Complexation of docetaxel with β-cyclodextrin and HP-β-cyclodextrin

Key words: 
• docetaxel /
• β-cyclodextrin /
• hydroxypropyl-β-cyclodextrin /
• complexation ratio /
• apparent complexation constant /
• thermodynamic parameter

Abstract: Objective: To study the inclusion effects of β-CD and HP-β-CD on docetaxel. Methods: The inclusion compound was prepared by the free-drying method and trituration.The measurements of the inclusion molar ratio of the host to guest molecules,apparent complexation constant,the thermodynamic 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 aqueous soluble complexes with 1-1 molar ratio.AN-type phase solubility curves were obtained.The apparent complexation constant K decreased when the temperature increased.All thermodynamic parameters of ΔG,ΔH and ΔS in the complexations gave negative values.The solubility of docetaxel complexed with β-CD was higher than that of docetaxel complexed with HP-β-CD,also the apparent complexation constant of docetaxel-β-CD was higher than that of docetaxel-HP-β-CD. Conclusion: The inclusion complex of DTX-Cyclodextrin could be formed spontaneously,and lower temperature is a benefit to the formation and the stability of the inclusion complex.The solubility and the stability constant of docetaxel complexed with β-CD is higher than that of docetaxel complexed with HP-β-CD.