Owing to the low toxicity of ceftiofur in pigs, overdoses do not typically lead to any clinical signs other than transient local swellings as described above.
Ceftiofur is a third generation cephalosporin antibiotic, which is active against many Gram-positive and Gram-negative pathogens. Ceftiofur inhibits bacterial cell wall synthesis, thereby exerting bactericidal properties.
Ceftiofur is particularly active against the following target pathogens causing respiratory and other diseases in pigs: Actinobacillus pleuropneumoniae, Pasteurella multocida, Haemophilus parasuis and Streptococcus suis. Bordetella bronchiseptica is inherently insensitive to ceftiofur in vitro.
Desfuroylceftiofur is the principal active metabolite. It has an antimicrobial activity similar to that of ceftiofur against the target pathogens.
At the recommended therapeutic dose, concentrations in plasma were higher than the MIC90 values (<0.2 µg/ml) for the target bacteria isolated in clinical studies, for at least 158 hours.
After administration, ceftiofur is quickly metabolised to desfuroylceftiofur, the principal active metabolite.
Protein binding of ceftiofur and its major metabolite is approximately 70%. One hour after a single administration, plasma concentrations are above 1 µg/ml. Maximum concentrations in plasma (4.2 ± 0.9 µg/ml) are reached at approximately 22 hours after administration. Plasma concentrations above 0.2 µg/ml of ceftiofur and its metabolite are maintained for an appropriate period of time.
Approximately 60 % and 15 % of the dose are excreted in the urine and faeces respectively, within 10 days after administration.