Influence of feeding schedule on the absorption of orally administered flunixin in the horse.

This research investigates the impact of feeding schedules on the absorption of an orally administered drug, flunixin, in ponies. The study found that the horses’ access to hay and restriction of feeding influenced the pharmacokinetic properties of flunixin, with no food intake before and after administering the drug leading to quick absorption and higher peak plasma concentration compared to when horses were fed before and after taking the drug.

Exploration of the Impact of Feeding Schedules on Pharmacokinetics of Flunixin

• The study compared the influence of two feeding conditions – access to hay and restricted feeding – on the pharmacokinetics (observation of a drug’s absorption, distribution, metabolism, and excretion in the body) of flunixin, a nonsteroidal anti-inflammatory drug (NSAID), in six healthy ponies. This comparison was set up as a cross-over study, a type of research design where participants receive different sequences of treatments or exposures over various periods.

Effects of No access to Feed before and after Flunixin Administration

• When the ponies were restricted from feed a few hours before and after flunixin administration, there was a rapid absorption of the drug, reaching a mean peak plasma concentration of 2.84 +/- 0.28 micrograms/ml. This maximum concentration was achieved in an average time of 0.76 +/- 0.18 hours.
• After reaching the peak, there was an exponential decline in the plasma concentration of flunixin, indicating rapid elimination of the drug from the body.

Impact of Access to Hay before and after Drug Dosing

• When the ponies were provided with free access to hay before and after drug dosing, the peak plasma concentration of flunixin was lower (1.30 +/- 0.23 micrograms/ml). Also, the time to reach this maximum concentration (tmax) was prolonged (7.66 +/- 1.74 hours), which means the drug took longer to reach its maximum concentration in the plasma.
• The free access to hay seemed to reduce and delay the peak plasma concentration, resulting in two or three distinct concentration peaks in some ponies, implying fluctuating plasma levels of the drug rather than a single sharp peak.

Non-significant Difference in Area Under Plasma Concentration-Time Curve

• Despite the different feeding schedules’ impacts on the absorption speed and peak plasma concentrations, the mean area under the plasma concentration-time curve was not significantly different between the two feeding schedules. The area under the curve (AUC) is a measure used in pharmacokinetics to quantify the overall drug exposure in the body. A non-significant difference in AUC suggests that the total absorption of flunixin over time was comparable between the two feeding conditions.