References of "Hubert, Philippe"
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See detailCZE separation of basic and acidic drug by use of cyclodextrin additives
Bechet, I.; Fillet, Marianne ULg; Fotsing, Lucas ULg et al

Poster (1995)

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See detailBiopharmaceutical aspects of the development of a sulfamethazine oral sustained release bolus for lambs
Evrard, Brigitte ULg; Delahaut, P.; Hubert, Philippe ULg et al

in Journal of Controlled Release (1995), 35

Pharmacokinetic parameters of sulfamethazine (SMZ) administered intravenously or orally either as an aqueous solution or as a lipid matrix formulation, were determined in young lambs. The value of the ... [more ▼]

Pharmacokinetic parameters of sulfamethazine (SMZ) administered intravenously or orally either as an aqueous solution or as a lipid matrix formulation, were determined in young lambs. The value of the rate constant for elimination (ke) for the intravenous solution was 0.18 h−1 compared to 0.10 h−1 for the oral aqueous solution. The absolute bioavailability of the oral solution was about 75%. A lipid matrix containing SMZ and a high density excipient is able to be retained in the reticulo-rumen and to produce a sustained release of the drug for at least 100 h provided that the mechanical strength of the bolus is sufficient. The pharmacokinetic data obtained with the lipid matrix show a release profile with two pulses due to both diffusion and erosion mechanisms. Plasma levels are maintained above the MIC of SMZ during 100 h with an absolute bioavailability of 51.7% [less ▲]

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See detailDetermination of Benzodiazepines by Micellar Electrokinetic Chromatography
Bechet, I.; Fillet, Marianne ULg; Hubert, Philippe ULg et al

in Electrophoresis (1994), 15(10), 1316-21

A method for the separation and determination of benzodiazepines by micellar electrokinetic chromatography (MEKC) has been developed. Separation buffers consisted of aqueous solutions of glycine and ... [more ▼]

A method for the separation and determination of benzodiazepines by micellar electrokinetic chromatography (MEKC) has been developed. Separation buffers consisted of aqueous solutions of glycine and triethanolamine (pH 9.0), containing sodium dodecyl sulfate (SDS) as surfactant and methanol as organic modifier. The effect of the concentration of SDS, methanol, glycine and triethanolamine on migration times and resolution was studied. Ten benzodiazepines were baseline separated at a 25 mM SDS concentration and 20% v/v methanol in a 75 mM glycine-250 mM triethanolamine buffer. Under these conditions, the within-day reproducibilities were 0.3-0.5% for migration times and 1.7-1.9% for peak areas at a concentration of 10 micrograms/mL. The limits of detection and quantification for oxazepam were 0.2 and 0.7 micrograms/mL, respectively, using an injection time of 5 s. [less ▲]

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See detailChiral Separation of Basic Drugs by Capillary Zone Electrophoresis with Cyclodextrin Additives
Bechet, I.; Paques, P.; Fillet, Marianne ULg et al

in Electrophoresis (1994), 15(6), 818-23

The enantiomers of a series of basic drugs were separated in capillary zone electrophoresis (CZE) in phosphate buffers, pH 3, containing beta-cyclodextrin or one of its derivatives as chiral selectors and ... [more ▼]

The enantiomers of a series of basic drugs were separated in capillary zone electrophoresis (CZE) in phosphate buffers, pH 3, containing beta-cyclodextrin or one of its derivatives as chiral selectors and uncoated fused silica capillaries thermostated at 15 degrees C. The nature of the cationic component of the background electrolyte was found to have a significant influence on achiral resolution and peak symmetry. The best results were obtained with triethanolamine, which was then used to adjust the buffer pH in all further experiments. The effects on chiral resolution of the nature and concentration of cyclodextrin, of the addition of methanol, and of capillary temperature were studied. Maximum resolution was obtained at a particular cyclodextrin concentration for each analyte, depending on the affinity of the analyte for this cyclodextrin. On the basis of the results, the effects of methanol addition and temperature on enantiomeric resolution could be explained and predicted. Numerous chiral separations are presented and suggestions for the rapid optimization of CZE enantioseparations with cyclodextrin additives are given. [less ▲]

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See detailKnowledge-Based System for the Automated Solid-Phase Extraction of Basic Drugs from Plasma Coupled with Their Liquid Chromatographic Determination. Application to the Biodetermination of Beta-Receptor Blocking Agents
Hubert, Philippe ULg; Chiap, Patrice ULg; Moors, M. et al

in Journal of Chromatography. A (1994), 665(1), 87-99

Techniques for the preparation of biological samples are often based nowadays on solid-phase extraction (SPE). The different SPE steps can be performed automatically on disposable extraction cartridges ... [more ▼]

Techniques for the preparation of biological samples are often based nowadays on solid-phase extraction (SPE). The different SPE steps can be performed automatically on disposable extraction cartridges (DECs) by means of a sample processor. A knowledge-based system was developed to facilitate the development of fully automated methods for the solid-phase extraction of relatively hydrophobic basic drugs from plasma, coupled with their determination by high-performance liquid chromatography (HPLC). The DEC filled with 50 mg of cyanopropyl-bonded silica phase is first conditioned with methanol and buffer solution (pH 7.4). After sample application, the DEC sorbent is washed with the same buffer. The analytes are then desorbed with an appropriate eluent and the eluate is finally diluted with the same buffer as used in the HPLC mobile phase before injection. Under these conditions, only three variables are still to be optimized: the composition and volume of the elution solvent and the volume of buffer to be added to the eluate. On the basis of this general strategy, a decision tree providing information about suggested starting conditions and guidelines for the optimization of the three variables was developed and implemented by use of a hypermedia software. This didactic expert system was evaluated using several beta-receptor blocking agents as model compounds and the operating conditions obtained for the automated SPE of these compounds are presented. A method for the determination of propranolol in plasma using the SPE conditions deduced from the knowledge-based system was validated. The absolute recovery of propranolol is ca. 93% and the limit of detection is 1.3 ng ml-1. The mean within-day and between-day reproducibilities are 2.3 and 3.6%, respectively. [less ▲]

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See detailQuantitative analysis of B-adrenergic blocking agents by capillary zone electrophoresis
Bechet, I.; Fillet, Marianne ULg; Hubert, Philippe ULg et al

in Journal de Pharmacie de Belgique (1994), 49

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See detailA knowledge-based system for developping solid-phase extraction methods with the ASPEC system, chapitre #D-3
Moors, M.; Bourguignon, B.; Massart, D. L. et al

in Reid, E.; Hill, H. M.; Wilson, I. D. (Eds.) Biofluid and tissue analysis for drugs, including hypolipidaemics (1994)

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See detailDetermination of Non-Steroidal Anti-Inflammatory Drugs by Capillary Zone Electrophoresis
Bechet, I.; Paques, Ph.; Fillet, Marianne ULg et al

Poster (1994)

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See detailDetermination of acidic and basic drugs by capillary zone electrophoresis
Crommen, Jacques ULg; Bechet, I.; Fillet, Marianne ULg et al

Conference (1994)

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See detailDrug quality control by capillary electrophoresis
Crommen, Jacques ULg; Bechet, I.; Fillet, Marianne ULg et al

Conference (1994)

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See detailFully Automated Determination of Sulfamethazine in Ovine Plasma Using Solid-Phase Extraction on Disposable Cartridges and Liquid Chromatography
Hubert, Philippe ULg; Chiap, Patrice ULg; Evrard, Brigitte ULg et al

in Journal of Chromatography. A (1993), 622(1), 53-60

An automatic sample preparation procedure followed by on-line injection of the sample extract into a HPLC system has been developed for the quantitative analysis of sulfamethazine and its N4-acetyl ... [more ▼]

An automatic sample preparation procedure followed by on-line injection of the sample extract into a HPLC system has been developed for the quantitative analysis of sulfamethazine and its N4-acetyl metabolite in ovine plasma. The sample clean-up was performed by solid-phase extraction (SPE) on C18 disposable extraction cartridges (DECs). All the sample handling operations were effected by a robotic auto-sampler. The DEC was first conditioned with methanol and phosphate buffer pH 7.4. After loading 1.0 ml of plasma sample onto the DEC, the latter was washed with the same buffer. The elution step was performed with methanol (0.25 ml) and the eluate was then diluted by adding 0.75 ml volume of phosphate buffer pH 6.4. A 20-microliters volume of the resultant solution was injected onto an octadecyl silica column preceded by a short guard column. The HPLC mobile phase was methanol-phosphate buffer pH 6.4 (25:75, v/v). Sulfamethazine and N4-acetylsulfamethazine were determined photometrically at 262 nm. Under these conditions, linear calibration curves ranging from 2 to 250 micrograms ml-1 have been obtained for both compounds. Drug recoveries were higher than 90% and typical relative standard deviation values were 0.7% (within-day) and 2.0% (between-day) at a plasma concentration of 50 micrograms ml-1. [less ▲]

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See detailMethod developement and applications of capillary electrophoresis in drug analysis
Crommen, Jacques ULg; Bechet, I.; Paques, Ph. et al

Conference (1993)

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