Mg. Beconibarker et al., METABOLISM OF [C-14] CEFTIOFUR HYDROCHLORIDE IN SWINE AFTER INTRAMUSCULAR INJECTIONS, Journal of agricultural and food chemistry, 45(7), 1997, pp. 2606-2611
Twelve mix-breed swine (26.5-42.5 kg) received three intramuscular dos
es of [C-14]ceftiofur hydrochloride at 24 h intervals. Three males and
three females received 6.76 +/- 0.83 mg of [C-14]ceftiofur free acid
equivalents (CE)/kg body weight (bw)/day, while three males and three
females received 4.41 +/- 0.97 mg of CE/kg bw/day. All swine were euth
anatized 12 h after the last dose. Most of the C-14-residues (> 80%) i
n tissues were associated with macromolecules. The rest of the C-14-ac
tivity corresponded to desfuroylceftiofur (DFC)-cysteine. The type and
percentages of metabolites present in the urine of swine were similar
to those previously observed for ceftiofur sodium (Gilbertson et al.,
J. Agric. Food Chem. 1995, 43, 229-234), with DFC-cysteine and DFC-di
mer being the major ones. In plasma, the major portion of the C-14-act
ivity ( > 85%) was associated with macromolecules. DFC-cysteine was th
e only detectable C-14-component of the macromolecule free plasma frac
tion. This study indicated that ceftiofur hydrochloride was absorbed i
n the same ionic form as ceftiofur sodium, acceding to the same primar
y metabolite DFC. The type of metabolites present in swine after intra
muscular injection were the same, regardless of the salt administered.