DAO 121:29-35 (2016)  -  DOI: https://doi.org/10.3354/dao03032

ABSTRACT: Ceftiofur is a broad-spectrum third generation cephalosporin, which acts by inhibiting bacterial cell wall synthesis. It is active against Gram-positive and Gram-negative bacteria such as Aeromonas hydrophila and β-lactamase-producing strains, which are common pathogens in freshwater fish. Ceftiofur pharmacokinetics in Nile tilapia  Oreochromis niloticus were studied following single intracardiac (i.c.) or intramuscular (i.m.) administration of ceftiofur sodium (NAXCEL^®) in a dose of 5 mg ceftiofur kg^-1 body weight. After i.c. injection, ceftiofur plasma concentrations decreased biexponentially, suggesting a 2-compartmental open model. Distribution and elimination half-lives (t_0.5(α) and t_0.5(β)) were 0.61 ± 0.22 and 0.14 ± 0.03 h mean ±SD, respectively. Elimination constant (K_el) and total body clearances (Cl_tot) were 3.22 ± 0.48 h^-1 and 1.64 ± 0.47 l h^-1 kg^-1, respectively. Volume of distribution (Vss) and areas under curves (AUC) were 0.12 ± 0.03 l kg^-1 and 24.18 ± 8.81 µg ml^-1 h, respectively. Following i.m. injection of ceftiofur, plasma concentrations were best described by a 1-compartment open model with a first order absorption; bioavailability was quite high (96.85 ± 23.74%). Plasma maximum concentration (C_max) was 12.32 ± 6.53 µg ml^-1; achieved at time of maximum concentration (T_max) of 0.74 ± 0.04 h. Absorption and elimination half-lives (t_0.5(ab) and t_0.5(β)) were 0.49 ± 0.06 and 0.53 ± 0.03 h, respectively. In conclusion, i.m. injection of ceftiofur sodium produced extremely high bioavailability with high plasma concentrations that persisted up to 6 h post injection, which may make ceftiofur a useful alternative antibiotic for treatment of brood stock or important ornamental fishes.

KEY WORDS: Ceftiofur · Cephalosporin · Pharmacokinetics · Teleosts · Tilapia · Intracardiac · Intramuscular