Pharmacokinetics of Ceftiofur Crystalline-Free Acid Administered Subcutaneously as a Multiple-Dose Regimen to Neonatal Foals

Subcutaneous (SQ) administration of ceftiofur crystalline-free acid (CCFA, 13.2 mg/kg q 48 hours) in neonatal foals results in plasma concentrations sufficient for the treatment of most bacterial pathogens associated with neonatal septicemia. A dosing interval of 48 hours is recommended to maintain appropriate plasma concentrations in neonatal foals. SQ administration of CCFA appears to be associated with few injection site reactions in neonatal foals. Authors’ addresses: William R. Pritchard Veterinary Medical Teaching Hospital (Hall, Collier, Hill, Monmaney) and Department of Medicine and Epidemiology (Tell, Pusterla, Wetzlich), School of Veterinary Medicine, University of California, Davis, CA 95616. Presenter’s Current Address: Brazos Valley Equine Hospital, Nava- sota, TX 77868; e-mail: [email protected]. *Corresponding author. © 2011 AAEP.

1. Introduction

Ceftiofur crystalline-free acid (CCFA) is a third-generation cephalosporin approved by the Food and Drug Administration for intramuscular administration in horses. The objective of this study was to determine the pharmacokinetics of CCFA administered subcutaneously (SQ) at a dose of 13.2 mg/kg in neonatal foals.

2. Materials and Methods

Group 1 (n = 6) received a single SQ dose (13.2 mg/kg) of CCFA in the axillary region. Group 2 (n = 6) received 4 SQ doses of CCFA (13.2 mg/kg) in the axillary region at 48-hour intervals. Plasma samples were collected at set times after drug administration. Concentrations of ceftiofur-free acid equivalents (CFAE) were determined by high-performance liquid chromatography.

3. Results

Maximum observed plasma concentration was 3.07 ± 0.6 μg/ml and observed time of maximal plasma concentration was 14 ± 4 h after single-dose administration. Area under the concentration (AUC) time curve_{0 to ∞} was 246.2 ± 30.7 h * μg/ml after single administration and AUC_{144 –192} was 172.7 ± 27.1 h * μg/ml for the multidose regimen.

4. Discussion

No significant reactions to injection were observed. CFAE reached sufficient plasma concentrations (>2 μg/ml) when administered every 48 hours to effectively treat common bacterial pathogens.

Acknowledgments

Funding and CCFA^a were provided by Pfizer Animal Health. We would like to thank the staff at the Center for Equine Health, UC Davis, for their support during this study.

Footnote

^a Excede^®, Pfizer Animal Health, 235 E 42^nd Street, New York, NY 10017-5703.