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.

ABC transporters in the eyes of dogs and implications in drug therapy.

PURPOSE: The current study aims to quantifies the level of expression of selected adenosine triphosphate-binding cassette (ABC) efflux transporters and the major drug metabolizing enzyme CYP450 3A12 in the eyes of dogs. MATERIALS AND METHODS: The levels of expression were quantified by real-time polymerase chain reaction in the cornea, conjunctiva and retinal tissue. RESULTS: ABCB1 mRNA is present at high levels in all analysed tissues. ABCC1, ABCC3 and ABCC4 are expressed predominantly in the conjunctiva and at very low levels in the cornea. ABCC2 could not be detected in any of the tissues. CYP3A12 expression was found in the retina and conjunctiva. CONCLUSION: These data are presented for the first time for ocular tissues of dogs of different breeds and a comparison with other species such as humans and rabbits demonstrated remarkable species differences, which might be of clinical relevance. The impact of these findings is discussed with reference to topical and systemic drug application in the treatment of ophthalmological diseases.