Enhancing the dissolution of hydrophobic guests using solid state inclusion complexation: characterization and in vitro evaluation

The objectives of the present investigation were to prepare and characterize solid inclusion complexes of Etodolac (ETD) with β-cyclodextrin (β-CD) in order to study the effect of complexation on the dissolution rate of ETD, a hydrophobic guest molecule. Phase solubility curve was classified as a typical A_L-type for the cyclodextrins (CD’s), showing that soluble complex was formed. The inclusion complexes in the molar ratio of 1:1 and 1:2 (β-CD–ETD) were prepared by various methods such as kneading, co-evaporation and in molar ratio of 1:1 by spray dried technique respectively. The molecular behaviors of ETD in all samples were characterized by nuclear magnetic resonance (NMR) spectroscopy, fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) studies and Scanning Electron microscopy (SEM) analysis. The results of these studies indicated that complexes prepared by kneading, co-evaporation and spray drying techniques showed inclusion of the ETD molecule into the CD’s cavities. The highest improvement in in vitro dissolution profiles was observed in complexes prepared with spray dried technique. Mean in vitro dissolution time indicated significant difference between the release profiles of ETD from complexes and physical mixtures and from pure ETD.