Wa. Moats et Sa. Buckley, DETERMINATION OF FREE METABOLITES OF CEFTIOFUR IN ANIMAL-TISSUES WITHAN AUTOMATED LIQUID-CHROMATOGRAPHIC CLEANUP, Journal of AOAC International, 81(4), 1998, pp. 709-713
Ceftiofur, a recently introduced antibiotic of the beta-lactam group,
is rapidly converted to both free and protein-bound metabolites when a
dministered by the prescribed procedure, intramuscular injection. Free
metabolites retain antimicrobial activity and may be detected by anti
biotic-screening tests based on antimicrobial activity. It is thus des
irable to distinguish ceftiofur metabolites from other antibiotics. A
multiresidue procedure for p-lactams in milk was adapted for determina
tion of free ceftiofur metabolites by collecting appropriate liquid ch
romatographic fractions during cleanup. analysis of tissues from treat
ed animals showed that the principal free metabolite was the desfuroyl
ceftiofurcysteine conjugate.