Effect of feeding on the fate of orally administered phenylbutazone, trimethoprim and sulphadiazine in the horse.

This research focuses on how feeding affects the absorption and effectiveness of three drugs – phenylbutazone, sulphadiazine and trimethoprim – administered orally to horses. The study found that feeding prior to administration decreased the effectiveness of phenylbutazone and trimethoprim, but didn’t significantly impact sulphadiazine.

Experimental setup

• Three horses were selected as subjects for the study.
• Each horse was administered a dose of all three drugs, phenylbutazone, sulphadiazine and trimethoprim, on two separate occasions. Once when they were recently fed, and once when they were unfed.
• The severity or relative lack of food intake prior to administering the drugs was the primary variable under investigation.

Results

• The research found that the mean peak concentrations of phenylbutazone and trimethoprim in the horses’ bodies significantly reduced when they were fed prior to administration.
• Phenylbutazone’s effectiveness reduced by 34% when horses were fed, while trimethoprim saw a 75% reduction.
• In contrast, feeding did not significantly affect the pharmacokinetics, the movement of drugs within the body, of sulphadiazine.

Conclusion

• This study provides significant insights into the administration of these three drugs in horses and advises veterinarians to consider the feeding status of the horse before prescribing these medications.
• A better understanding of these effects can lead to better dosing schedules and more effective use of these drugs for treating equine diseases, reducing potential side effects and making treatments more cost-effective.