Pharmacokinetics of flunixin meglumine in donkeys, mules, and horses.

The research investigates the differences in how the drug flunixin meglumine is absorbed, distributed, metabolized, and excreted in donkeys, mules, and horses. It revealed critical variations in how donkeys process the drug, suggesting that dosage guidelines for horses may not be suitable for donkeys.

Study Design and Methodology

• The study involved a sample of 3 clinically normal horses, 5 clinically normal donkeys, and 5 clinically normal mules.
• Each animal was given a bolus administration of flunixin meglumine, an anti-inflammatory drug, intravenously at a dose of 1.1 mg/kg of body weight.
• Blood samples were collected before administering the drug and after specific time intervals (ranging from 5 minutes to 8 hours post-administration).
• The concentrations of flunixin meglumine in the serum were analyzed in duplicate using high-performance liquid chromatography.
• Noncompartmental pharmacokinetic variables were estimated separately for each horse, donkey, and mule from the serum concentration-time curve.

Research Findings

• The mean area under the curve (AUC), which represents overall drug exposure, for donkeys was significantly less than that of the horses and mules.
• The mean residence time, indicating how long the drug stays in the body, was also significantly shorter for donkeys compared to horses and mules.
• The mean total body clearance rate, representing how quickly the drug is removed from the body, was significantly different in donkeys compared to horses. However, no significant difference was observed between mules and donkeys.
• No significant differences were identified in any pharmacokinetic parameters between horses and mules. This suggests their bodies handle the drug in similar ways.

Conclusions

• There are significant differences in how the drug, flunixin meglumine, is processed by horses, donkeys, and mules.
• These differences are most pronounced between horses and donkeys, indicating that dosing regiments that work for horses may be inappropriate to use in donkeys.