Tissue concentrations and pharmacokinetics of florfenicol in broiler chickens

1. Florfenicol (30 mg/kg body weight) was administered to broiler chickens via intravenous (i.v.), intramuscular (i.m.) and oral routes to study its plasma concentrations, kinetic behaviour, systemic bioavailability and tissue content. 2. Following a single i.v. injection, the kinetic disposition of florfenicol followed a 2-compartmental open model with an elimination half-life of 173 min, total body clearance of 26.9 ml/kg/min and a steady state volume of distribution of 5.11 l/kg. 3. The highest plasma concentrations of florfenicol were 3.82 and 3.20 micrograms/ml following single i.m. and oral administration, respectively. The systemic bioavailability was 96.6% and 55.3% after i.m. and oral administration. The plasma protein binding of florfenicol was 18.5%. 4. Following its administration, the highest tissue concentrations of the drug were found in the kidney bile, lung, muscle, intestine, heart, liver, spleen and plasma. Low concentrations of the drug were found in brain, bone marrow and fat. No florfenicol residues were detected in tissues and plasma after 72 h except in the bile from where it disappeared after 96 h.