Comparative pharmacokinetics of orbifloxacin in healthy and Pasteurella multocida infected ducks.

The pharmacokinetic aspects of orbifloxacin were studied in both healthy and naturally diseased ducks after a single intravenous and intramuscular dose of 5 mg kg⁻¹ body weight. The serum concentrations of orbifloxacin following single intravenous and intramuscular injections were higher in diseased than in healthy ducks. The disposition of orbifloxacin after a single intravenous injection was described by a two-compartment open model in both healthy and diseased ducks. Orbifloxacin was distributed and eliminated at a significantly slower rate in diseased than in healthy ducks. The total body clearance (Cl(B)) was lower in diseased (0·131 l kg⁻¹h⁻¹) than healthy ducks (0·191 l kg⁻¹h⁻¹). Following intramuscular administration of orbifloxacin, the peak serum concentration (C(max)) was higher in diseased than in healthy ducks, and this was achieved at a maximum time (t(max)) of 1·114 and 0·993 h, respectively. The drug was eliminated at a significant slower rate in diseased ducks (elimination half-life t (0·5(el))= 5·07 h) than in healthy ducks (elimination half-life t (0·5(el))= 4·18 h). These results indicate that drug elimination patterns in healthy and diseased ducks are not the same. The pharmacokinetic profile of the drug is altered in diseased ducks due to the increased serum orbifloxacin concentrations compared with clinically healthy ducks. In conclusion, 5 mg kg⁻¹ body weight of orbifloxacin administered as a single dose once daily could be useful in the treatment of disease caused by Pasteurella multocida pathogen in ducks.