CONICET | Buscador de Institutos y Recursos Humanos

Plasma concentrations of enrofloxacin were determined by high performance liquid chromatography after intravenous (5 mg/kg) and intramuscular (10 mg/kg) administration in southern crested caracaras (Caracara plancus). This compound presented a relatively high volume of distribution (2.09 L/kg), a total body clearance of 0.24 L/kg⋅h and a long permanence as shown by an elimination half-life of 7.81 h and a terminal half-life of 6.58 h, intravenously and intramuscularly, respectively. The areas under the concentration-time curves (AUC) were 21.92 and 34.38 µg.h/ml, for intramuscular and intravenous administrations, respectively. Enrofloxacin was rapidly absorbed after intramuscular administration with a time to reach maximum concentration of 0.72 h and the bioavailability was 78.76%. The peak drug concentration (Cmax) reached after intramuscular administration was 3.92 μg/ml. Values of minimum inhibitory concentration (MIC), Cmax, and AUC have been used to predict the clinical efficacy of a drug in treating bacterial infections, with a Cmax/MIC value of 10 and an AUC/MIC ratio of 125?250 associated with optimal bactericidal effects. By using the study data and a MIC breakpoint of 0.25 µg/ml, values of Cmax/MIC were 13.74 and 15.94 and for AUC/MIC were 90.73 and 139.63, for the intravenous and intramuscular route, respectively. The calculated optimal dose for the treatment of infectious diseases caused by microorganisms with MIC ≤ 0.25 µg/ml were 7.5 and 9,5 mg/kg per day, by the intravenous and intramuscular routes, respectively. For less susceptible bacteria, a dose increase should be evaluated. To treat this species by the intravenous route against microorganisms with MIC ≤ 0.25 µg/ml, the dose should be higher than that administered in our work of 5 mg/kg, but further studies should be conducted in order to assess possible side effects derived from an increase in the IV dose and efficacy in sick birds.