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Enantiomer stability and combined toxicity of duloxetine and econazole on Daphnia magna using real concentrations determined by capillary electrophoresis

Valimaña-Traverso, Jesús, Amariei, Georgiana, Boltes, Karina, García, Maria Ángeles, Marina, Maria Luisa
The Science of the total environment 2019 v.670 pp. 770-778
Daphnia magna, capillary electrophoresis, drug toxicity, drugs, ecotoxicology, enantiomers, environmental factors, exposure duration, fluorescence, oxidative stress, synergism
Enantiomer stability was investigated in this work for the first time for duloxetine and econazole in individual solutions and their mixtures under the standardized ecotoxicity test experimental conditions for Daphnia magna and abiotic conditions. Real (and not nominal) enantiomer concentrations were employed for calculations since their determination was achieved by Capillary Electrophoresis. Relevant differences were found in stability profiles for both drugs in any case. Toxicity was evaluated for the first time in this work for mixtures of duloxetine and econazole on Daphnia magna. Dose-effect parameters were calculated at different exposure times (24, 48, and 72 h) showing a significant inhibition of daphnids mobility when increasing the incubation time. Combination index values enabled to obtain the type and level of interaction of drugs with the organism. A strong synergism was observed at 48 h exposure time and any effect level, which demonstrated the high toxicity of the drug mixture compared with the individual drug solutions. These results were corroborated when evaluating the oxidative stress using fluorescence images.