SSNMR characterization of new supramolecular complexes of cyclodextrin and norfloxacin polymorphs

A.K. CHATTAH; K.H. MROUE; A. RAMAMOORTHY; L.Y. PFUND; M.R. LONGHI; C. GARNERO

Rosario

Taller; Frontiers in Magnetic Resonance, from Materials to Biological Systems; 2013

Sistema Nacional de Resonancia Magnética e IBR Rosario

Two critical factors resposible for the poor and highly variable human bioavailability of some pharmaceuticals are their low permeability and solubility. On the other hand, selecting a proper polymorph and to control polymorphic transformations has a great impact in pharmaceutical and regulation issues. With these facts in mind, we have focused our work on preparing and characterizing new supramolecular systems of Norfloxacin (NOR) polymorphs B and C with BETA-cyclodextrin (BCD). The polymorphs of NOR, their physical mixtures with BCD, and the corresponding NOR:BCD complexes were investigated using a variety of spectroscopic techniques including ssNMR, PXRD, and Fourier transform infrared (FT-IR) spectroscopy. Additionally, measurement of the proton spin-lattice relaxation times (1H -T1) using 1H spin-inversion recovery experiments detected in 13C ramped-amplitude (Ramp)-CP-MAS spectra, has enabled us to gain better insights into the complex formation, as well as into the interactions among their individual components at the molecular level.