Plasma and pulmonary disposition of ceftiofur and its metabolites after intramuscular administration of ceftiofur crystalline free acid in weanling foals.

This research paper investigates the distribution and effects of the antibiotic Ceftiofur Crystalline Free Acid (CCFA) within the blood and lungs of weanling foals, comparing the results with adult horses. The antibiotic was administered intramuscularly, and data from the research suggests it could potentially serve as an effective treatment for certain pneumonia in foals.

Examining the Plasma and Pulmonary Disposition of CCFA in Foals:

• The first objective of this study was to establish the plasma and pulmonary disposition of CCFA in weanling foals. Researchers administered a single dose of CCFA, intramuscularly, to six weanling foals under controlled conditions.
• The researchers traced the spread and concentration of a CCFA metabolite called desfuroylceftiofur acetamide (DCA) within the plasma of these foals and within their pulmonary epithelial lining fluid (PELF) and bronchoalveolar lavage (BAL) cells.
• This investigation indicated that the median time for CCFA to achieve the maximum plasma and PELF concentrations in weanling foals was 24 hours.

Comparing CCFA Concentrations in the Plasma, PELF, and BAL Cells:

• The study also aimed to compare the plasma pharmacokinetic profile of weanling foals and adult horses after the administration of CCFA.
• The peak DCA concentration in plasma was significantly (statistically) higher compared to its concentration in PELF and BAL cells.
• The duration for which the plasma maintained a DCA concentration above the therapeutic target measure was longer than in PELF. However, DCA concentration in BAL cells did not reach the therapeutic level at all.

Comparing the Effects of CCFA on Adult Horses and Foals:

• Lastly, the researchers discovered that adult horses had notably lower peak plasma concentrations and a smaller area under the curve when compared to foals.
• These findings indicate that foals and adult horses have different responses to the administered CCFA doses, suggesting a potential need for age-adjusted dosage prescriptions.

Potential Implications and Conclusions:

• The results suggest that applying CCFA to weanling foals intramuscularly at a dose of 6.6 mg/k of body weight can provide plasma and PELF concentrations above the therapeutic target (0.2 μg/mL) for at least 4 days.
• This observation hints that CCFA could potentially be an effective treatment for pneumonia induced by Streptococcus equi subsp. zooepidemicus in weanling foals, with doses similar to that required for adults.