The presence of drugs in the environment is an emerging issue in the scientific community. It has been shown that these substances are active chemicals that consequently affect aquatic organisms and, finally, humans as end users. To evaluate the toxicity of these compounds and how they affect the environment, it is important to perform systematic ecotoxicological and physicochemical studies. The best way to address this problem is to conduct studies on different aquatic trophic levels. In this work, an ecotoxicological study of six drugs (anhydrous caffeine, diphenhydramine hydrochloride, gentamicin sulphate, lidocaine hydrochloride, tobramycin sulphate and enalapril maleate) that used three aquatic biological models (Raphidocelis subcapitata, Aliivibrio fischeri and Daphnia magna) was performed. Additionally, the concentration of chlorophyll in the algae R. subcapitata was measured. Furthermore, EC50 values were analysed using the Passino and Smith classification (PSC) method, which categorized the compounds as toxic or relatively toxic. All of the studied drugs showed clear concentration-dependent toxic effects. The toxicity of the chemicals depended on the biological model studied, with Raphidocelis subcapitata being the most sensitive species and Aliivibrio fischeri being the least sensitive. The results indicate that the most toxic compound, for all the studied biological models, was diphenhydramine hydrochloride. Graphical abstract.
Keywords: Aliivibrio fischeri; Daphnia magna; Dose-response; Pharmaceuticals; Raphidocelis subcapitata.