Supramolecular interactions between tolfenamic acid and various cyclodextrins: Effects of complexation on physicochemical and spectroscopic data
Michaleas, Sotiris G.
Antoniadou -Vyza, Ekaterini A.
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Tolfenamic acid is a non-steroidal inflammatory drug with associated gastrointestinal side-effects and problems with bioavailability. Furthermore, it is extremely insoluble in water. Tolfenamic acid was complexed with various cyclodextrins (β-CyD, HP-β-CyD, methyl-β-CyD) in order to circumvent some of these problems. During the characterization of the inclusion complexes with spectroscopic methods, significant variations in the UV and NMR spectra were observed and attributed to the supramolecular interactions between the guest and host molecules. A validated HPLC method was applied to obtain accurate measurements. The complexation process was further examined; the time needed for the completion of the complexation was determined, the binding constants of the complexes were calculated and the energetics of the system were evaluated. The solubility of tolfenamic acid was 30-fold in the presence of HP-β-CyD and twofold in the presence of methyl-β-CyD.