How toxic is the COVID-19 drug azithromycin in the presence of Posidonia oceanica? Toxicokinetics and experimental approach of meiobenthic nematodes from a metallically pristine area

The current study presents the results of an experiment carried to assess the impact of azithromycin, a COVID-19 drug, probably accumulated in marine sediments for three years, since the start of the pandemic, on benthic marine nematodes. It was explored the extent to which a common macrophyte from the Mediterranean Sea influenced the toxic impact of azithromycin on meiobenthic nematodes. Metals are known to influence toxicity of azithromycin. The nematofauna from a metallically pristine site situated in Bizerte bay, Tunisia, was exposed to two concentrations of azithromycin [i.e. 5 and 10 mu g l- 1]. In addition, two masses of the common macrophyte Posidonia oceanica [10 and 20% Dry Weight (DW)] were considered and associated with azithromycin into four possible combinations. The abundance and the taxonomic diversity of the nematode communities decreased significantly following the exposure to azithromycin, which was confirmed by the toxicokinetic data and behaving as substrate for P-glycoprotein (P-gp). The toxicity of 5 mu g l- 1 dosage of azithromycin was partially reduced at 10% DW of Posidonia and completely at 20% DW. The results showed that 5 mu g l- 1 of azithromycin can be reduced by the macrophyte P. oceanica when present in the environment at low masses as 10% DW.

Automated summary

This study assessed the impact of azithromycin, a COVID-19 drug, on benthic marine nematodes, and found that the drug may have accumulated in marine sediments for three years. The study also explored the toxic impact of azithromycin on meiobenthic nematodes in the presence of a common macrophyte from the Mediterranean Sea. The results showed that the abundance and taxonomic diversity of nematode communities were significantly decreased by azithromycin, but the toxicity could be partially reduced or completely eliminated in the presence of a low mass of the macrophyte.