP, GMP,...) and other documents of normative character (ISO, ICH. FDA,...). There are many official documents describing the criteria of validation to be tested, but they do not propose any experimental protocol and limit themselves most often to the general concepts. For those reasons, two previous SFSTP commissions elaborated validation guides to concretely help the industrial scientists in charge of drug development to apply those regulatory recommendations. If these two first guides widely contributed to the use and progress of analytical validations, they present, nevertheless, weaknesses regarding the conclusions of the performed statistical tests and the decisions to be made with respect to the acceptance limits defined by the use of an analytical procedure. The present paper proposes to review even the bases of the analytical validation for developing harmonized approach, by distinguishing notably the diagnosis rules and the decision rules. This latter rule is based on the use of the accuracy profile, uses the notion of total error and allows to simplify the approach of the validation of an analytical procedure while checking the associated risk to its usage. Thanks to this novel validation approach, it is possible to unambiguously demonstrate the fitness for purpose of a new method as stated in all regulatory documents. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailFully automated method for the liquid chromatographic-tandem mass spectrometric determination of cyproterone acetate in human plasma using restricted access material for on-line sample clean-up
Christiaens, B.; Fillet, Marianne ULg; Chiap, Patrice ULg et al

in Journal of Chromatography. A (2004), 1056(1-2), 105-110

A new automated method for the quantitative analysis of cyproterone acetate (CPA) in human plasma has been developed using on-line solid phase extraction (SPE) prior to the LC-MS/MS determination. The ... [more ▼]

A new automated method for the quantitative analysis of cyproterone acetate (CPA) in human plasma has been developed using on-line solid phase extraction (SPE) prior to the LC-MS/MS determination. The method was based on the use of a pre-column packed with internal-surface reversed-phase material (LiChrospher RP-4 ADS, 25 mm x 2 mm) for sample clean-up coupled to LC separation on an octadecyl silica stationary phase by means of a column switching system. A 30 microl plasma sample volume was injected directly onto the pre-column using a mixture of water, acetonitrile and formic acid (90:10:0.1 (v/v/v)) adjusted to pH 4.0 with diluted ammonia as washing liquid. The analyte was then eluted in the back-flush mode with the LC mobile phase consisting of water, methanol and formic acid (10:90:0.1 (v/v/v)). The dispensing flow rates of the washing liquid and the LC mobile phase were 300 microl min(-1). Medroxyprogesterone acetate (MPA) was used as internal standard. The MS ionization of the analytes was achieved using electrospray (ESI) in the positive ion mode. The pseudomolecular ionic species of CPA and MPA (417.4 and 387.5) were selected to generate daughter ions at 357.4 and 327.5, respectively. Finally, the developed method was validated according to a new approach using accuracy profiles as a decision tool. Very good results with respect to accuracy, detectability, repeatability, intermediate precision and selectivity were obtained. The LOQ of cyproterone acetate was 300 pg ml(-1). [less ▲]

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See detailDevelopment and validation of a high-performance liquid chromatographic method for the determination of cyproterone acetate in human skin
Henry de Hassonville, Sandrine; Chiap, Patrice ULg; Liégeois, Jean-François ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2004), 36(1), 133-143

In the framework of a preliminary study on the transdermal penetration of cyproterone acetate (CPA), a simple and rapid procedure involving an extraction step coupled to a HPLC-UV determination has been ... [more ▼]

In the framework of a preliminary study on the transdermal penetration of cyproterone acetate (CPA), a simple and rapid procedure involving an extraction step coupled to a HPLC-UV determination has been developed for the separation and quantification of CPA in the two main skin layers-epidermis and dermis-after local application. The separation of epidermis and dermis layers was carefully carried out by means of a sharp spatula after skin immersion in heated water at 65 degrees C. The two skin layers were then treated separately according to the same process: (1) sample homogenization by vibration after freezing with liquid nitrogen in a Mikro-Dismembrator; (2) CPA extraction with methanol after addition of the internal standard (betamethasone dipropionate); (3) centrifugation; (4) evaporation of a supernatant aliquot; (5) dissolution of the dry residue in methanol and addition of water; (6) centrifugation; (7) injection of a supernatant aliquot into the HPLC system. The separation was achieved on octadecylsilica stationary phase using a mobile phase consisting in a mixture of acetonitrile and water (40:60 (v/v)). The method was then validated using a new approach based on accuracy profiles over a CPA concentration range from 33 to 667 ng/ml for each skin layer. Finally, the method was successfully applied to the determination of CPA to several skin samples after topical application of different gel formulations containing CPA. [less ▲]

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See detailDevelopment and validation of a high performance liquid chromatographic method for quantitative determination of aporphine alkaloids from different samples of Cassytha filiformis
Stevigny, C.; Wautier, M. C.; Jiwan, J. L. H. et al

in Planta Medica (2004), 70(8), 764-770

A sensitive and accurate procedure based on an alkaloid extraction coupled to an HPLC-UV-MS determination has been developed for the separation and quantification of the major aporphines in Cassytha ... [more ▼]

A sensitive and accurate procedure based on an alkaloid extraction coupled to an HPLC-UV-MS determination has been developed for the separation and quantification of the major aporphines in Cassytha filiformis. The extraction step and the liquid chromatography conditions were optimized in order to improve the selectivity of the method. The HPLC mobile phase consisted of a mixture of water containing 10 mM ammonium acetate adjusted to pH 3 with acetic acid-acetonitrile (90: 10, v/v) (A) and acetonitrile (B) used in a gradient mode (0 to 40%). The stationary phase was an RP-select B (5 mum) column. The method was completely validated using cassythine, one of the major aporphines in our samples, as reference standard and successfully applied to the determination of these pharmacologically interesting aporphines in seven different batches of C. filiformis. The detection and quantitation limits of cassythine were found to be 13 and 20 mug/mL, respectively. The results showed variations in the total alkaloid content in samples from 0.11 to 0.43%. [less ▲]

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