Pulmonary disposition of erythromycin, azithromycin, and clarithromycin in foals.

The research investigates and compares the pulmonary disposition, essentially how it is distributed and behaves within the lungs, of three different drugs (azithromycin, clarithromycin, and erythromycin) in foals. Among the three, azithromycin was found to stay in the system the longest, while clarithromycin showed the highest concentration in the pulmonary epithelial lining fluid (PELF). Erythromycin, however, had the lowest activity in both PELF and bronchoalveolar lavage (BAL) cells.

Objective of Research

• The study aimed to understand and compare how azithromycin, clarithromycin, and erythromycin, when given intragastrically, interact with the pulmonary system in foals (young horses).

Methodology

• A single dose of 10 mg/kg of either azithromycin, clarithromycin, or erythromycin was administered intragastrically to six healthy young foals.
• The activity of these drugs was then measured in the serum, pulmonary epithelial lining fluid (PELF), and bronchoalveolar lavage (BAL) cells using a microbiologic assay.

Results

• Clarithromycin resulted in the highest peak drug activity in the PELF among the three drugs.
• Azithromycin, on the other hand, had a longer terminal half-life (the time required for the concentration of the drug to reduce by half) in the serum, PELF, and BAL cells. This indicates that azithromycin stayed in the system the longest.
• Erythromycin was significantly less active in both PELF and BAL cells compared to the other two drugs.

Conclusions

• Of the three antibiotics, clarithromycin had the highest concentration in PELF, implying that it may be most effective in dealing with pulmonary infections in this fluid.
• Azithromycin stayed in the system the longest of the three, meaning it may continue working for a more extended period.
• Erythromycin had the least activity in both PELF and BAL cells, indicating it might be less effective in treating pulmonary conditions in the examined species.