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Studies on the interaction of diflunisal ion with cyclodextrins using ion-selective electrode potentiometry. 1999

E E Sideris, and G N Valsami, and M A Koupparis, and P E Macheras
Laboratory of Biopharmaceutics and Pharmacokinetics, Department of Pharmacy, University of Athens, Panepistimiopolis, Athens 15771, Greece.

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.

UI MeSH Term Description Entries
D007202 Indicators and Reagents Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499) Indicator,Reagent,Reagents,Indicators,Reagents and Indicators
D007700 Kinetics The rate dynamics in chemical or physical systems.
D011199 Potentiometry Solution titration in which the end point is read from the electrode-potential variations with the concentrations of potential determining ions. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
D002138 Calibration Determination, by measurement or comparison with a standard, of the correct value of each scale reading on a meter or other measuring instrument; or determination of the settings of a control device that correspond to particular values of voltage, current, frequency or other output. Calibrations
D003505 Cyclodextrins A homologous group of cyclic GLUCANS consisting of alpha-1,4 bound glucose units obtained by the action of cyclodextrin glucanotransferase on starch or similar substrates. The enzyme is produced by certain species of Bacillus. Cyclodextrins form inclusion complexes with a wide variety of substances. Cycloamylose,Cyclodextrin,Cyclodextrin Derivatives,Cyclomaltooligosaccharides,Derivatives, Cyclodextrin
D004061 Diflunisal A salicylate derivative and anti-inflammatory analgesic with actions and side effects similar to those of ASPIRIN. Apo-Diflunisal,Dolobid,Dolobis,Dolocid,MK-647,Novo-Diflunisal,Nu-Diflunisal,Apo Diflunisal,ApoDiflunisal,MK 647,MK647,Novo Diflunisal,NovoDiflunisal,Nu Diflunisal,NuDiflunisal
D004566 Electrodes Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum. Anode,Anode Materials,Cathode,Cathode Materials,Anode Material,Anodes,Cathode Material,Cathodes,Electrode,Material, Anode,Material, Cathode
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000465 Algorithms A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task. Algorithm
D000894 Anti-Inflammatory Agents, Non-Steroidal Anti-inflammatory agents that are non-steroidal in nature. In addition to anti-inflammatory actions, they have analgesic, antipyretic, and platelet-inhibitory actions. They act by blocking the synthesis of prostaglandins by inhibiting cyclooxygenase, which converts arachidonic acid to cyclic endoperoxides, precursors of prostaglandins. Inhibition of prostaglandin synthesis accounts for their analgesic, antipyretic, and platelet-inhibitory actions; other mechanisms may contribute to their anti-inflammatory effects. Analgesics, Anti-Inflammatory,Aspirin-Like Agent,Aspirin-Like Agents,NSAID,Non-Steroidal Anti-Inflammatory Agent,Non-Steroidal Anti-Inflammatory Agents,Nonsteroidal Anti-Inflammatory Agent,Anti Inflammatory Agents, Nonsteroidal,Antiinflammatory Agents, Non Steroidal,Antiinflammatory Agents, Nonsteroidal,NSAIDs,Nonsteroidal Anti-Inflammatory Agents,Agent, Aspirin-Like,Agent, Non-Steroidal Anti-Inflammatory,Agent, Nonsteroidal Anti-Inflammatory,Anti-Inflammatory Agent, Non-Steroidal,Anti-Inflammatory Agent, Nonsteroidal,Anti-Inflammatory Analgesics,Aspirin Like Agent,Aspirin Like Agents,Non Steroidal Anti Inflammatory Agent,Non Steroidal Anti Inflammatory Agents,Nonsteroidal Anti Inflammatory Agent,Nonsteroidal Anti Inflammatory Agents,Nonsteroidal Antiinflammatory Agents

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