Determination of grapiprant plasma and urine concentrations in horses.

The research investigates the effects of grapiprant, a non-steroidal anti-inflammatory drug, in horses, by measuring its levels in their plasma and urine. The researchers also aimed to establish a method for analyzation of the drug levels.

Objective and Methodology

• The researchers aimed to observe if the dosage of grapiprant typically approved for dogs could yield measurable traces in horses.
• In addition, their goal was to establish a method to analyze grapiprant levels in urine and plasma.
• The experiment was conducted on six adult, mixed-breed mares. The horses were administered a dose of grapiprant.
• Both blood and urine samples were collected before and after the administration of the drug, up to 48 hours, to measure the concentration of the drug.
• The method used to measure drug concentrations was high-performance liquid chromatography – a powerful tool in analysis of organic compounds.

Findings

• The concentrations of grapiprant in the plasma of the horses varied from 71 to 149 ng/mL, with the mean peak concentration at 106 ng/mL occurring 30 minutes after administration.
• However, in four out of six horses, the concentrations were below the lower limit of quantification (50 ng/mL), one hour post-administration, and in all the horses two hours post-administration.
• Here, the lower limit of quantification refers to the lowest level of a drug that can be consistently measured.
• The concentrations of grapiprant in the urine of the horses ranged from 40 to 4077 ng/mL and were still detectable 48 hours after administration.

Conclusion

• The current study is the first of its kind that examines the pharmacodynamics (the process by which a drug acts on the body) of grapiprant in horses.
• The effective concentration of grapiprant needed to alleviate pain in dogs ranges from 114-164 ng/mL. However, the administration of grapiprant in horses, at the same dosage as for dogs, did not attain those drug concentrations.
• The dose was well tolerated by the horses, which suggests that further studies could be executed with larger doses.