PROTON NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY STUDIES OF THE INCLUSION COMPLEX OF PIROXICAM WITH BETA-CYCLODEXTRIN

Proton nuclear magnetic resonance spectroscopy showed that piroxicam sodium salt forms an inclusion complex with beta-cyclodextrin in aqueous solution. The 1:1 stoichiometry of the complex was determined by the continuous variation method. Significant nuclear Overhauser effects were observed between the inner protons of beta-cyclodextrin and protons of both the aromatic rings of piroxicam sodium salt, a result indicating that two isomeric 1:1 complexes must be present in solution within the range of concentrations investigated. The overall association constant was 113 M at 298 K. At concentrations less than 1.0 X 10(-3) M, the complex is completely dissociated.