In vitro and in vivo binding of phenylbutazone and related drugs to equine feeds and digesta.

The research investigates how the drug phenylbutazone, and other related non-steroidal anti-inflammatory drugs (NSAIDs), interact with horse feed and digestive materials, both in controlled laboratory conditions and in the living organism. This understanding can provide insights into the effectiveness and behavior of such drugs in equine healthcare.

Research Methodology

• The research incorporated both in vitro (outside of a living organism) and in vivo (within a living organism) studies.
• In the in vitro experiments, binding of phenylbutazone to chopped hay and powdered pony nuts in buffer solutions was tested.
• The influence of time, concentration, and pH on drug binding were analyzed.
• In comparison to phenylbutazone, other NSAIDs like meclofenamate and flunixin were also tested for their level of binding to hay.
• The in vivo part of the research involved collecting digesta (digested or partially digested food in the intestines) from eight different regions of the horse’s gastrointestinal tract and analyzing the level of phenylbutazone binding to them.
• Ponies were administered orally with phenylbutazone to further understand its absorption and distribution in the equine digestive system.

Key Findings

• It was found that phenylbutazone binding to horse feed materials in vitro was dependent on various factors: its binding increased with time, decreased with concentration, and varied with the pH of the buffer solution.
• When compared to phenylbutazone, other NSAIDs like meclofenamate and flunixin showed lesser degrees of binding to hay.
• In vivo, phenylbutazone was found to bind extensively to digesta from various parts of the digestive tract. The highest percentage of binding was seen in the stomach (99.6%) and the lowest in the duodenum (80.0%).
• Phenylbutazone administered orally to ponies was also found to bind with the digesta.

Conclusion and Clinical Significance

• The researchers concluded that the absorption and distribution of phenylbutazone in the equine digestive system likely involve adsorptive and desorptive processes.
• Understanding drug interaction with horse feed and digesta can help optimize drug effectiveness and potentially minimize side effects in equine medicine. The study sheds light on the variable binding and absorption principles of NSAIDs, which could influence decisions about drug selection, dosage, and administration in equine healthcare.