Pharmacokinetics of long-acting ceftiofur crystalline-free acid in helmeted guineafowl (Numida meleagris) after a single intramuscular injection.

OBJECTIVE

To evaluate the elimination pharmacokinetics of a single i.m. injection of a long-acting ceftiofur preparation (ceftiofur crystalline-free acid [CCFA]) in healthy adult helmeted guineafowl (Numida meleagris).

ANIMALS

14 healthy adult guineafowl.

PROCEDURES

1 dose of CCFA (10 mg/kg) was administered i.m. to each of the guineafowl. Blood samples were collected intermittently via jugular venipuncture over a 144-hour period. Concentrations of ceftiofur and all desfuroylceftiofur metabolites were measured in plasma via high-performance liquid chromatography.

RESULTS

No adverse effects of drug administration or blood collection were observed in any bird. The minimal inhibitory concentration (MIC) for many bacterial pathogens of poultry and domestic ducks (1 μg/mL) was achieved by 1 hour after administration in most birds and by 2 hours in all birds. A maximum plasma concentration of 5.26 μg/mL was reached 19.3 hours after administration. Plasma concentrations remained higher than the MIC for at least 56 hours in all birds and for at least 72 hours in all but 2 birds. The harmonic mean ± pseudo-SD terminal half-life of ceftiofur was 29.0 ± 4.93 hours. The mean area under the curve was 306 ± 69.3 μg•h/mL, with a mean residence time of 52.0 ± 8.43 hours.

CONCLUSIONS AND CLINICAL RELEVANCE

A dosage of 10 mg of CCFA/kg, i.m., every 72 hours in helmeted guineafowl should provide a sufficient plasma drug concentration to inhibit growth of bacteria with an MIC ≤ 1 μg/mL. Clinical use should ideally be based on bacterial culture and antimicrobial susceptibility data and awareness that use of CCFA in avian patients constitutes extralabel use of this product.