Ceftiofur intramuscular injection

Ceftiofiir is absorbed poorly after oral administration but rapidly after intramuscular injection. In all species, ceftiofur was rapidly metabolized to desfuroyl-ceftioftir and fiiroic acid. Desfiiroylceftiofur occurred in the free form in the plasma of treated cattle but was covalently bound to plasma proteins in rats (82). Maximum blood concentrations of ceftiofiir-related residues were achieved within 0.5 and 2 h of dosing. Unmetabolized ceftiofur was generally undetectable in blood within 2-4 h of dosing (83). More than 90% of the administered dose was excreted within 24 h of administration, mostly in urine. Residues in urine and feces were composed primarily of desfiiroylceftiofur and desfiiroylceftiofur cysteine disulfide, with small amounts of unmetabolized ceftiofur. 

After intramuscular injections of radiolabeled ceftiofur to cattle and swine, the compound was absorbed rapidly into the blood and eliminated mostly in urine (84). The tissue in which highest residue concentrations were observed at 12 h after the last dose was the kidney. Most of the radioactivity was found in the form of the microbiologically active primary metabolite, desfiiroylceftiofur, conjugated to macromolecules in plasma and tissues. Desfiiroylceftiofur cysteine was also found in tissues, plasma, and urine, whereas the desfiiroylceftiofur dimer was found in urine. It was suggested that since the binding of desfiiroylceftiofur to biological molecules is reversible, all of the ceftiofiir-related residues that contain the desfuroylceftiofur moiety have the potential to be microbiologically active. 

Milk from lactating cows intramuscularly injected with radiolabeled ceftiofur was found to contain 103 and 50 ppb of total residues at 12 and 24 h, respectively, postdosing. No parent ceftiofur could be detected in milk (85). Therefore, use of ceftiofur at the approved dosage and route is not expected to result in ceftiofiir-related residues exceeding maximum residue limit (MRL) at any time postdosing, and no milk withdrawal periods need to be assigned for ceftiofur. In addition, ceftiofur residues are not hazardous to industrial cheese and yogurt starter cultures. 

Jaglan PS, Yein FS, Homish RE, et al., Depletion of intramuscularly injected ceftiofur from the milk of dairy cattle, J. Dairy Sci. 1992 75 1870-1876. 

Residue depletion studies in pigs after intramuscular administration of ceftiofur showed total residue concentrations of 590, 1190, 250, 400, and 1320 ppb in liver, kidney, muscle, skin/fat, and injection site, respectively, at 12 h after dosing. In cattle, intramuscular administration of radiolabeled ceftiofur resulted in total residue concentrations of 1294, 250, 60, and 60 ppb equivalents in liver 3508, 853, 159, and 159 ppb equivalents in kidney 208, 20, 10, and 10 ppb... 

A unique approach to minimizing tissue residues and thus withdrawal periods is used with Pfizer s ceftiofur product Excenel Sterile Suspension for bovine respiratory disease. This one-time administered Oh-based suspension is injected into the middle section of the ear. During slaughter the ears of cattle are not put into the food chain. The product is also used for swine, but for that species is given intramuscularly. 

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