Acute and Chronic Toxicity of Ketoprofen Active Pharmaceutical Ingredient and Commercial Formulations to the Freshwater Photosynthetic Species Microcystis novacekii and Chlorella vulgaris

Ketoprofen (KET) is a non-steroidal anti-inflammatory drug frequently detected in surface waters and effluents, with the potential to impact trophic base organisms. This study evaluated the toxicity of KET, in its active pharmaceutical ingredient (API) form and in four commercial formulations (KET-1, KET-2, KET-3, and KET-4), on two freshwater species: the cyanobacterium Microcystis novacekii and the microalga Chlorella vulgaris. Cell growth assays, performed under acute (4 days) and chronic (14 days) conditions, showed that the API KET was the most toxic compound, especially for M. novacekii, with a chronic EC50 of 1.35 mg/L. The commercial formulations presented distinct toxicity profiles, suggesting the influence of excipients and synergistic or antagonistic interactions. For C. vulgaris, low acute toxicity was observed, with increased chronic effects at high concentrations and possible hormetic response at low doses. Risk quotient (RQ) calculations, based on environmental concentrations of KET, indicated low risk in surface and drinking water, but high risk in untreated hospital and wastewater treatment plant effluents, especially for M. novacekii. The results show that the complete formulation, exposure time, and target species are critical factors in the ecotoxicological risk assessment of pharmaceuticals in freshwater environments.