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See detailMonitoring of urea and potassium by reverse iontophoresis in vitro
Wascotte, Valentine; Delgado-Charro, Begona; Rozet, Eric ULg et al

in Pharmaceutical Research (2007), 24(6), 1131-1137

Purpose. Reverse iontophoresis is an alternative to blood sampling for the monitoring of endogenous molecules. Here, the potential of the technique to measure urea and potassium levels non-invasively, and ... [more ▼]

Purpose. Reverse iontophoresis is an alternative to blood sampling for the monitoring of endogenous molecules. Here, the potential of the technique to measure urea and potassium levels non-invasively, and to track their concentrations during hemodialysis, has been examined. Materials and Methods. In vitro experiments were performed to test (a) a series of subdermal urea and potassium concentrations typical of the pathophysiologic range, and (b) a decreasing profile of urea and potassium subdermal concentrations to mimic those which are observed during hemodialysis. Results. (a) After 60-120 min of iontophoresis, linear relationships (p < 0.05) were established between both urea and potassium fluxes and their respective subdermal concentrations. The determination coefficients were above 0.9 after 1 h of current passage using sodium as an internal standard. (b) Reverse iontophoretic fluxes of urea and K+ closely paralleled the decay of the respective concentrations in the subdermal compartment, as would occur during a hemodialysis session. Conclusions. These in vitro experiments demonstrate that urea and potassium can be quantitatively and proportionately extracted by reverse iontophoresis, even when the subdermal concentrations of the analytes are varying with time. These results suggest the non-invasive monitoring of urea and potassium to diagnose renal failure and during hemodialysis is feasible, and that in vivo measurements are warranted. [less ▲]

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See detailCyclodextrin-mediated drug release from liposomes dispersed within a bioadhesive gel
Piel, Géraldine ULg; Boulmedarat, Laila; Bochot, Amelie et al

in Pharmaceutical Research (2005), 22(6), 962-971

Purpose. The aim of the present study was to design a new mucosal drug delivery system composed of liposomes dispersed within a bioadhesive hydrogel containing methyl-beta-cyclodextrin (Me beta CD) for ... [more ▼]

Purpose. The aim of the present study was to design a new mucosal drug delivery system composed of liposomes dispersed within a bioadhesive hydrogel containing methyl-beta-cyclodextrin (Me beta CD) for controlled drug release. Methods. A hydrophilic model molecule, inulin, was encapsulated within positively charged and PEGylated liposomes and its release was measured in the presence of Me beta CD after vesicle dispersion within the bioadhesive Carbopol(R) 974P gel. Freeze-fracture electron microscopy (FFEM) was used to follow liposome morphological changes when dispersed within the hydrogel. Liposome- Me beta CD interactions were investigated by turbidity monitoring during continuous addition of Me beta CD to liposomes and by FFEM. Results. Inulin diffusion within the gel was influenced by Carbopol(R) 974P concentration since no gel erosion occurred. When dispersed within the gel, positively charged liposomes displayed a higher stability than PEG-ylated vesicles. In the presence of Me beta CD, higher amounts of free inulin were released from liposomes, especially in Carbopol(R)-free system. Me beta CD appeared to diffuse towards lipid vesicles and permeabilized their bilayer allowing inulin leakage. Indeed, freeze-fracture experiments and liposome turbidity monitoring have shown that Me beta CD behaved as a detergent behavior, resulting in lipid vesicle solubilization. Conclusion. Me beta CD is able to mediate, within a bioadhesive hydrogel, the release of a liposome-encapsulated molecule allowing further application of this delivery system for mucosal administration. [less ▲]

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See detailEnhancement of transfection efficiency through rapid and noncovalent post-PEGylation of poly(dimethylaminoethyl methacrylate)/DNA complexes
Pirotton, S.; Muller, Caroline; Pantoustier, N. et al

in Pharmaceutical Research (2004), 21(8), 1471-1479

Purpose. The aim of this work was to develop a new strategy to introduce poly(ethylene glycol) (PEG) into methacrylate-based polymer/ DNA complexes in order to produce hemocompatible particles able to ... [more ▼]

Purpose. The aim of this work was to develop a new strategy to introduce poly(ethylene glycol) (PEG) into methacrylate-based polymer/ DNA complexes in order to produce hemocompatible particles able to transfect cells in the presence of serum. Methods. Atom transfer radical polymerization was used to synthesize a well-defined poly(2-(dimethylamino) ethyl methacrylate) homopolymer ( PDMAEMA) and a poly( 2-( dimethylamino) ethyl methacrylate-b-poly( ethylene glycol) alpha-methyl ether, omega-methacrylate) palm-tree-like copolymer (P(DMAEMA-b-MAPEG)). The complexes obtained by self assembly of the pCMVbeta plasmid and the polymers were used to transfect Cos-7 cells. Their physical properties - particle size and zeta potential - were characterized respectively by dynamic light scattering and electrophoretic mobility measurements. Ex vivo hemocompatibility was also determined. Results. The PDMAEMA/pCMVbeta complexes transfected Cos-7 cells exclusively in the absence of serum. Although the P(DMAEMA-b-MAPEG) copolymer had no transfection activity per se, the addition of the latter to pre-formed PDMAEMA/DNA complexes significantly enhanced the activity and allowed transfection even in the presence of serum. The presence of palm-tree - like copolymers also improved the hemocompatibility properties of the complexes. No effect on platelet counts was observed for P(DMAEMA-b-MAPEG)/ pCMVbeta complexes, whereas a decrease of platelets was clearly observed when blood cells were incubated with PDMAEMA/pCMVbeta complexes. Conclusions. Such a synergistic effect of noncovalent PEGylation of poly( amino methacrylate)/ DNA complexes allows a new and versatile approach to tune up transfection efficiency. [less ▲]

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See detailCell Handling, Membrane-Binding Properties, And Membrane-Penetration Modeling Approaches Of Pivampicillin And Phthalimidomethylampicillin, Two Basic Esters Of Ampicillin, In Comparison With Chloroquine And Azithromycin
Chanteux, H.; Paternotte, I.; Mingeot-Leclercq, Mp. et al

in Pharmaceutical Research (2003), 20(4), 624-31

PURPOSE: The purpose of this work was to examine and understand the cellular pharmacokinetics of two basic esters of ampicillin, pivaloyloxymethyl (PIVA) and phthalimidomethyl (PIMA), in comparison with ... [more ▼]

PURPOSE: The purpose of this work was to examine and understand the cellular pharmacokinetics of two basic esters of ampicillin, pivaloyloxymethyl (PIVA) and phthalimidomethyl (PIMA), in comparison with lysosomotropic drugs (chloroquine, azithromycin). METHODS: Cell culture studies (J774 macrophages) were undertaken to study uptake and release kinetics and to assess the influence of concentration, pH, proton ionophore (monensin), and MRP and P-gp inhibitors (probenecid, gemfibrozil, cyclosporin A, GF 120918). Equilibrium dialysis with liposomes were performed to directly asses the extent of drug binding to bilayers. Conformational analysis modeling of the drug penetration in bilayers was conducted to rationalize the experimental observations. RESULTS: PIVA and PIMA showed properties in almost complete contrast with those of chloroquine and azithromycin, i.e., fast apparent accumulation and fast release at 4 degrees C as well as at 37 degrees C, saturation of uptake (apparent Kd 40 microM), no influence of monensin, MRP, or P-gp inhibitors; tight binding to liposomes (Kd approx. 40 microM); and sharp increase in calculated free energy when forced in the hydrophobic domain. CONCLUSIONS: Although they are weak organic bases, PIVA and PIMA show none of the properties of lysosomotropic agents. We hypothesize that they remain locked onto the pericellular membrane and may never penetrate cells as such in significant amounts. [less ▲]

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See detailApplication of Supercritical Carbon Dioxide for the Preparation of a Piroxicam-Beta-Cyclodextrin Inclusion Compound
Van Hees, Thierry ULg; Piel, Géraldine ULg; Evrard, Brigitte ULg et al

in Pharmaceutical Research (1999), 16(12), 1864-70

PURPOSE: Piroxicam is a poorly soluble NSAID, whose solubility is enhanced when included into beta-cyclodextrin. The preparation of a piroxicam-beta-cyclodextrin inclusion compound using supercritical CO2 ... [more ▼]

PURPOSE: Piroxicam is a poorly soluble NSAID, whose solubility is enhanced when included into beta-cyclodextrin. The preparation of a piroxicam-beta-cyclodextrin inclusion compound using supercritical CO2 was investigated. METHODS: The solubility and the stability of piroxicam in supercritical CO2 were determined. Then, the influence of the temperature, the pressure and the time of exposure on the inclusion rate was studied. RESULTS: The solubility of piroxicam varied over a wide range depending on the temperature and pressure (from 0.006 to 1.500 mg/g of CO2). The temperature and the time of exposure had a great influence on the inclusion yield, while pressure did not and a complete inclusion was achieved by keeping a physical mixture of piroxicam and beta-cyclodextrin (1:2.5 mol/mol) for 6 hours at 150 degrees C and 15 MPa of CO2. This complex was characterized by Differential Scanning Calorimetry, differential solubility and Fourier Transform Infrared Spectrometry. CONCLUSIONS: Supercritical carbon dioxide may prove to be a novel useful complexation method of drugs into beta-cyclodextrin. [less ▲]

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See detailPolylactide Microparticules Prepared by Double Emulsion/Evaporation Technique. I. Effect of Primary Emulsion Stability
Nihant; Schugens, Chantal; Grandfils, Christian ULg et al

in Pharmaceutical Research (1994), 11(10), 1479-1484

The process of microencapsulation of proteins by double emulsion-evaporation in a matrix of polylactide (PLA) can be divided into three successive steps: first, an aqueous solution of the active compound ... [more ▼]

The process of microencapsulation of proteins by double emulsion-evaporation in a matrix of polylactide (PLA) can be divided into three successive steps: first, an aqueous solution of the active compound is emulsified into an organic solution of the hydrophobic coating polymer; second, this primary water-in-oil (w/o) is dispersed in water with formation of a double water-oil-water emulsion (w/o/w), third, the organic solvent is removed with formation of solid microparticles. This paper focuses of the effect of primary emulsion stability on the morphology and properties of polylactide microparticles loaded with bovine serum albumin (BSA) used as model drug. [less ▲]

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