Single-dose pharmacokinetics of flumequine in halibut (Hippoglossus hippoglossus) and turbot (Scophthalmus maximus)

Flumequine was administered to halibut (Hippoglossus hippoglossus) and turb ot (Scophthalmus maximus) intravenously (i.v.) and orally (p.o.) at a dose of 10 mg/ kg bodyweight, and as a bath-treatment at a dose of 10 mg/L water for 2 h, using identical experimental designs. The study was performed in seawater with a salinity of 3% and a temperature of 10.3 +/- 0.4 degrees C (halibut) and 18.0 +/- 0.3 degrees C (turbot). Pharmacokinetic modelling of the data showed that flumequine had quite similar pharmacokinetic properti es in halibut and turbot. Following intravenous administration, the volumes of distribution at steady state (V-ss) were 2.99 L/kg (halibut) and 3:75 L /kg (turbot). Plasma clearances (Cl) were 0.12 L/kg (halibut) and 0.17 L/h. kg (turbot) and the elimination half-lives (t(1/2 lambda z)) were calculate d to be 32 h (halibut) and 34 h (turbot). Mean residence times (MRT) were 2 5.1 h (halibut) and 22.2 h (turbot). Following oral administration, the t(1 /2 lambda z) were 43 h (halibut) and 42 h (turbot). Maximal plasma concentr ations (t(max)) were 1.4 mg/L (halibut) and 1.9 mg/L (turbot), and were obs erved 7 h post administration in both species, The oral bioavailabilities ( F) were calculated to 56% (halibut) and 59% (turbot). Following bath admini stration maximal plasma concentrations were 0.08 mg/L (halibut) and 0.14 mg / L (turbot), and were observed 0 h (halibut) and 3 h (turbot) after the en d of the bath. The bioavailability in halibut following a 2-h bath treatmen t was 5%.