Dynamics and interactions of ibuprofen in cyclodextrin nanosponges by solid-state NMR spectroscopy

• Published in: Beilstein journal of organic chemistry 2017-01, Vol.13 (1), p.182-194
• Main Authors: Ferro, Monica, Castiglione, Franca, Pastori, Nadia, Punta, Carlo, Melone, Lucio, Panzeri, Walter, Rossi, Barbara, Trotta, Francesco, Mele, Andrea
• Format: Article
• Language: English
• Subjects: Acetic acid; Acids; Chemistry; cross-polarization; cyclodextrin; Edetic acid; Freeze drying; Full Research Paper; Hydrogels; Ibuprofen; Magnetic resonance spectroscopy; nanosponges; NMR; Nonsteroidal anti-inflammatory drugs; Nuclear magnetic resonance; Pharmaceuticals; Polymers; Sodium; solid-state NMR; X-ray diffraction; β-Cyclodextrin
• ISSN: 1860-5397; 2195-951X; 1860-5397
• DOI: 10.3762/bjoc.13.21

Two different formulations of cyclodextrin nanosponges (CDNS), obtained by polycondensation of β-cyclodextrin with ethylenediaminetetraacetic acid dianhydride (EDTAn), were treated with aqueous solutions of ibuprofen sodium salt (IbuNa) affording hydrogels that, after lyophilisation, gave two solid CDNS-drug formulations. H fast MAS NMR and C CP-MAS NMR spectra showed that IbuNa was converted in situ into its acidic and dimeric form (IbuH) after freeze-drying. C CP-MAS NMR spectra also indicated that the structure of the nanosponge did not undergo changes upon drug loading compared to the unloaded system. However, the C NMR spectra collected under variable contact time cross-polarization (VCT-CP) conditions showed that the polymeric scaffold CDNS changed significantly its dynamic regime on passing from the empty CDNS to the drug-loaded CDNS, thus showing that the drug encapsulation can be seen as the formation of a real supramolecular aggregate rather than a conglomerate of two solid components. Finally, the structural features obtained from the different solid-state NMR approaches reported matched the information from powder X-ray diffraction profiles.