Tissue distribution and depletion of sarafloxacin hydrochloride after in feed administration in gilthead seabream (Sparus aurata L.)

Tissue distribution and depletion of sarafloxacin was studied in gilthead scabream, under experimental field conditions at 25 and 18 degreesC, after in-feed administration of sarafloxacin hydrochloride for 5 days (10 mg/kg body weight/day). Ten fish per sampling point were examined during and after treatment. Muscle plus skin (n = 10), liver, kidney and vertebra (pooled) were collected and analyzed by HPLC. Sarafloxacin concentrations in these tissues increased during the medication period, and then decreased rapidly. The highest sarafloxacin concentrations were recorded in liver (335.2 and 49.8 mug/g at 25 and 18 degreesC, respectively). In muscle plus skin, sarafloxacin concentrations were 193.0 and 42.0 mug/kg at 25 and 18 degreesC, respectively. Sarafloxacin residues were eliminated rapidly; at 36 It post treatment, the levels in muscle plus skin were 10.2 and 8.5 mug/kg at 25 and 18 degreesC, respectively. Elimination half-lives (t(1/2)) were 17.8 and 32.5 h at 25 and 18 degreesC, respectively. Withdrawal period for the Maximum Residue Limit (MRL) of 30 mug/kg sarafloxacin in muscle plus skin (95% tolerance limit) at 25 degreesC was 42.2 h. The slow elimination from vertebra, relative to other tissues, suggests that vertebra behaves as a reservoir in gilthead seabream. (C) 2003 Elsevier Science B.V. All rights reserved.