Preparação, caracterização e estudo de dissociação do naproxeno em uma matriz de quitosana

Abstract

Studies were carried out to optimize the reaction conditions to obtain a naproxen (NAP) salt (QN) and the chitosan biopolymer (QP). This salt (QN) was used for the study of antiinflammatory dissociation equilibrium. For this, the best conditions were studied in relation to the parameters reaction time, reaction temperature and molar ratio of the reactants. The products were characterized by nuclear magnetic resonance NMR of hydrogen 1 H and carbon 13 C, Fourier transform infrared vibration spectroscopy, FTIR, ultraviolet-visible electronic spectroscopy in the diffuse reflectance, UV-vis, diffraction (XRD) and thermoanalytical techniques: thermogravimetry and differential thermal analysis simultaneous (TG/DTA) and differential scanning calorimetry (DSC). In addition, the evolution of gases by thermogravimetry coupled to spectrometer FTIR (TG-FTIR) was studied. It was found that the higher salt yield was obtained under the following reaction conditions: 24 hours, temperature of 60 ° C and molar ratio of 1 mol of QP to 1.05 mol of NAP. This reaction product was called QN1. In this case, when calculating the degree of substitution (GS) by the 13 C NMR technique, a GS of 19.1% was observed, suggesting a neutralization of the NH2 group bound to the C2 of the biopolymer with the COOH group present in the drug. In the FTIR spectra were observed bands corresponding to the formation of a product different than QP and NAP, corroborating with the hypothesis of QN1 salt formation. In the UV-vis spectrum the three bands were observed for the absorption of the chromophore groups present in the salt. In the diffractograms, there was a peak in the region of ~22θ in QN1, which was already observed as a shoulder in QP, but there was an increase, in addition, changes in the index of crystallinity of chitosan, suggested modifications in its semicrystalline structure after reaction with the NAP. The TG / DTG / DTA curves showed changes in the thermal behavior of QN1 in relation to QP, showing that the modification leads to changes in the thermal behavior and suggest the presence of NAP in the biopolymer matrix. The characterization confirmed the hypothesis of salt formation, QN1, because there were modifications in the intervals of mass loss, as well as, by the ratio between the third and second loss of mass, a stability gain can be verified. In order to improve the NAP-QP interaction capacity, the chitosan chains were crosslinked with epichlorohydrin. However, the reaction had a lower yield when compared to the uncrosslinked salt. It was verified by the different characterization techniques, mainly by 13 C NMR that, instead of organizing and leaving the amino groups even more susceptible to reaction, the chitosan structure was organized in a way that there was less interaction with the drug. Therefore, for the salts QN1 and QPEPIN1 the study of the equilibrium of dissociation by HPLC, at pH 2,00 and 7,00, was carried out, simulating conditions of the intestine and stomach, in order to verify their profile of dissociation and behavior...

Capacidade erro-zero de canais quânticos e estados puros

“…Finalmente serão enunciados aqui alguns resultados com relação à capacidade erro-zero de produtos tensoriais de canais quânticos. As demonstrações irão aparecer na versão completa deste artigo [11].…”