Pharmacokinetics and bioavailability of cefquinome and ceftriaxone in premature calves

The aim of this study was to evaluate the pharmacokinetics and bioavailability of cefquinome (CFQ) and ceftriaxone (CTX) following intravenous (IV) and intramuscular (IM) administrations in premature calves. Using a parallel design, 24 premature calves were randomly divided into the two antibiotic groups. Each of the six animals in the first group received CFQ (2 mg/kg) through IV or IM administration. The second group received CTX (20 mg/kg) via the same administration route. Plasma concentrations of the drugs were analyzed by high-performance liquid chromatography and noncompartmental methods. Mean pharmacokinetic parameters of CFQ and CTX following IV administration were as follows: elimination half-life (t_1/2λz ) 1.85 and 3.31 hr, area under the plasma concentration-time curve (AUC_0-∞ ) 15.74 and 174 hr * μg/ml, volume of distribution at steady-state 0.37 and 0.45 L/kg, and total body clearance 0.13 and 0.12 L hr^-1  kg^-1 , respectively. Mean pharmacokinetic parameters of CFQ and CTX after IM injection were as follows: peak concentration 4.56 and 25.04 μg/ml, time to reach peak concentration 1 and 1.5 hr, t_1/2λz 4.74 and 3.62 hr, and AUC_0-∞ 22.75 and 147 hr * μg/ml, respectively. The bioavailability of CFQ and CTX after IM injection was 141% and 79%, respectively. IM administration of CFQ (2 mg/kg) and CTX (20 mg/kg) can be recommended at 12-hr interval for treating infections caused by susceptible bacteria, with minimum inhibitory concentration values of ≤0.5 and ≤4 μg/ml, respectively, in premature calves. However, further research is indicated to assess the pharmacokinetic parameters following multiple doses of the drug in premature calves.