Serum concentrations of trimethoprim and sulfadiazine following oral paste administration to the horse.

The researchers investigated how the horse’s body absorbs and processes the orally administered drugs trimethoprim and sulfadiazine. They found that the absorption rates vary, but both drugs reached concentrations in the horse’s bloodstream that could be effective against common pathogens in horses.

Study Design and Execution

• The researchers carried out this study using four horses, two of which were fed and the other two fasted.
• These horses were given a paste formulation that combined the drugs trimethoprim and sulfadiazine. The dose delivered was 35 mg per kg of horse weight, maintaining a 1:5 ratio of the active ingredients.
• The serum concentrations of each drug in the bloodstream were checked periodically for three consecutive days to monitor the absorption and effectiveness of the drugs.

Findings and Interpretations

• The absorption of trimethoprim in the horse’s body showed variability and its peak concentration in the serum generally occurred within three hours.
• Sulfadiazine, on the other hand, exhibited slower absorption, with its peak concentrations reached by six hours.
• Fasting or feeding the horses, did not consistently affect the serum concentration profiles for either of the administered drugs, indicating that the absorption of these drugs is not significantly influenced by the feeding status of the horse.
• importantly, the serum concentrations of both drugs in the horses reached or exceeded the minimum inhibitory concentrations. This means that the levels of the drugs were sufficient to inhibit the growth and activity of certain pathogens, bacteria or microorganisms that commonly cause illnesses in horses.
• As such, the findings suggest that the paste formulation is an effective means of administering these drugs to horses.