Pharmacokinetic behaviour of enrofloxacin following single dose administration, by different routes, in rheas.

DE LUCAS, JJ; RODRIGUEZ,C; NAVARRO, JL.; MARTELLA, MB; LABAQUE, MC.; VIGNOLO, P.; ASIS, V; SAN ANDRES, MJ

Madrid, España

Congreso; 3rd International Ratite Science Symposium; 2005

World´s Poultry Science Association

The kinetic behaviour of enrofloxacin (ENR) and its active metabolite ciprofloxacin (CIP) was studied in eighteen healthy domestic rheas ages 3-5 months and eighing 2.4-3.5 kg. The rheas were randomly allocated into three treatment groups. Group I: Baytrilâ 5% i.s. was administered i.v and then i.m. at a dose of 15mg/kbw, following an 8 day washout period. Group II: Baytrilâ 5% i.s. was administered s.c. at a dose of 15mg/kbw.  Group III: Baytrilâ 5% o.s. was administered  per os at a dose of 30mg/kbw. ENR and CIP plasmatic levels were simultaneously quantified using an HPLC/u.v technique. ENR was rapidly absorbed (Tmaxim=0.4 h; Tmaxsc= 0.6 h and Tmaxvo=3.2 h) and reached high plasma levels (Cmaxim=3,30 mgr/ml; Cmaxsc=2.12 mgr/ml; Cmaxvo= 0.82 mgr/ml). The bioavailability of this drug was aproximately 100% by i.m. and s.c. routes and 54±13% by oral administration. The high volume of distribution (5.01 L/Kg) is suggestive of good tissue penetration, which is higher than that described in other avian and mamalian species. Moreover, clearance is very rapid which explains the detected low plasmatic levels and its short maintenance after i.v., i.m. and s.c. administration (MRTiv=1.23h; MRTim=1.40h¸ MRTsc=1.82h). Interspecies differences are important in enrofloxacin elimination and implicate the risk of extrapolating doses and treatments from any species to rheas, without suitable pharmacokinetic data. These data suggest that due to the excellent tissue penetration; enrofloxacin may serve as a good chemotherapeutic alternative for treatment of infections with highly susceptible bacteria e.g. E. coli in rheas. *This study was supported by a grant from the UCM (PR3/04-12470).