Complexation study of diclofenac with β-cyclodextrin and spectrofluorimetric determination

Abstract

The inclusional complexation between the anti-inflammatory pharmaceutical diclofenac and beta-cyclodextrin (beta-CD) was studied by potentiometry, spectrophotometry and spectrofluorimetry, in both acid and neutral pH. Guest-host 1:1 stoichiometries for the complexes in both media were determined, and their equilibrium constants were calculated. The values obtained from the different methods used are in very good agreement and are in the order of 10(3). From the analysis of the pKa value for diclofenac in both the absence and presence of beta-CD (4.84 and 4.90 respectively), it was inferred that in the inclusion complex the carboxylic group is located outside the cavity. Further structural characterization of the inclusate was carried out by means of 1H NMR spectra and AM1 semiempirical calculations. Based on the obtained results, a spectrofluorimetric method for the determination of diclofenac in the presence of beta-CD was developed in the range of 0-5 micrograms ml-1. Better limits of detection (0.03 microgram ml-1) and quantification (0.1 microgram ml-1) were obtained in this latter case with respect to those obtained in the absence of beta-CD. The method was satisfactorily applied to the quantification of diclofenac in pharmaceutical preparations.

Diclofenac-β-cyclodextrin binary systems: Physicochemical characterization and in vitro dissolution and diffusion studies

“…24 The 1 H NMR spectra obtained during this study did not show separate signals for free and complexed DCF as a consequence of the fast exchange between the free and included forms. Figure 7 shows dissolution profiles of the 2 DCF-β-CD binary systems (physical mixture and freeze-dried) in comparison with that of the pure drug.…”

Study on the Supramolecular Interaction of β‐Cyclodextrin with Gemfibrozil by Spectrofluorimetry and Its Analytical Application

“…12 The formation of the inclusion complex can alter the photochemical and photophysical properties of the guest molecules. 13 Nowadays, considerable attention has been focused on the luminescence application of the cyclodextrin. [14][15][16][17][18] Figure 2 The structure of CD oligosaccharide.…”

Determination of complex stabilities with 1,10-phenanthroline-5,6-dione as ligand for the complexation of several transition metallic cations using chemometrics methods

“…The most common experimental techniques for the determination of stability constants are potentiometry, conductometry, polarography, nuclear magnetic resonance spectroscopy, UV-Vis and fluorescence spectroscopy and calorimetry [7][8][9][10][11][12][13].…”