In vitro metabolism of ceftiofur in bovine tissues.

The metabolism of ceftiofur in bovine kidney, liver, muscle and lung, and the effects of the presence of cystine and glutathione in the media were evaluated using S-9 and microsomal tissue fractions. Conversion of ceftiofur to desfuroylceftiofur (DFC) was catalyzed by an esterase which was most active in kidney, followed by liver. It was not very active in muscle and lung.

Ceftiofur hydrochloride: plasma and tissue distribution in swine following intramuscular administration at various doses.

Twelve mixed-breed swine (26.5-42.5 kg) received three daily intramuscular (i.

Determination of ceftiofur and its desfuroylceftiofur-related metabolites in swine tissues by high-performance liquid chromatography.

An HPLC method was developed and validated for the determination of ceftiofur-related metabolites that have the potential to be microbiologically active in swine muscle, kidney, liver and fat. Its performance was evaluated against incurred-residue swine tissues. This method is based on the cleavage of the disulfide and/or thioester bonds between the metabolites and their conjugate sulfur containing moiety using dithioerythritol to yield desfuroylceftiofur, and further stabilization to desfuroylceftiofur acetamide.