Disposition kinetics of enrofloxacin (Baytril 5%) in sheep and goats following intravenous and intramuscular injection using a microbiological assay

The pharmacokinetics of enrofloxacin were determined in Desert sheep and Nubian goats after intravenous and intramuscular administration of Baytril at the dose of 5mgkg(-1) bodyweight. A two compartment open model best represented the intravenous plasma concentration versus time data in both species. Comparisons between the means of the pharmacokinetic parameters obtained after intravenous administration of enrofloxacin (Baytril) revealed a significantly smaller distribution rate constant (lambda(1)) and consequently a shorter half-life time of distribution in sheep (P<0.05). A larger volume of the central compartment (Vc) was observed in goats (P<0.05). Similar values were obtained for sheep and goats for the remaining parameters.Plasma concentrations versus time data of enrofloxacin after 5mgkg(-1) intramuscular administration of Baytril in sheep and goats were adequately described by one-compartment open model with first order absorption and elimination. There were no significant differences between sheep and goats in any of the estimated pharmacokinetic parameters.The results indicate that the pharmacokinetics of enrofloxacin did not differ significantly between sheep and goats; similar intravenous and intramuscular dose rates of enrofloxacin should therefore be applicable to both species. Owing to the high variations in MIC (minimal inhibitory concentration) of sensitive veterinary pathogens, it is recommended that enrofloxacin dosage regimens be calculated according to the sensitivity of the individual pathogen, site of infection and clinical response, than by following a preset dosage regimen.