“Study on the host-guest interaction between different β-cyclodextrin derivatives and model drug ibuprofen"

Aim The aim of this work was to investigate if and to which extent, the efficiency of complexation between model drug ibuprofen and β-CDs could be influenced by modification in substituent groups bonded at the sucrose ring. Methods Solutions of commercial β-cyclodextrin and derivatives, (namely hydroxypropyl-β-cyclodextrin with two different degrees of substitution and methyl-β-cyclodextrin) (Roquette Freres, Lesterm, France) as well as ibuprofen solution were prepared in isotonic and isohydric phosphate buffer. For the evaluation of the efficiency of complexation between the different β-CD derivatives and ibuprofen isothermal titration calorimetry was employed (Thermo Metric Lab AB, Järfälla, Sweden). 1H-NMR was used in order to investigate the nature of the interaction between some of the different β-CD derivatives and drug molecules. Results and discussions ITC analysis of the complexation processes shows that each type of beta-cyclodextrin own its characteristic value of enthalpy and equilibrium constant of complexation with ibuprofen. 1H-NMR studies evidenced that this thermodynamic differences are due to specific three-dimensional conformations of each type of complex β-CD-ibuprofen. Conclusion It can be hypothesized that bigger is the sterical hindrance of the substituent group, lower is the dept that drug molecule can reach in the sucrose cavity and consequently lower will be the stability of the complex.