Pharmacokinetics and bioavailability of moxifloxacin in buffalo calves

The pharmacokinetics of moxifloxacin were investigated in buffalo calves following a single intravenous and intramuscular administration of moxifloxacin (5 mg kg(-1) body wt.). Moxifloxacin concentrations in plasma and urine were determined by microbiological assay. Pharmacokinetic analysis of disposition data indicated that intravenous administration data were best described by a two compartment open model, whereas intramuscular administration data were best described by a one compartment open model. Following intravenous administration, the elimination half life (t(1/2beta)), volume of distribution (Vd(area)) and total body clearance were 2.69+/-0.14 h, 1.43+/-0.08 L kg(-1) and 371.2+/-11.2 ml kg(-1)h(-1), respectively. Following intramuscular administration, the absorption half life (t(1/2ka)) was 0.83+/-0.20 h. The systemic bioavailability (F) of moxifloxacin in buffalo calves was 80.0+/-4.08%. Urinary excretion of moxifloxacin was less than 14% after 24h of administration of drug. In vitro binding of moxifloxacin to plasma proteins of buffalo calves was 28.4+/-3.77%. From the data of surrogate markers (AUC/MIC, C(max)/MIC), it was determined in the buffalo calves that when administered by intravenous or intramuscular route at 5 mg kg(-1), moxifloxacin is likely to be effective against bacterial isolates with MIC< or =0.1 microg ml(-1).