Structure determination of fexofenadine-α-cyclodextrin complex by quantitative 2D ROESY analysis and molecular mechanics studies.

Complexation of fexofenadine with α-cyclodextrin in aqueous medium was studied. The stoichiometry of the resulting inclusion complex was determined by (1) H NMR titration data. 2D ROESY data provided the evidence of formation of the complex by entry of the phenyl ring into the α-cyclodextrin cavity probably from wider opening. Determination of relative peak intensities of intermolecular cross-peaks for the most stable complexes obtained by molecular mechanics (MM2) studies and from 2D ROESY spectral data confirmed the presence of only one complex in solution that has been fully characterized.