The Experts below are selected from a list of 147 Experts worldwide ranked by ideXlab platform
Pablo Fernández López - One of the best experts on this subject based on the ideXlab platform.
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direct analysis of amiloride and Triamterene mixtures by fluorescence spectrometry using partial least squares calibration
Analytica Chimica Acta, 2001Co-Authors: José A.murillo Pulgarín, Aurelia Alañón Molina, Pablo Fernández LópezAbstract:Abstract The simultaneous determination of amiloride and Triamterene in urine samples using fluorimetry in combination with partial-least squares (PLS) multivariate calibration is proposed. Triamterene and amiloride exhibit overlapped spectra and urine produces background fluorescence that precludes the direct determination of these diuretics by conventional fluorimetry. Although, the qualitative composition of the fluorescent metabolites in urine from healthy people is virtually invariable, their quantitative composition exhibits some differences. Thus, the shape of the spectrum and the position of the fluorescence maxima change as the urine is diluted. The determination was performed in a 1:1 (v/v) ethanol /water medium at an apparent pH of 6.3 provided by 0.01 M sodium citrate/citric acid buffer. An excitation wavelength of 365 nm was used for both amiloride and Triamterene. The corresponding emission maxima were located at 413 and 437 nm for amiloride and Triamterene, respectively. A calibration set consisting of samples standards was used in combination with a factor design; two levels per factor and a central star design (i.e. a central composite design) were used. In order to ensure accurate results, the calibration matrix was implement an urine sample containing no Triamterene or amiloride (i.e. urine blank). The components of the calibration matrix were Triamterene, amiloride and urine. The concentration of amiloride was varied from 64 to 320 ng/ml and that of Triamterene from 20 to 100 ng/ml. Urine dilution was varied from 1:35 to 1:65. Urine was used as the third component of the calibration matrix in order to include the information inherent in changes in the fluorescence spectrum for urine upon dilution.
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Direct analysis of amiloride and Triamterene mixtures by fluorescence spectrometry using partial-least squares calibration
Analytica Chimica Acta, 2001Co-Authors: José A.murillo Pulgarín, Aurelia Alañón Molina, Pablo Fernández LópezAbstract:The simultaneous determination of amiloride and Triamterene in urine samples using fluorimetry in combination with partial-least squares (PLS) multivariate calibration is proposed. Triamterene and amiloride exhibit overlapped spectra and urine produces background fluorescence that precludes the direct determination of these diuretics by conventional fluorimetry. Although, the qualitative composition of the fluorescent metabolites in urine from healthy people is virtually invariable, their quantitative composition exhibits some differences. Thus, the shape of the spectrum and the position of the fluorescence maxima change as the urine is diluted. The determination was performed in a 1:1 (v/v) ethanol /water medium at an apparent pH of 6.3 provided by 0.01 M sodium citrate/citric acid buffer. An excitation wavelength of 365 nm was used for both amiloride and Triamterene. The corresponding emission maxima were located at 413 and 437 nm for amiloride and Triamterene, respectively. A calibration set consisting of samples standards was used in combination with a factor design; two levels per factor and a central star design (i.e. a central composite design) were used. In order to ensure accurate results, the calibration matrix was implement an urine sample containing no Triamterene or amiloride (i.e. urine blank). The components of the calibration matrix were Triamterene, amiloride and urine. The concentration of amiloride was varied from 64 to 320 ng/ml and that of Triamterene from 20 to 100 ng/ml. Urine dilution was varied from 1:35 to 1:65. Urine was used as the third component of the calibration matrix in order to include the information inherent in changes in the fluorescence spectrum for urine upon dilution. © 2001 Elsevier Science B.V. All rights reserved.
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direct determination of Triamterene in urine by matrix isopotential synchronous fluorescence spectrometry
Analytica Chimica Acta, 1996Co-Authors: José A.murillo Pulgarín, Alanon A Molina, Pablo Fernández LópezAbstract:Abstract A new method for the determination of Triamterene for concentrations between 10 and 1000ng ml −1 by means of matrix isopotential synchronous fluorescence spectrometry and derivative techniques is proposed. This new method is useful for the determination of compounds in samples with unknown background fluorescence, such as Triamterene in urine, without the need of tedious pre-separation. The determination was performed in an aqueous medium adjusted at a pH value of 6.2, provided by adding sodium citrate-citric acid buffer solution. Since Triamterene is widely used as a doping substance in sport, the method was successfully applied to the determination of Triamterene in urine. Better sensitivity and repeatability are achieved for these matrices with the proposed method than with the fluorimetric ones described in the literature. An extensive statistical analysis has been developed to all calibration graphs. This treatment includes robust regression such as least median of squares which also detects outliers and leverage points. The weighted least squares regression has been applied to find the more exact straight line which fits the experimental data. The error propagation has been used for the calculation of the detection limit, determination limit and the repeatability of the method.
José A.murillo Pulgarín - One of the best experts on this subject based on the ideXlab platform.
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direct analysis of amiloride and Triamterene mixtures by fluorescence spectrometry using partial least squares calibration
Analytica Chimica Acta, 2001Co-Authors: José A.murillo Pulgarín, Aurelia Alañón Molina, Pablo Fernández LópezAbstract:Abstract The simultaneous determination of amiloride and Triamterene in urine samples using fluorimetry in combination with partial-least squares (PLS) multivariate calibration is proposed. Triamterene and amiloride exhibit overlapped spectra and urine produces background fluorescence that precludes the direct determination of these diuretics by conventional fluorimetry. Although, the qualitative composition of the fluorescent metabolites in urine from healthy people is virtually invariable, their quantitative composition exhibits some differences. Thus, the shape of the spectrum and the position of the fluorescence maxima change as the urine is diluted. The determination was performed in a 1:1 (v/v) ethanol /water medium at an apparent pH of 6.3 provided by 0.01 M sodium citrate/citric acid buffer. An excitation wavelength of 365 nm was used for both amiloride and Triamterene. The corresponding emission maxima were located at 413 and 437 nm for amiloride and Triamterene, respectively. A calibration set consisting of samples standards was used in combination with a factor design; two levels per factor and a central star design (i.e. a central composite design) were used. In order to ensure accurate results, the calibration matrix was implement an urine sample containing no Triamterene or amiloride (i.e. urine blank). The components of the calibration matrix were Triamterene, amiloride and urine. The concentration of amiloride was varied from 64 to 320 ng/ml and that of Triamterene from 20 to 100 ng/ml. Urine dilution was varied from 1:35 to 1:65. Urine was used as the third component of the calibration matrix in order to include the information inherent in changes in the fluorescence spectrum for urine upon dilution.
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Direct analysis of amiloride and Triamterene mixtures by fluorescence spectrometry using partial-least squares calibration
Analytica Chimica Acta, 2001Co-Authors: José A.murillo Pulgarín, Aurelia Alañón Molina, Pablo Fernández LópezAbstract:The simultaneous determination of amiloride and Triamterene in urine samples using fluorimetry in combination with partial-least squares (PLS) multivariate calibration is proposed. Triamterene and amiloride exhibit overlapped spectra and urine produces background fluorescence that precludes the direct determination of these diuretics by conventional fluorimetry. Although, the qualitative composition of the fluorescent metabolites in urine from healthy people is virtually invariable, their quantitative composition exhibits some differences. Thus, the shape of the spectrum and the position of the fluorescence maxima change as the urine is diluted. The determination was performed in a 1:1 (v/v) ethanol /water medium at an apparent pH of 6.3 provided by 0.01 M sodium citrate/citric acid buffer. An excitation wavelength of 365 nm was used for both amiloride and Triamterene. The corresponding emission maxima were located at 413 and 437 nm for amiloride and Triamterene, respectively. A calibration set consisting of samples standards was used in combination with a factor design; two levels per factor and a central star design (i.e. a central composite design) were used. In order to ensure accurate results, the calibration matrix was implement an urine sample containing no Triamterene or amiloride (i.e. urine blank). The components of the calibration matrix were Triamterene, amiloride and urine. The concentration of amiloride was varied from 64 to 320 ng/ml and that of Triamterene from 20 to 100 ng/ml. Urine dilution was varied from 1:35 to 1:65. Urine was used as the third component of the calibration matrix in order to include the information inherent in changes in the fluorescence spectrum for urine upon dilution. © 2001 Elsevier Science B.V. All rights reserved.
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direct determination of Triamterene in urine by matrix isopotential synchronous fluorescence spectrometry
Analytica Chimica Acta, 1996Co-Authors: José A.murillo Pulgarín, Alanon A Molina, Pablo Fernández LópezAbstract:Abstract A new method for the determination of Triamterene for concentrations between 10 and 1000ng ml −1 by means of matrix isopotential synchronous fluorescence spectrometry and derivative techniques is proposed. This new method is useful for the determination of compounds in samples with unknown background fluorescence, such as Triamterene in urine, without the need of tedious pre-separation. The determination was performed in an aqueous medium adjusted at a pH value of 6.2, provided by adding sodium citrate-citric acid buffer solution. Since Triamterene is widely used as a doping substance in sport, the method was successfully applied to the determination of Triamterene in urine. Better sensitivity and repeatability are achieved for these matrices with the proposed method than with the fluorimetric ones described in the literature. An extensive statistical analysis has been developed to all calibration graphs. This treatment includes robust regression such as least median of squares which also detects outliers and leverage points. The weighted least squares regression has been applied to find the more exact straight line which fits the experimental data. The error propagation has been used for the calculation of the detection limit, determination limit and the repeatability of the method.
J M Gines - One of the best experts on this subject based on the ideXlab platform.
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thermal study of complex formation of Triamterene with β cyclodextrin by spray drying and co grinding
Journal of Thermal Analysis and Calorimetry, 1995Co-Authors: J M Gines, M J Arias, Csaba Novak, P J Sanchezsoto, Antonio Ruizconde, E MorilloAbstract:The formation of crystalline inclusion complex of Triamterene with β-cyclodextrin (β-CD) was studied, evaluating the thermal behaviour and dispersion state of this drug in different types of binary systems. Spray-drying and co-grinding (oscillating mill) mixtures of triameterene with β-CD were prepared in 1∶1 molar ratio. The changes of crystalline properties of original (untreated) Triamterene, β-CD, and composites obtained by co-grinding and spray-drying were investigated in comparison with those produced in simple physical mixtures. The thermal behaviour of the different samples was investigated using DTA. X-ray diffraction was applied as a complementary technique. The results have been explained by formation of amorphous drug particles on spray-drying samples and co-grinding or alternatively by means of a solid dispersion formation or a combination of these two. A contamination effect by grinding media was also observed as increasing grinding time.
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Improvement of the diuretic effect of Triamterene via solid dispersion technique with PEG 4000
European Journal of Drug Metabolism and Pharmacokinetics, 1994Co-Authors: M J Arias, J M Gines, J. R. Moyano, M. J. Perez-barrales, M. T. Vela, A M RabascoAbstract:The present investigation was designed and undertaken in order to substantiate further contention concerning the universality of the utilization of PEG polymers as matrix carriers. This study could then be considered an attempt to enhance the dissolution rate of Triamterene, with the subsequent enhancement in its absorption rate, via solid dispersion using PEG 4000. The approach of solid dispersions was found useful for optimizing the pharmacokinetic of Triamterene in rats.
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thermal analysis of the system Triamterene d mannitol
Journal of Thermal Analysis and Calorimetry, 1994Co-Authors: J M Gines, M J Arias, A M Rabasco, P J SanchezsotoAbstract:Thermal analysis (DSC and HSM), and equilibrium solubility determinations were carried out to elucidate the mechanism of interaction at the solid state in the binary system Triamterene-D-mannitol. Physical mixtures (5–90% w/w Triamterene) and solid dispersions (5 up to 40% w/w Triamterene) were prepared and studied.
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dissolution rate study of fresh and aging Triamterene urea solid dispersions
Drug Development and Industrial Pharmacy, 1994Co-Authors: J M Gines, M J Arias, M A Holgado, M F Arevalo, A M RabascoAbstract:Triamterene-urea solid dispersions of varying weight fractions were elaborated by the melting carrier method and their dissolution profiles compared with the pure drug and physical mixtures. The dissolution rates of Triamterene from solid dispersions were faster than the pure drug and physical mixtures.Solubility studies revealed a linear increase in the solubility of the Triamterene with the increase of urea concentration.The intrinsic dissolution rates, determined by the rotating disc method, showed linear dissolution profiles in spite of that the scanning electron microscopy examination revealed that the surfaces do not maintain constant during the dissolution process.Aging of the different preparations for one year at room temperature does not induced significant changes in their dissolution profiles.
P J Sanchezsoto - One of the best experts on this subject based on the ideXlab platform.
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thermal study of complex formation of Triamterene with β cyclodextrin by spray drying and co grinding
Journal of Thermal Analysis and Calorimetry, 1995Co-Authors: J M Gines, M J Arias, Csaba Novak, P J Sanchezsoto, Antonio Ruizconde, E MorilloAbstract:The formation of crystalline inclusion complex of Triamterene with β-cyclodextrin (β-CD) was studied, evaluating the thermal behaviour and dispersion state of this drug in different types of binary systems. Spray-drying and co-grinding (oscillating mill) mixtures of triameterene with β-CD were prepared in 1∶1 molar ratio. The changes of crystalline properties of original (untreated) Triamterene, β-CD, and composites obtained by co-grinding and spray-drying were investigated in comparison with those produced in simple physical mixtures. The thermal behaviour of the different samples was investigated using DTA. X-ray diffraction was applied as a complementary technique. The results have been explained by formation of amorphous drug particles on spray-drying samples and co-grinding or alternatively by means of a solid dispersion formation or a combination of these two. A contamination effect by grinding media was also observed as increasing grinding time.
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thermal analysis of the system Triamterene d mannitol
Journal of Thermal Analysis and Calorimetry, 1994Co-Authors: J M Gines, M J Arias, A M Rabasco, P J SanchezsotoAbstract:Thermal analysis (DSC and HSM), and equilibrium solubility determinations were carried out to elucidate the mechanism of interaction at the solid state in the binary system Triamterene-D-mannitol. Physical mixtures (5–90% w/w Triamterene) and solid dispersions (5 up to 40% w/w Triamterene) were prepared and studied.
M J Arias - One of the best experts on this subject based on the ideXlab platform.
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thermal study of complex formation of Triamterene with β cyclodextrin by spray drying and co grinding
Journal of Thermal Analysis and Calorimetry, 1995Co-Authors: J M Gines, M J Arias, Csaba Novak, P J Sanchezsoto, Antonio Ruizconde, E MorilloAbstract:The formation of crystalline inclusion complex of Triamterene with β-cyclodextrin (β-CD) was studied, evaluating the thermal behaviour and dispersion state of this drug in different types of binary systems. Spray-drying and co-grinding (oscillating mill) mixtures of triameterene with β-CD were prepared in 1∶1 molar ratio. The changes of crystalline properties of original (untreated) Triamterene, β-CD, and composites obtained by co-grinding and spray-drying were investigated in comparison with those produced in simple physical mixtures. The thermal behaviour of the different samples was investigated using DTA. X-ray diffraction was applied as a complementary technique. The results have been explained by formation of amorphous drug particles on spray-drying samples and co-grinding or alternatively by means of a solid dispersion formation or a combination of these two. A contamination effect by grinding media was also observed as increasing grinding time.
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Improvement of the diuretic effect of Triamterene via solid dispersion technique with PEG 4000
European Journal of Drug Metabolism and Pharmacokinetics, 1994Co-Authors: M J Arias, J M Gines, J. R. Moyano, M. J. Perez-barrales, M. T. Vela, A M RabascoAbstract:The present investigation was designed and undertaken in order to substantiate further contention concerning the universality of the utilization of PEG polymers as matrix carriers. This study could then be considered an attempt to enhance the dissolution rate of Triamterene, with the subsequent enhancement in its absorption rate, via solid dispersion using PEG 4000. The approach of solid dispersions was found useful for optimizing the pharmacokinetic of Triamterene in rats.
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thermal analysis of the system Triamterene d mannitol
Journal of Thermal Analysis and Calorimetry, 1994Co-Authors: J M Gines, M J Arias, A M Rabasco, P J SanchezsotoAbstract:Thermal analysis (DSC and HSM), and equilibrium solubility determinations were carried out to elucidate the mechanism of interaction at the solid state in the binary system Triamterene-D-mannitol. Physical mixtures (5–90% w/w Triamterene) and solid dispersions (5 up to 40% w/w Triamterene) were prepared and studied.
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dissolution rate study of fresh and aging Triamterene urea solid dispersions
Drug Development and Industrial Pharmacy, 1994Co-Authors: J M Gines, M J Arias, M A Holgado, M F Arevalo, A M RabascoAbstract:Triamterene-urea solid dispersions of varying weight fractions were elaborated by the melting carrier method and their dissolution profiles compared with the pure drug and physical mixtures. The dissolution rates of Triamterene from solid dispersions were faster than the pure drug and physical mixtures.Solubility studies revealed a linear increase in the solubility of the Triamterene with the increase of urea concentration.The intrinsic dissolution rates, determined by the rotating disc method, showed linear dissolution profiles in spite of that the scanning electron microscopy examination revealed that the surfaces do not maintain constant during the dissolution process.Aging of the different preparations for one year at room temperature does not induced significant changes in their dissolution profiles.
