Influence of temperature and ionization on self-association of theophylline in aqueous solution. Studies by proton nuclear magnetic resonance spectroscopy.

Nishijo, Juziro; Yonetani, Ikuko; Tagahara, Kiyoshi; Suzuta, Yukio; Iwamoto, Emiko

doi:10.1248/cpb.34.4451

Cited by 7 publications

(4 citation statements)

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Section: Resultssupporting

confidence: 91%

“…This shows that the hydrophobic character decreases in the following order: CAF > TPY > TBR. This hydrophobicity behavior is well supported with the observations made by Nishijo et al 48 This order is in consonance with increase in Δ tr V 2,ϕ 0 values for the three studied solutes. The solubility behavior of solutes in aqueous medium as well as in the presence of cosolute assumes a very important role in the biophysical chemistry.…”

Section: Resultssupporting

confidence: 91%

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Volumetric, Viscometric and Spectroscopic Approach to Study the Solvation Behavior of Xanthine Drugs in Aqueous Solutions of NaCl at T = 288.15–318.15 K and at p = 101.325 kPa

et al. 2016

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The densities (ρ), viscosities (η), and 1 H nuclear magnetic resonance (NMR) studies for caffeine, theophylline, and theobromine in water and in aqueous solutions of 0.10, 0.25, 0.50, 0.75, and 1.00 mol•kg −1 sodium chloride over a temperature range T = 288.15−318.15 K and at p = 101.325 kPa have been carried out using vibrating-tube digital densimeter, micro-Ubbelohde type capillary viscometer, and Bruker (AVANCE-III, HD 500 MHz) NMR spectrometer, respectively. From the density and viscosity data, apparent molar volume (V 2,ϕ ), partial molar volume at infinite dilution (V 2,ϕ 0 ), viscosity B-coefficient, corresponding transfer (Δ tr V 2,ϕ 0 and Δ tr B) and other related parameters have been calculated. The trends in transfer parameters reveal the dominance of hydrophilic−ionic interactions at lower molalities of NaCl while hydrophobic−ionic interactions at higher molalities of NaCl. The expansibilities and dB/dT data show the structurebreaking behavior of theophylline and theobromine in water and in aqueous solutions of NaCl. However, behavior of caffeine is exceptional. The increase in chemical shift (δ) values with increasing molalities of NaCl also signifies the predominance of solute−cosolute interactions over the dehydration process. The results have further been discussed and rationalized in terms of various interactions.

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Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 91%

Volumetric, Viscometric and Spectroscopic Approach to Study the Solvation Behavior of Xanthine Drugs in Aqueous Solutions of NaCl at T = 288.15–318.15 K and at p = 101.325 kPa

et al. 2016

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“…(c) Theophylline may form dimers or higher aggregates in solution (Thakkar, 1971;Guttman, 1971), and make it difficult for a growth unit to attach itself onto th~ lattice. The formation of dimers or aggregates may be temperature dependent (Nishijo, 1986).…”

Section: Growth Modelsmentioning

confidence: 99%

The kinetics of solvent-mediated phase transformations

1985

Proc. R. Soc. Lond. A

335

210

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A number of mineralogical and synthetic precipitates undergo solid to solid phase changes via a solution phase. A review of the literature reveals a lack of both experimental data and a framework for its interpretation. A model is developed, for the case of a polymorphic phase transformation, which involves the dissolution of the metastable phase and growth of nuclei of the stable phase. The concepts of dissolution and growth time scales have been introduced and it is shown that their sum is the time required for the disappearance of the metastable phase. Mechanistic insight is best obtained by measurement of the supersaturation profile rather than conversion data. It is shown that such profiles are dominated by the plateau supersaturation, which is the point at which dissolution and growth are balanced. Its value is determined by the relative surface areas of the phases and their kinetic constants. The model has been successfully used to simulate available kinetic data for the α → β polymorphic transformation in copper phthalocyanine.

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“…As it can be observed, A parameter shows higher negative values than those found for caffeine, indicating a distinct self-associative capacity with interactions between the theophylline molecules stronger than those produced between caffeine molecules, especially at 310.15 K. The B coefficient value is positive, and the values for (d B /dT = 0.06) and B/trueV20¯ are equal to those of caffeine at both temperatures, which means the structure-making character of theophylline in aqueous solution, reinforcing the previous conclusion from the analysis of the apparent molar volumes. A value of B for theophylline lower than that for caffeine is in agreement with the fact that the theophylline molecule has one less methyl group; therefore, it is more polar (less hydrophobic) than caffeine and it is likely that the structure of water is less affected by the self-association of this solute [67,68].…”

Section: Resultsmentioning

confidence: 61%

Drug Delivery Systems: Study of Inclusion Complex Formation between Methylxanthines and Cyclodextrins and Their Thermodynamic and Transport Properties

2019

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This paper presents an analysis of the molecular mechanisms involved in the formation of inclusion complexes together with some structural interpretation of drug–carrier molecule interactions in aqueous multicomponent systems comprising methylxanthines and cyclodextrins. The determination of apparent partial molar volumes ( φ V ) from experimental density measurements, both for binary and ternary aqueous solutions of cyclodextrins and methylxanthines, was performed at low concentration range to be consistent with their therapeutic uses in the drug-releasing field. The estimation of the equilibrium constant for inclusion complexes of 1:1 stoichiometry was done through the mathematical modelling of this apparent molar property. The examination of the volume changes offered information about the driving forces for the insertion of the xanthine into the cyclodextrin molecule. The analysis on the volumes of transfer, Δ φ V , c , and the viscosity B-coefficients of transfer, ΔB, for the xanthine from water to the different aqueous solutions of cyclodextrin allowed evaluating the possible interactions between aqueous solutes and/or solute–solvent interactions occurring in the solution. Mutual diffusion coefficients for binary, and ternary mixtures composed by xanthine, cyclodextrin, and water were measured with the Taylor dispersion technique. The behavior diffusion of these multicomponent systems and the coupled flows occurring in the solution were analyzed in order to understand the probable interactions between cyclodextrin–xanthine by estimating their association constants and leading to clearer insight of these systems structure. The measurements were performed at the standard (298.15 ± 0.01) K and physiological (310.15 ± 0.01) K temperatures.

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Influence of temperature and ionization on self-association of theophylline in aqueous solution. Studies by proton nuclear magnetic resonance spectroscopy.

Cited by 7 publications

References 0 publications

Volumetric, Viscometric and Spectroscopic Approach to Study the Solvation Behavior of Xanthine Drugs in Aqueous Solutions of NaCl at T = 288.15–318.15 K and at p = 101.325 kPa

Volumetric, Viscometric and Spectroscopic Approach to Study the Solvation Behavior of Xanthine Drugs in Aqueous Solutions of NaCl at T = 288.15–318.15 K and at p = 101.325 kPa

The kinetics of solvent-mediated phase transformations

Drug Delivery Systems: Study of Inclusion Complex Formation between Methylxanthines and Cyclodextrins and Their Thermodynamic and Transport Properties

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