Comparative pharmacokinetics of enrofloxacin, danofloxacin, and marbofloxacin after intravenous and oral administration in Japanese quail (Coturnix coturnix japonica).

A population approach was used to evaluate the pharmacokinetic parameters of 3 fluoroquinolones administered to Japanese quail (Coturnix coturnix japonica). Healthy adult quail (n = 50) were divided into 3 groups, each administered a separate intravenous and oral dose of the compounded drug: enrofloxacin at 10 mg/kg (n = 18; 9 male, 9 female), danofloxacin at 10 mg/kg (n = 12; 6 male, 6 female), and marbofloxacin at 5 mg/kg (n = 20; 10 male, 10 female). A fourth group was used as a control (n = 5). Enrofloxacin was metabolized extensively to ciprofloxacin, while no metabolites of either danofloxacin or marbofloxacin were detected. The volume of distribution was high, greater than 1 in all cases, and highest for danofloxacin, followed by enrofloxacin, then marbofloxacin. The total body clearance was higher in quail than that reported for other avian species with the exception of ostriches. As in mammals, the lowest clearance rate of the 3 fluoroquinolones was observed for marbofloxacin. Enrofloxacin was absorbed most rapidly, followed by marbofloxacin, then danofloxacin. The highest bioavailability was observed for danofloxacin followed by marbofloxacin, while very low bioavailability with significant conversion to ciprofloxacin was observed for enrofloxacin. Population analysis showed low intersubject variability for danofloxacin and marbofloxacin in contrast to that for enrofloxacin and its main metabolite, ciprofloxacin. Because of their more favorable pharmacokinetic properties after oral administration, either danofloxacin or marbofloxacin appears to be preferable to enrofloxacin for the treatment of susceptible bacterial infection in Japanese quail.

Pharmacokinetics of tobramycin in ducks and sex-related differences.

The aims of the present study were to determine the disposition of tobramycin after single intravenous (IV) and intramuscular (IM) injections in ducks, and to establish any sex-related differences. Tobramycin sulfate was administered as a 2.5% water solution in a cross-over design at a dose of 5mg/kg to 12 healthy ducks (six males and six females). Concentrations of the drug in serum were determined by a microbiological assay. The serum pharmacokinetic values for tobramycin were best represented using a one- or two-compartment open model, depending on the method of administration. Non-compartment analysis was also performed after IV administration. Tobramycin had a low degree of distribution and a relatively fast elimination. The mean volume of distribution in ducks (males and females) was higher than that reported in pigeons but lower than in chickens, with a slower rate of elimination. The IM injection resulted in a fast and complete absorption. The rate of elimination after IM administration was about twice as slow as in other avian species. Sex-related variations in tobramycin pharmacokinetics were similar to those reported for kanamycin and apramycin in hens and roosters.