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Comparison of continuous infusion with intermittent bolus administration of cefotaxime on blood and cavity fluid drug concentrations in neonatal foals

Authors


  • Present address: Dr Diaz’s, Department of Pathobiology, University of Guelph, and Dr Ruiz’s, Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan.

  • This study was funded by the Equine Guelph Research Fund and was supported by operational funds from the Ontario Ministry of Agriculture, Food and Rural Affairs.

Dr Joanne Hewson, Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada N1G 2W1. E-mail: jhewson@uoguelph.ca

Abstract

Hewson, J., Johnson, R., Arroyo, L. G., Diaz-Mendez, A., Ruiz-López, J. A., Gu, Y., del Castillo, J. R. E. Comparison of continuous infusion with intermittent bolus administration of cefotaxime on blood and cavity fluid drug concentrations in neonatal foals. J. vet. Pharmacol. Therap. 36, 68–77.

Healthy neonatal foals were treated with cefotaxime by bolus (40 mg/kg IV q6h for 12 doses; n = 10) or by infusion (loading dose of 40 mg/kg IV followed by continuous infusion of a total daily dose of 160 mg/kg per 24 h for 3 days; n = 5). Population pharmacokinetics was determined, and concentrations in cavity fluids were measured at steady state (72 h). Highest measured serum drug concentration in the bolus group was 88.09 μg/mL and minimum drug concentration (Cmin) was 0.78 μg/mL at 6-h postadministration (immediately before each next dose), whereas infusion resulted in a steady-state concentration of 16.10 μg/mL in the infusion group. Mean cefotaxime concentration in joint fluid at 72 h was higher (= 0.051) in the infusion group (5.02 μg/mL) compared to the bolus group (0.78 μg/mL). Drug concentration in CSF at 72 h was not different between groups (= 0.243) and was substantially lower than serum concentrations in either group. Insufficient data on pulmonary epithelial lining fluid were available to compare the methods of administration for cefotaxime in this cavity fluid. Results support continuous drug infusion over bolus dosing in the treatment for neonatal foal septicemia to optimize time that cefotaxime concentration exceeds the minimum inhibitory concentration of common equine pathogens.

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