Interactions of nabumetone with γ-cyclodextrin studied by fluorescence measurements

The inclusion of the anti-inflammatory drug, Nabumetone (NAB), in gamma-cyclodextrin (gamma-CD) was studied by fluorescence measurements. The emission fluorescence spectrum, of NAB reveals a maximum whose intensity increases with the different gamma-CD's growing concentrations. The stoichiometery (1:1) and binding constants of the complexes at 15, 25, 35, and 45 degrees C were extracted from the analysis of the emission spectra of NAB. The thermodynamic parameters Delta H degrees and Delta S degrees for the formation of the complex were calculated from the temperature dependence of the binding constants and compared with previous results for similar complexes of NAB with alpha- and beta-CDs. The location of NAB in the complex was determined using the fluorescence quenching method. Our results indicate that NAB is completely penetrated into the cavity of gamma-CD.