Pharmacokinetics of ceftriaxone in buffalo calves (Bubalus bubalis) following intravenous and intramuscular administration

Summary Pharmacokinetics of ceftriaxone was studied in buffalo calves (Bubalus bubalis) after single intravenous and intramuscular administration of 10 mg/kg body weight. The drug concentrations in plasma samples were measured by high performance liquid chromatography with UV detection. Following intravenous administration, the drug was rapidly distributed (Cp o : 106.5 ± 9.64 µg/ml; t1/2α: 0.09 ± 0.01 h; Vdarea: 0.48 ± 0.05 L/kg) and eliminated (t1/2β: 1.27 ± 0.04 h) from the body with a clearance rate of 4.40 ± 0.44 ml/min.kg. Following intramuscular administration, the peak plasma concentration of the drug was 15.8 ± 2.4 µg/ml at 0.5 h and the drug was detected up to 12 h. The drug was rapidly absorbed from the site of injection (t1/2ka: 0.35 ± 0.01 h), widely distributed (Vdarea: 1.53 ± 0.2 L/kg) and slowly eliminated from the body (t1/2β: 4.38 ± 0.4 h; ClB: 4.01 ± 0.30 ml/min.kg). The bioavailability of ceftriaxone was 70.2 ± 2.0% following intramuscular injection. Intramuscular injection of ceftriaxone has favourable pharmacokinetics and moderate bioavailability in buffalo calves and can be used for susceptible infections in calves.