Single intravenous and oral pharmacokinetics of danofloxacin in the goat

Respiratory diseases including pneumonia are a common concern in goats, with M. Haemolytica the usual causative organism. Owing to danofloxacin's wide spectrum of activity, it is used to treat such disease in goats. The aim of the present study was to investigate danofloxacin pharmacokinetics in the goat after single intravenous (IV) and oral (PO) administration. Sixteen healthy goats were randomly divided into two groups. The first group (n = 8) was administered danofloxacin IV (6 mg/kg) and the second group (n = 8) was administered danofloxacin PO (12 mg/kg). Blood was collected from 0 to 36 h after drug administration. Plasma samples were analyzed for danofloxacin content using a validated HPLC-FL method. The pharmacokinetic analysis was performed using a non-compartmental model, and the PK/PD index was used to predict the antimicrobial effect of danofloxacin. Danofloxacin was quantifiable up to 36 h for both administration routes. After IV administration, danofloxacin demonstrated a long t1/2kel (10.09 h), with a Cl of 0.69 mL/g*h and a Vss of 2.66 mL/g. Unfortunately, an unanticipated long-lasting absorption phase after PO administration only allowed calculation of Cmax (0.13 μg/mL), Tmax (8 h) and AUC(0-t) (2.74 h). The PK/PD surrogate for the prediction of a fluoroquinolone's efficacy (AUC(0–24)/MIC), corrected for danofloxacin's low plasma protein binding, suggested that a single PO danofloxacin dose at 12 mg/kg may be effective against M. haemolytica in the goat.