engleski

Evaluation of antibiotic cefdinir degradation under sunlight irradiation

INTRODUCTION Over the last decades, the presence of pharmaceuticals in the environment is well-known problem in terms of human health and the environment (Gavrilescu et al., 2015). Moreover, the rapid emergence of resistant bacteria worldwide (Ventola, 2015) can be connected to the fact that antibiotics have been widely used. When pharmaceuticals enter the aquatic environment, one of the most important pathways of their degradation are photochemical processes. It is worth noting that direct and indirect photolysis can have high impact on the environmental half-lives of pharmaceutical compounds. Due to the structural moieties of cefdinir, it is presumed that it absorbs light in the environmentally relevant range (300 ̶ 800 nm). OBJECTIVES In this work the focus was to examine the photolytic fate and behaviour of cefdinir which belongs to a broad spectrum and thirdgeneration of cephalosporin antibioticsused for the treatment of upper and lower respiratory tract infections and urinary tract infections (Abou-Taleb et al., 2016). METHODS The photolysis experiments were carried out in Suntest CPS+ simulator (Atlas, Germany) equipped with a xenon lamp and temperature sensor used as the source of artificial sunlight in the wavelength range of 300̶800 nm. In all experiments irradiation was maintained constant at 500 W m−2, while the reaction temperature was kept at (25 ± 2) °C. Cefdinir solutions were irradiated in quartz vessels. Dark control experiments were performed under the same conditions to those described above, except that the vessels were wrapped in aluminium foil. At regular time intervals aliquots (0.5 mL) of cefdinir solution were withdrawn and analyzed by HPLC-DAD. RESULTS Cefdinir was irradiated under simulated sunlight in different water matrices in order to investigate influence of both direct and indirect photolysis. It was found out that it undergo photolysis which can be seen in Figure 1., in the case of river water and synthetic wastewater. Also, influence of pH-value was investigated since it was found that it plays an important role on photolysis of many pharmaceuticals(Li et al., 2018). Degradation rate constant were very similar at all investigated pH-values with a little bit faster degradation in basic conditions. In all conducted experiments degradation of cefdinir followed first order kinetics with half-lives around 20 minutes. CONCLUSION On the basis of relatively quick degradation of cefdinir it can be concluded that photolysis might be an important process of reducing its concentration in the environment. Hence, the results obtained in this study could increase knowledge of the understanding of cefdinir fate and behaviour in the environment

pharmaceuticals, cefdinir, photolysis, aqueous environment

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