Double-edged sword: Fluoxetine and ibuprofen as development jeopardizers and apoptosis' inducers in common toad, Bufo bufo, tadpoles

Nowadays the presence of pharmaceuticals in the environment is a real problem. Ending up in aquatic environments they negatively affect non-target organisms. Considering the limited studies on the negative effects of pharmaceuticals in amphibians, a better understanding of the mechanisms underlying the sub-lethal effects of drug mixtures in wildlife is an urgent call. Representing particularly vulnerable organisms currently at risk of extinction, amphibians are perfect non-target organisms to explore the consequences of pharmaceuticals during sensitive life-stages. To address this existing research gap, the effects of two drugs, the antidepressant fluoxetine and the anti-inflammatory ibuprofen, as well as their combination has been studied. Tadpoles of Bufo bufo were exposed for seven days to two environmentally realistic concentrations of fluoxetine, ibuprofen and their mixture. The development, behavior and erythron profile were then evaluated as endpoints of exposure response. Both drugs negatively affected tadpoles' growth and development by significantly delayed their time to metamorphosis and reduced body weight. Behaviors were also impaired with a significant increase of unresponsiveness to different stimuli. Mutagenic analysis of blood revealed a significant increase in the frequency of cellular and nuclear abnormalities. Given the complexity of systems and functions affected, our work confirms the toxicological potential of fluoxetine and ibuprofen in B. bufo tadpoles by emphasizing their role as tadpole development delayers and erythrocyte apoptosis-inducers. To our knowledge, this is the first study trying to elucidate the potentially toxic effects of a mixture of an antidepressant with a non-steroidal anti-inflammatory drug using bullfrog tadpole as model organism. Both drugs interacted in impairing development and fitness in tadpoles, which might affect long-term species perpetuation and population dynamic. More in-depth research is needed to elucidate the nature of interaction and molecular mechanisms of mixed pharmaceutical compounds on non-targeted organisms.