Non-Inclusion Complexation of Peracetylated β-Cyclodextrin with Ibuprofen in Supercritical Carbon Dioxide

[Display omitted] •A complex of ibuprofen and peracetylated β-cyclodextrin was formed in scCO2.•Spectroscopic analyses showed that the complex is not formed by inclusion.•The non-inclusion was attributed to the self-closure of this cyclodextrin in scCO2.•The ibuprofen release was retarded but still immediate. The complexation behavior of peracetylated β-cyclodextrin (PA-β-CD) in supercritical carbon dioxide (scCO2) was studied using ibuprofen as a model compound. The complex was studied by differential scanning calorimetry, infrared, raman and nuclear magnetic resonance spectroscopy, scanning electron microscopy and dissolution study. Differential scanning calorimetry showed that ibuprofen loses its crystalline form, evidencing the complexation at molecular level, which was confirmed by scanning electron microscopy, infrared and raman. Nuclear magnetic resonance spectroscopy showed shift of peaks for ibuprofen and, for PA-β-CD, it showed changes in coupling constants for H1 and H6’ and did not show shifts of peaks for H3 and H5, but for H6’, showing that the complexation occurs, but not by inclusion; it also showed that the conformation of PA-β-CD is compatible to the one it assumes in scCO2. Moreover, dissolution study showed that this kind of complex can be used for controlled drug release.