LUNG-TISSUE CONCENTRATIONS AND PLASMA PHARMACOKINETICS OF DANOFLOXACIN IN CALVES WITH ACUTE PNEUMONIA

Plasma and lung tissue pharmacokinetics of danofloxacin in calves with naturally induced acute pneumonia were determined in 2 separate studi es. A maximal pneumonic tissue concentration of 1.17 mug/g was achieve d 1.8 hours after im injection of 1.25 mg of danofloxacin/kg of body w eight. Pneumonic tissue danofloxacin concentrations were 5.5 times gre ater than those in plasma at 1 and 2 hours after injection. Craniovent ral pneumonic tissue had significantly decreased danofloxacin concentr ation, compared with that of grossly normal tissue from the caudodorsa l part of the lungs at 2 of 6 sample times. After IV injection, the ap parent steady-state volume of distribution was 3.44 +/- 1.13 mug, and the elimination half-life was 6.26 +/- 2.27 hours. Maximal plasma dano floxacin concentration of 0. 2 5 mug/ml was detected 0.80 hour after i m injection. Bioavailability was 91%. Our findings indicated that a la rge percentage of danofloxacin is rapidly absorbed after im administra tion to calves with acute pneumonia, Extensive tissue penetration was suggested by a high steady-state volume of distribution and was indica ted by high concentrations in pneumonic tissue.