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.