Concentrations in plasma and selected tissues of marbofloxacin after oral and intravenous administration in Bilgorajska geese (Anser anser domesticus)

Aims: To determine the pharmacokinetics and tissue depletion of 2 mg/kg marbofloxacin (MBX) in Bilgorajska geese (Anser anser domesticus) after I/V and oral administration, to calculate the daily dose from experimental data and to compare it with that calculated by allometric scaling.Methods: Eight clinically normal female Bilgorajska geese were used in a three-phase study with a 3-week wash-out period between phases. In the first phase birds received I/V administration of 2 mg/kg MBX; the same dose was given orally in the second and third phases. Blood samples were collected between 0 minutes and 48 hours in the first and second phases, and samples of liver, kidney, lung, muscle and heart were collected following slaughter of birds between 6 and 48 hours in the third phase. Concentrations of MBX in plasma and tissues were analysed using HPLC. Two additional birds served as controls. The optimal dose was calculated based on a minimal inhibitory concentration (MIC) of 0.125 μg⁄mL using the observed clearance, or using clearance calculated by allometric scaling.Results: Concentrations of MBX in plasma were detectable up to 24 hours following both I/V and oral administration. Mean oral bioavailability was 26.5 (SD 7.7)%. Concentrations of MBX in all tissues were highest at 6 hours and decreased constantly up to 34 hours. The mean optimal daily dose for oral administration of MBX, calculated using the observed clearance was 10.36 (SD 2.18) mg/kg, and using predicted clearance was 5.54 (SD 0.14) mg/kg. The preliminary withdrawal time for a maximum residue limit of 0.15 mg/kg calculated for muscle was 38.4 hours, heart 33.6 hours, kidney 48.3 hours, lung 47.7 hours and liver 49.3 hours.Conclusion and Clinical Relevance: There was insufficient evidence to recommend MBX orally administered to geese at a daily dose of 2 mg⁄kg for treatment of bacteria with an MIC of 0.125 μg/mL. Further pharmacokinetic/pharmacodynamic studies in geese are recommended to determine the MBX dose regimen and its clinical efficacy in geese.