Acute toxicity of tadalafil based formulation in Artemia: bioassay response and concentration verification

Authors: Luca Szelpal, Carolina Duarte, Jacqueline Joosten, Ines Oliveira and Caio Cesar Ribeiro

Affiliations: ECHO - Ecotoxicology and Chemical Oceanography Group, Centre of Marine Sciences (CCMAR), University of Algarve, Faro, Portugal.

Abstract: Pharmaceutical residues enter aquatic environments, but formulation ingredients and limited solubility complicate hazard assessment. We assessed the acute effects of a tadalafil based pharmaceutical formulation on Artemia sp. in two concentration series, with four replicates per concentration, and used absorbance at 285 nm for preliminary concentration verification. In the first series, mortality remained low from 0 to 20 mg L-1 and reached 20 individuals across replicates at 200 mg L-1 (recorded NOEC: 20 mg L-1; LOEC: 200 mg L-1). In the second series, total mortality increased from 11 individuals at 150 mg L-1 to 38 at 250 mg L-1; the spreadsheet reports an LC50 of 221.6 mg L-1 and NOEC/LOEC values of 150/250 mg L-1. UV calibration estimated 196.1 mg L-1 in a nominal 200 mg L-1 solution. These preliminary results indicate acute effects at the upper test concentrations and demonstrate the value of pairing a rapid Artemia assay with analytical checking. Since the tested material was a pharmaceutical formulation, effects cannot be attributed to tadalafil alone. This small scale workflow can help prioritise pharmaceutical products for further aquatic testing.

Keywords: tadalafil, Artemia, pharmaceutical formulation, acute toxicity, UV spectrophotometry