الكاتب: Multiple References

A study was conducted to measure concentrations of potentially active ceftiofur derivatives, in plasma, in uterine tissues (endometrium and caruncles) and in uterine secretions at different time points after a single subcutaneous administration of ceftiofur hydrochloride (ExcenelÒ RTU Sterile Suspension) at the dose of 1 mg/kg body weight in Holstein±Friesian dairy cows. The animals (n ˆ 4) were injected within 24 h of calving, after expulsion of the foetal membranes. Plasma, lochial ¯uid, caruncles and endometrium were collected before ceftiofur hydrochloride administration and at 1, 2, 4, 8, 12 and 24 h after treatment. For each cow the concentrations of ceftiofur in the biological matrices were quanti®ed using an high-performance liquid chromatography (HPLC) assay. The limit of quanti®cation of the method was 0.1 lg/mL for plasma and 0.1 lg/g for lochial ¯uid, caruncles and endometrium. The concentrations of potentially active ceftiofur derivatives detected in plasma reached a maximum of 2.85 ‹ 1.11 lg/mL at 2 h and decreased to 0.64 ‹ 0.14 lg/ mL at 24 h after administration. In lochial ¯uid, these concentrations reached a maximum of 0.97 ‹ 0.25 lg/g at 4 h and decreased to 0.22 ‹ 0.21 lg/g at 24 h after administration. In endometrium, these concentrations reached a maximum of 2.23 ‹ 0.82 lg/g at 4 h and decreased to 0.56 ‹ 0.14 lg/g at 24 h following the injection, whereas these levels in caruncles were 0.96 ‹ 0.45 and 0.60 ‹ 0.39 lg/g obtained at 8 and 24 h, respectively. At the dose of 1 mg/kg body weight in healthy dairy cows, subcutaneous administration of ceftiofur (as ceftiofur hydrochloride) after parturition results in concentrations of ceftiofur derivatives in uterine tissues and in lochial ¯uid that exceed the reported minimal inhibitory concentrations (MICs) for the common pathogens (Escherichia coli, Fusobacterium necrophorum, Bacteroides spp., and Arcanobacterium pyogenes) associated with acute puerperal metritis.