Effect of body weight on the pharmacokinetics of flunixin meglumine in miniature horses and quarter horses.

This research concerns the effect of bodyweight on how the medication flunixin meglumine is processed in miniature horses compared to light-breed horses. The study found no noticeable differences between the two and thus suggests using the same dosage for both types of horses.

Study Purpose and Methodology

• The study aimed to find out if miniature horses should be given different dosage of flunixin meglumine (a non-steroidal anti-inflammatory drug, NSAID, used in horses) compared to light-breed horses, such as quarter horses.
• This is due to the large size disparity between these types of horses and the common practice of adjusting medication dosages based on bodyweight among different species.
• The researchers conducted the experiment by injecting the standard dose of flunixin meglumine intravenously to eight horses from each breed. They used a three-compartmental analysis method to compare the pharmacokinetic parameters between the two groups.

Key Findings

• The total body clearance of flunixin meglumine drug was found to be almost the same among miniature horses and quarter horses (0.97 ± 0.30 mL/min/kg and 1.04 ± 0.27 mL/min/kg, respectively).
• The study did not find significant differences between the breeds in terms of total body clearance, terminal elimination rate (the rate at which the drug is expelled from the body), and the area under the plasma concentration versus time curve (a measure of the overall exposure of the body to the drug).
• In addition, apparent volume of distribution at steady-state (the volume into which a drug would need to be evenly distributed to produce the observed blood concentration) and volume of the central compartment (volume in the body where the drug appears to stay) for flunixin were also similar between miniature and quarter horses.

Conclusion

• The findings suggested that despite the size variation between miniature horses and light-breed horses, the same dosage of flunixin meglumine can be used for both breeds.
• The researchers recommend that the current standard dosages used for light-breed horses can also be applied to miniature horses safely and effectively.