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.m.) doses of 14C-ceftiofur hydrochloride. Three males and three females, received 6.76 +/- 0.83 mg of 14C-ceftiofur free acid equivalents (CFAE)/kg body weight (b.w.)/day, while the other group received 4.41 +/- 0.97 mg.CFAE/kg b.w./day. The swine were slaughtered 12 h following the last dose. Total dose accountability for the 6.76 mg dose was 91.44 +/- 16.11% (72.51% in urine; 12.63% in faeces). For the 4.41 mg dose, accountability was 100.35 +/- 20.45% (82.48% in urine; 12.85% in faeces). Within the tissues used for residue monitoring, the highest concentrations were observed in the kidneys (10.68 and 6.33 micrograms.CFAE/g for the 6.76 and 4.41 mg doses, respectively), followed by the injection sites, lungs, liver and muscle. In a separate study, twelve mix-breed swine (23.1-39.7 kg) received 14C-ceftiofur hydrochloride at 3.08 mg.CFAE/kg b.w. once daily for 3 days. Two males and two females were slaughtered at either 12, 72 or 120 h after the last dose. Total dose accountability for the 3.08 mg dose was > 83% (> 68% in urine; > 13% in faeces). In swine slaughtered 12 h after last dose, residue concentrations closest to the safe concentrations were observed in the kidneys (3.62 micrograms.CFAE/g), followed by the injection sites, lungs, liver and muscle.