Complexation of ketoprofen with hydroxylpropyl-β-cyclodextrin

Aim: To prepare and identify the ketoprofen (KPF)-hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex, and to investigate the complexation of KPF with HP-β-CD in aqueous solutions, inclusion molar ratio of the host to the guest molecules and change of thermodynamic parameters during the complexation process. Methods: The inclusion compound was prepared by the stirring method. The measurements of the inclusion molar ratio of the host to guest molecules, apparent complexation constant, the thermodynamics parameters and the identication of the inclusion complex were carried out by the methods such as continuous variation method, UV absorption spectroscopy, phase solubility diagram, differential scanning calorimeter(DSC) and infrared spectra(IR) methods, respectively. Results: The continuous variation method suggested the formation of a aqueous soluble complex with 1:2 molar ratio. An A_N-type phase solubility curve was obtained. The apparent complexation constant K_c decreased when the temperature increased. The change in the thermodynamic parameters suggested that the complexation could proceed spontaneously along with the release of heat and the decrease of entropy. Conclusion: The inclusion complex of KPF-HP-β-CD could be formed spontaneously, and lower temperature is a benefit to the formation and the stability of the inclusion complex. Hence, the solubility and stability of KPF in aqueous solution increase.