Pharmacokinetics of ceftiofur crystalline free acid after single and multiple subcutaneous administrations in healthy alpacas (Vicugna pacos)

Six adult male alpacas received one subcutaneous administration of ceftiofur crystalline free acid (CCFA) at a dosage of 6.6mg/kg. After a washout period, the same alpacas received three subcutaneous doses of 6.6mg/kg CCFA at 5-day intervals. Blood samples collected from the jugular vein before and at multiple time points after each CCFA administration were assayed for ceftiofur- and desfuroylceftiofur-related metabolite concentrations using high-performance liquid chromatography. Pharmacokinetic disposition of CCFA was analyzed by a noncompartmental approach. Mean pharmacokinetic parameters (±SD) following single-dose administration of CCFA were C_max (2.7±0.9μg/mL); T_max (36±0h); area under the curve AUC_0→∞ (199.2±42.1μg·h/mL); terminal phase rate constant λz (0.02±0.003/h); and terminal phase rate constant half-life t_1/2λz (44.7h; harmonic). Mean terminal pharmacokinetic parameters (±SD) following three administrations of CCFA were C_max (2.0±0.4μg/mL); T_max (17.3±16.3h); AUC_0→∞ (216.8±84.5μg·h/mL); λz (0.01±0.003/h); and t_1/2λz (65.9h; harmonic). The terminal phase rate constant and the T_max were significantly different between single and multiple administrations. Local reactions were noted in two alpacas following multiple CCFA administrations.