Some pharmacokinetic aspects and bioavailability of marbofloxacin in foals

The single-dose pharmacokinetics of marbofloxacin was studied in clinically normal foals after intravenous and intramuscular administration of 5 mg of marbofloxacin/kg of body weight. Marbofloxacin concentrations were determined by microbiological assay method. The disposition of marbofloxacin was best described by a two-compartment open model after a single intravenous injection while, by a one-compartment open model after intramuscular administration. The distribution half-life, elimination half-life, mean residence time of marbofloxacin after intravenous injection were 0.27, 6.4, 6.8 h after 5 mg/kg dose. Following intramuscular administration, the drug absorbed at a fast rate as indicated by short absorption half-life (t0.5(ab)) of 0.26 h. The drug was eliminated at a slow rate with an elimination half-life t0.5(el) of 7.16 h after 5 mg/kg dose. The extent of serum protein binding was 27.5%. These results indicate that a dose of 5 mg of marbofloxacin/kg administered as a single dose once daily could be useful in the treatment of diseases caused by sensitive pathogens in foals after specific assessments.