Bioavailability and pharmacokinetic profile of levofloxacin following intravenous, intramuscular and oral administration in turkeys

1. The pharmacokinetics and bioavailability of levofloxacin in turkeys were investigated after a single intravenous (IV), intramuscular (IM) and oral (PO) administration of 10mg/kg body weight.2. The concentrations of levofloxacin in plasma samples were assayed using a microbiological assay method and pharmacokinetic parameters were calculated by non-compartmental analysis.3. Following IV administration, the elimination half-life (t(0.5())), volume of distribution at steady state (Vd(ss)) and total body clearance (Cl) were 4.49h, 1.31l/kg and 0.23l/h/kg, respectively.4. After single IM and PO administrations at the same dose, levofloxacin was rapidly absorbed as indicated by an absorption half-life (t(0.5ab)) of 1.02 and 0.76h, respectively; maximum plasma concentrations (C-max) of 5.59 and 5.15g/ml were obtained at a maximum time (T-max) of 2 h for both routes and levofloxacin bioavailability (F) was 96.5h and 79.9% respectively after IM and PO administration. In vitro plasma protein binding of levofloxacin was 24.3%.5. Based on these pharmacokinetic parameters, a dose of 10mg/kg body weight given intramuscularly or orally every 24h in turkeys can maintain effective plasma concentrations with bacterial infections with (minimum inhibitory concentration) MIC90>0.1g/ml.