Complex formation of cyclodextrins with some pharmacologically active 1,2,4-thiadiazole derivatives

Abstract Previously synthesized 1,2,4-thiadiazole derivatives displayed an activity in the treatment of Alzheimer’s disease; however, these compounds are poorly soluble in aqueous solutions. Inclusion complex formation with cyclodextrins is proposed for the development of water-soluble dosage forms...
Ausführliche Beschreibung

Abstract Previously synthesized 1,2,4-thiadiazole derivatives displayed an activity in the treatment of Alzheimer’s disease; however, these compounds are poorly soluble in aqueous solutions. Inclusion complex formation with cyclodextrins is proposed for the development of water-soluble dosage forms of 1,2,4-thiadiazoles under study. To this end, binding of 1,2,4-thiadiazole derivatives with α-, β- and γ-cyclodextrins as well as with modified β-cyclodextrins was investigated by isothermal titration calorimetry, 1H NMR and UV–Vis spectroscopy in aqueous buffered solution (pH = 7.4) at 298.15 K. The detailed analysis of the thermodynamic parameters of complex formation is presented. The structure of 1,2,4-thiadiazole/cyclodextrin complexes was evaluated on the basis of 2D 1NMR (ROESY) experiments. The influence of structural factor (dimensions of macrocyclic cavity, modification of the host external surface, structure of guest molecules) on the thermodynamics and binding mode was discussed. Ausführliche Beschreibung