Pharmacokinetics of Ceftiofur Sodium in Equine Pregnancy

Ceftiofur sodium had poor penetration into fetal membranes and compartments after administration to normal, pregnant mares. This drug is not recommended for treating mares with placentitis. Authors’ addresses: Large Animal Clinical Sciences (Macpherson, Pozor, Benson, Runcan, Hatzel, Larson, van den Berg, Kelleman, Sanchez), and Physiological Sciences (Vickroy), College of Veterinary Medicine, University of Florida, Gainesville, FL 32610; Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 (Gigue`re); The Gluck Center, University of Kentucky, Lexington, KY 40546 (Troedsson); and Rood and Riddle Equine Hospital, PO Box 12070, Lexington, KY 40580-2070 (LeBlanc); e-mail: macphersonm@ufl.edu.

1. Introduction

The pharmacokinetics and drug disposition of ceftiofur sodium, after administration to pregnant mares, was evaluated.

2. Methods

Eleven pregnant pony mares (D270–326) were administered ceftiofur sodium intramuscularly at 2.2 mg/kg (low dose; n = 6) or 4.4 mg/kg (high dose; n = 5). Plasma was obtained at T = 0, 0.5, 1, 2, 4, 8, 12, and 24 h after ceftiofur administration. Eight pony mares were re-enrolled in the study ≥ 3 days from foaling to ensure steady state concentrations of the drug at the time of foaling. Mares were administered ceftiofur sodium (4.4 mg/kg, IM) daily until foaling. Parturition was induced one hour after ceftiofur sodium administration. Allantoic and amniotic fluid, plasma (mare and foal) colostrum, and placental samples were collected at delivery and for 24 h. Samples were analyzed for desfuroylceftiofur acetamide (DCA) concentrations by high performance liquid chromatography (HPLC). 

3. Results and Discussion

Mean (± SD) peak concentrations of DCA were 3.97 ±􏰊 0.50 mcg/mL (low dose) and 7.45 ± 1.05 mcg/mL (high dose). Terminal half-life was shorter after administration of the low dose (2.91 ± 0.59 h) than after the high dose (4.10 ± 0.72 h). The mean plasma concentration of DCA from mares at foaling was 7.96 ± 1.39 mcg/mL and colostrum was 1.39 ± 0.70 mcg/mL. The DCA concentrations in allantoic and amniotic fluid, placental tissues, and foal plasma were nearly undetectable. These results infer incomplete passage of DCA across fetal membranes after administration of ceftiofur sodium to normal pony mares.

Acknowledgments

Conflict of Interest

This work was supported by the Grayson-Jockey Club Research Foundation and Zoetis Animal Health.