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Zughul, Mohammad B.; Badwan, Adnan A.

doi:10.1023/a:1007965424219

Cited by 34 publications

(2 citation statements)

References 10 publications

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“…PS diagrams are constructed by measuring the total solubility of a fixed amount of solid substrate ( S, in this work DX) in a medium containing increasing amounts of solubilizer or ligand ( L , in this work CD). The theoretical framework for the various types of PS diagrams were laid out by Higuchi and Connors in 1965 and later developed for several special cases of B S -type PS diagrams. − The interested reader is referred to these references for details; the present text only highlights the main points.…”

Section: Theoretical Backgroundmentioning

confidence: 81%

Drug Solubilization by Mixtures of Cyclodextrins: Additive and Synergistic Effects

2019

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Cyclodextrins are popular drug solubilizers, but the use of the natural cyclodextrins is hampered by their tendency to co-precipitate with the drug. To understand and overcome such problems, we have studied the solubility of dexamethasone in the presence of natural β-cyclodextrin and γcyclodextrin, individually and in various combinations. Equilibrium models of the phase-solubility diagrams with individual cyclodextrins revealed that dexamethasone was solubilized as 1:1 complexes, but formation of insoluble higher-order complexes set an upper limit to the concentration of solubilized dexamethasone. This limit could be raised from 8 mM to 17 mM by using combinations of the two cyclodextrins, as their solubilizing properties were additive in some regions of the phase-solubility diagram and synergistic in other regions. The additive effects arise from the additivity of solubilities-same phenomenon contributes to the good solubilizing properties of many modified cyclodextrins. The synergistic effects, however, could not be explained. The results open up for an increased use of the natural cyclodextrins as an improved alternative to modified cyclodextrins.

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Section: Theoretical Backgroundmentioning

confidence: 81%

Drug Solubilization by Mixtures of Cyclodextrins: Additive and Synergistic Effects

2019

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“…Analysis of the PSDs was performed according to an early reported rigorous procedure to obtain estimates of the IRB/CD complex formation constants. 22,23 As a substrate (S), neutral, protonated, or deprotonated IRB may form soluble 1:1 (SL) and 1:2 (SL 2 ) complexes with different CD ligands (L). The equilibria involved in complex formation and the corresponding complex formation constants of SL and SL 2 complexes defined as K 11 and K 12 are given by:…”

Section: Phase-solubility Diagramsmentioning

confidence: 99%

Effect of pH on the complexation of irbesartan with -, hydroxypropyl- -, and -cyclodextrin: solubility enhancement and physicochemical characterization

Yousef¹

2018

Turk J Chem

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The affinity of irbesartan (IRB) to form inclusion complexes with β-cyclodextrin (β-CD), hydroxypropylβ-cyclodextrin (HPβ-CD), and γ-cyclodextrin (γ-CD) was investigated in aqueous buffered solutions at pH 1.7, 4.1, and 7.0. Analysis of the UV absorption-pH profiles revealed that IRB has two p Ka values: p Ka1 = 3.60 (imidazolinone ring moiety) and p Ka2 = 4.70 (tetrazole moiety). In the presence of 5.0 mmol L −1 β-CD, the tetrazole moiety became more acidic, indicating its inclusion within the β-CD cavity. Phase-solubility diagrams (PSDs) were obtained for IRB in aqueous buffered solutions of β-CD, HPβ-CD, and γ-CD at pH 4.1 (zwitterionic IRB), pH 1.7 (protonated IRB), and pH 7.0 (deprotonated IRB). Rigorous nonlinear regression analysis of IRB/CD PSDs at pH 4.1, where IRB is poorly soluble, yielded estimates of complex formation constants (K11) that followed the decreasing order of HPβ-CD > γ-CD > β-CD. The highest solubility enhancement of IRB was achieved by complexation with HPβ-CD at pH 4.1. The formation of the IRB/ β-CD inclusion complex in solution and in the solid state has been proven through NMR, DSC, FT-IR, and XRD studies. Analysis of 1 H and 13 C-NMR spectra indicated the inclusion of the tetrazole-biphenyl moiety within the β-CD cavity.

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Measuring Binding Constants of Cyclodextrin Inclusion Compounds

Landy¹

2018

Environmental Chemistry for a Sustainable World

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Cited by 34 publications

References 10 publications

Drug Solubilization by Mixtures of Cyclodextrins: Additive and Synergistic Effects

Drug Solubilization by Mixtures of Cyclodextrins: Additive and Synergistic Effects

Effect of pH on the complexation of irbesartan with -, hydroxypropyl- -, and -cyclodextrin: solubility enhancement and physicochemical characterization

Measuring Binding Constants of Cyclodextrin Inclusion Compounds

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