Pharmacokinetics and residue depletion of erythromycin in gilthead sea bream Sparus aurata L. after oral administration

Erythromycin (ERY) is an antibiotic effective against Streptococcus iniae, a microorganism responsible for significant losses in aquaculture. No data are available on the pharmacokinetics and residue depletion of ERY in sea bream. The aim of this study was thus to evaluate the pharmacokinetics of ERY in this species after a single oral administration at 75 mg kg^-1 b.w. and to assess its residue depletion from tissues after prolonged treatment for 10 days. ERY was rapidly absorbed in sea bream (C<inf>max</inf> = 10.04 μg g^-1 and T<inf>max</inf>=1 h), with a half-life of 9.35 h and an AUC<inf>0-24</inf> of 56.81 (h μg mL^-1). The data obtained and the evaluation of pharmacokinetic/pharmacodynamic parameters allowed us to hypothesize that dosage used in this study should be effective against S. iniae. A rapid reduction in erythromycin concentrations was observed in tissues, with the drug being detectable only during the first day post-treatment. In Europe, the use of ERY in aquaculture is allowed by off-label prescription with a withdrawal time of 500 °C day^-1. The absence of ERY residues in tissues already at 24 h post-treatment suggests that ERY in sea bream should not pose human food safety issues.