Pharmacokinetics of flunixin meglumine in healthy foals less than twenty-four hours old.

The research paper investigates the pharmacokinetics, specifically the absorption, distribution, and elimination, of the drug flunixin meglumine in foals less than 24 hours old. The results demonstrate that the mechanisms in these newborn foals differ significantly enough from adults to necessitate different dosing guidelines.

Methodology

The study involved certain steps to establish the pharmacokinetics parameters in foals.

• A total of six healthy foals, four female and two male were selected for the study. Their age ranged from 6 to 22.5 hours with a mean of 11.6 hours.
• The foals were administered the drug flunixin meglumine at a dosage of 1.1 mg/kg of body weight.
• Blood samples were taken from the foals at specific intervals over a 48-hour period following the administration of the drug. These samples were then centrifuged, and the plasma was frozen at -70°C until it was ready for analysis.
• The analysis of flunixin concentration in the plasma samples was performed with gas chromatography/mass spectroscopy and evaluated using standard pharmacokinetic techniques. This done to understand the absorption, distribution, metabolism and excretion of the drug.
• The concentration versus time profiles were subjected to one-, two-, and three-compartment analyses. Akaike’s information criterion analysis determined which model fit the data most efficiently.

Findings

The key results from the conducted studies are:

• The two-compartment open model offered the best description of plasma concentration versus time profiles for these foals.
• compared to older foals and adult horses, the clearance of the drug was significantly lower in these young foals.
• The volume of distribution was found to be larger in the infant foals than in adult horses.
• The average half-life of flunixin in the bloodstream of foals was approximately 8.5 hours.

Conclusions

The study’s findings have some considerable implications for the administration of flunixin meglumine to very young foals.

• Due to their distinct pharmacokinetics, foals less than 24 hours old need to be given this drug differently from adults.
• Considering the same clinical conditions, to get comparable therapeutic concentrations, the dosage for these foals should be increased by as much as 1.5 times more.
• Longer dosing intervals may be needed to avoid potential drug toxicity, depending on the clinical response of the individual foal.
• Other potential factors, such as dehydration or sepsis, also need to be taken into account on a case-by-case basis when determining dosing guidelines for this age group.