Absorption of enroﬂoxacin and marboﬂoxacin after oral and subcutaneous administration in diseased koalas (Phascolarctos cinereus)
J. E. GRIFFITH* D. P. HIGGINS* K. M. LIt M. B. KROCKENBERGER* & M. GOVENDIR*
*Faculty of Veterinary Science; tSydney Medical School, The University of Sydney, Camperdown, NSW, Australia
Koalas (n = 43) were treated daily for up to 8 weeks with enroﬂoxacin: 10 mg⁄kg subcutaneously (s.c.), 5 mg⁄kg s.c., or 20 mg⁄kg per os (p.o.); or marboﬂoxacin: 1.0–3.3 mg⁄kg p.o., 10 mg⁄kg p.o. or 5 mg⁄kg s.c. Serial plasma drug concentrations were determined on day 1 and again at approximately 2 weeks, by liquid chromatography. The median (range) plasma maximum concentrations (Cmax) for enroﬂoxacin 5 mg⁄kg s.c. and 10 mg⁄kg s.c. were 0.83 (0.68–1.52) and 2.08 (1.34–2.96) µg⁄mL and the median (range) Tmax were 1.5 h (1–2) and 1 h (1–2) respectively. Plasma concentrations of orally dosed marboﬂoxacin were too low to be quantiﬁed. Oral administration of enroﬂoxacin suggested absorption rate limited disposition pharmacokinetics; the median (range) Cmax for enroﬂoxacin 20 mg⁄kg p.o. was 0.94 (0.76–1.0) µg⁄mL and the median (range) Tmax was 4 h (2–8). Oral absorption of both drugs was poor. Plasma protein binding for enroﬂoxacin was 55.4 ± 1.9% and marboﬂoxacin 49.5 ± 5.3%. Elevations in creatinine kinase activity were associated with drug injections. Enroﬂoxacin and marboﬂoxacin administered at these dosage and routes are unlikely to inhibit the growth of chlamydial pathogens in vivo.