Physicochemical characteristics of the inclusion complexes of biologically active compounds with 2-hydroxypropyl-β-cyclodextrin

Highlights: •Inclusion complexes of biologically active compounds with 2HP-β-CD were prepared. •The solubility of compounds complexing with 2HP-β-CD was improved. •Stability constants and thermodynamic parameters of complexation have been calculated. •Complex formation was confirmed by UV–vis, FTIR, DSC and XPRD methods. •The intrinsic dissolution rate of the supramolecular complexes were measured. -- Abstract: Inclusion complexation of 2-hydroxypropyl-β-cyclodextrin with biologically active compounds 2-hydroxybenzaldehyde isonicotinoylhydrazone and 2-hydroxy-3-methoxybenzaldehyde isonicotinoylhydrazone in buffer pH 7.4 solution and in solid state have been investigated. The solubility of compounds at different concentrations 2-hydroxypropyl-β-cyclodextrin was studied by phase solubility method. The profile displayed a typical A_L-type, indicating the formation of 1:1 stoichiometric inclusion complex. Solution state complexation in buffer was validated by ultra violet absorption. Stoichiometry of complex was confirmed by Job's method. The water solubility of compounds studied was significantly increased through complexation with 2-hydroxypropyl-β-cyclodextrin. Complexation stability constants and thermodynamic parameters have been calculated. It has been concluded that inclusion complexation is an exothermal and enthalpy-determined process. The solid state inclusion complex was prepared by the ball-milling method and characterized by differential scanning calorimetry, Fourier-transform infrared spectroscopy and X-ray powder diffraction. The dissolution rate of the active pharmaceutical ingredient of the supramolecular complexes were obtained.