Probing the dynamics of complexed local anesthetics via neutron scattering spectroscopy and DFT calculations

Publication date: 30 May 2017 Source:International Journal of Pharmaceutics, Volume 524, Issues 1–2 Author(s): Murillo L. Martins, Juergen Eckert, Henrik Jacobsen, Éverton C. dos Santos, Rosanna Ignazzi, Daniele Ribeiro de Araujo, Marie-Claire Bellissent-Funel, Francesca Natali, Michael Marek Koza, Aleksander Matic, Eneida de Paula, Heloisa N. Bordallo Since potential changes in the dynamics and mobility of drugs upon complexation for delivery may affect their ultimate efficacy, we have investigated the dynamics of two local anesthetic molecules, bupivacaine (BVC, C18H28N2O) and ropivacaine (RVC, C17H26N2O), in both their crystalline forms and complexed with water-soluble oligosaccharide 2-hydroxypropyl-β-cyclodextrin (HP-β-CD). The study was carried out by neutron scattering spectroscopy, along with thermal analysis, and density functional theory computation. Mean square displacements suggest that RVC may be less flexible in crystalline form than BVC, but both molecules exhibit very similar dynamics when confined in HP-β-CD. The use of vibrational analysis by density functional theory (DFT) made possible the identification of molecular modes that are most affected in both molecules by insertion into HP-β-CD, namely those of the piperidine rings and methyl groups. Nonetheless, the somewhat greater structure in the vibrational spectrum at room temperature of complexed RVC than that of BVC, suggests that the effects of complexation are more severe for the l...
Source: International Journal of Pharmaceutics - Category: Drugs & Pharmacology Source Type: research