Studies on the interaction of diflunisal ion with cyclodextrins using ion-selective electrode potentiometry
| Autor: | Georgia Valsami, Panayotis E. Macheras, Evangelos E. Sideris, Michael A. Koupparis |
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| Rok vydání: | 1999 |
| Předmět: |
Stereochemistry
Kinetics Analytical chemistry Pharmaceutical Science Diflunisal Inclusion compound Ion Ion selective electrode symbols.namesake chemistry.chemical_compound medicine Electrodes chemistry.chemical_classification Cyclodextrins Cyclodextrin Anti-Inflammatory Agents Non-Steroidal Temperature Cooperative binding Hydrogen-Ion Concentration Gibbs free energy chemistry Calibration Potentiometry symbols Thermodynamics Indicators and Reagents Algorithms medicine.drug |
| Zdroj: | European Journal of Pharmaceutical Sciences. 7:271-278 |
| ISSN: | 0928-0987 |
| DOI: | 10.1016/s0928-0987(98)00035-9 |
| Popis: | The interaction of diflunisal ion (DF) with beta-cyclodextrin (betaCD), gamma-cyclodextrin (gammaCD), and hydroxypropyl-beta-cyclodextrin (HPbetaCD) was studied in phosphate buffer, pH 7.4, at 5-37 degrees C and various CD concentrations using a home-made diflunisal ion-selective electrode. Typical direct binding plots and Scatchard plots were obtained with HPbetaCD. The Scatchard model for one class of binding sites was used for the estimation of binding parameters for the DF/HPbetaCD interaction. The estimates for n (number of binding sites per CD molecule) were in all cases very close to unity, indicating 1:1 complexation. The association constant (K) estimates decrease with increasing temperature. Sigmoidal direct binding plots and concave-downwards Scatchard plots were obtained with various betaCD or gammaCD concentrations. The Hill model was used for the estimation of the binding parameters for the DF/betaCD and DF/gammaCD interactions. Both the Hill coefficients and the binding constants were markedly dependent on the CD concentration. These findings indicate the cooperative character of DF/betaCD and DF/gammaCD interactions. The free energy change, DeltaG, and the thermodynamic parameters, DeltaH and DeltaS, were estimated for each of the interactions studied using the Van't Hoff equation. |
| Databáze: | OpenAIRE |
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