RESUMO
Glucocorticoids are widely used to treat a variety of diseases. Consequently, these compounds have been found in water and wastewater matrix. Despite studies have proven its toxicity, just a few works investigate techniques to degrade and mineralize them. To solve this issue, this work presents the degradation and mineralization of prednisone (PRED) by electrochemical advanced oxidation (EAO) using a boron-doped diamond supported on niobium (Nb/BDD) anode in synthetic and real wastewater. Cyclic voltammetry (CV) was performed to investigate the PRED oxidation mechanisms. CV suggest that PRED will be oxidized via HO⢠and other oxidants generated from the ions present in the liquid matrix (S2O82-, SO4â¢-, HClO, ClO- etc.). Different EAO conditions as initial pH (3, 7 and 11) and applied current densities (5, 10 and 20 mA cm-2) were evaluated. The best result was obtained at alkaline pH (11) and a current density of 20 mA cm-2, achieving 78% of degradation and 42% of mineralization. Using the best conditions, the EAO was applied as a polishing treatment stage to remove PRED from a biological pre-treated municipal wastewater spiked with PRED. The results indicate that EAO applied in the real matrix provides better results than the synthetic solution, probably associated with the presence of ions that can be electrochemically converted into oxidant species, resulting in higher kinetic constant, mineralization current efficiency and lower energetic consumption. Therefore, the EAO process without the addition of chemicals has proven to be an effective alternative as a tertiary treatment of municipal wastewater contaminated with PRED.
Assuntos
Nióbio , Prednisona , Poluentes Químicos da Água , Boro/química , Diamante/química , Eletrodos , Cinética , Modelos Químicos , Nióbio/química , Oxidantes , Oxirredução , Prednisona/química , Águas Residuárias/química , Água/química , Poluentes Químicos da Água/químicaRESUMO
Prednisone is considered the glucocorticoid of choice for anti-inflammatory and immunosuppressant effects. However, its very low aqueous solubility can compromise oral bioavailability. Changes in the dissolution of a prednisone-PEG 6000 solid dispersion into capsule were investigated by addition of pregelatinized starch. Physical state of prednisone:PEG 6000 was analyzed by X-ray diffractometry, and scanning electron microscopy. Capsule formulations containing prednisone-PEG 6000 and pregelatinized starch showed superior dissolution properties (> 95% in 60 min) when compared with reference capsules without disintegrant (< 45% in 60 min). Water uptake and disintegration time were directly correlated with pregelatinized starch amount. The morphology of prednisone-PEG 6000 particles with disintegrant was analyzed by SEM, showing a novel surface structure. Thus, solid dispersions of a poorly water soluble drug combined with a disintegrant were confirmed as a valid approach to the improvement of drug dissolution.
Assuntos
Portadores de Fármacos/química , Glucocorticoides/administração & dosagem , Polietilenoglicóis/química , Prednisona/administração & dosagem , Disponibilidade Biológica , Cápsulas , Química Farmacêutica , Excipientes/química , Géis , Glucocorticoides/química , Glucocorticoides/farmacocinética , Microscopia Eletrônica de Varredura , Prednisona/química , Prednisona/farmacocinética , Solubilidade , Amido/química , Fatores de Tempo , Água/química , Difração de Raios XRESUMO
The aim of the current study was to design oral fast-release polymeric tablets of prednisone and to optimize the drug dissolution profile by modifying the carrier concentration. Solid dispersions were prepared by the solvent evaporation method at different drug:polymer ratios (wt/wt). The physical state and drug:carrier interactions were analyzed by X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. The dissolution rate of prednisone from solid dispersions was markedly enhanced by increasing the polymer concentration. The tablets were prepared from solid dispersion systems using polyethylene glycol (PEG) 6000 as a carrier at low and high concentration. The results showed that PEG 6000-based tablets exhibited a significantly higher prednisone dissolution (80% within 30 minutes) than did conventional tablets prepared without PEG 6000 (<25% within 30 minutes). In addition, the good disintegration and very good dissolution performance of the developed tablets without the addition of superdisintegrant highlighted the suitability of these formulated dosage forms. The stability studies performed in normal and accelerated conditions during 12 months showed that prednisone exhibited high stability in PEG 6000 solid dispersion powders and tablets. The X-ray diffraction showed that the degree of crystallinity of prednisone in solid dispersions decreased when the ratio of the polymer increased, suggesting that the drug is present inside the samples in different physical states. The Fourier transform infrared spectroscopic studies showed the stability of prednisone and the absence of well-defined drug:polymer interactions. Scanning electron microscopy images showed a novel morphology of the dispersed systems in comparison with the pure components.
Assuntos
Portadores de Fármacos , Glucocorticoides/química , Polietilenoglicóis/química , Prednisona/química , Química Farmacêutica , Cristalografia por Raios X , Composição de Medicamentos , Estabilidade de Medicamentos , Cinética , Microscopia Eletrônica de Varredura , Difração de Pó , Reprodutibilidade dos Testes , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Comprimidos , Tecnologia Farmacêutica/métodosRESUMO
The title compound, C(22)H(28)O(5), is a commercial therapeutic agent of the steroid class. Both independent molecules in the asymmetric unit have six-membered A rings that are planar, while the B and C rings adopt normal chair conformations. The five-membered D ring is in a 13beta,14alpha-half-chair conformation, and the B/C and C/D ring junctions are in trans positions. Cohesion in the crystal is provided by O-H.O hydrogen bonds, which generate chains of molecules that are organized in a plane that lies along the crystallographic b axis.