Inhibition of platelet function with clopidogrel, as measured with a novel whole blood impedance aggregometer in horses.

The research article is about an experiment conducted to validate clopidogrel dosage for inhibiting platelet function in horses, using a special blood impedance aggregometer.

Explanation of the Study

This study intended to confirm the validity of using clopidogrel, a platelet inhibition medication, in horses. Ten adult Warmblood horses were given oral clopidogrel daily. The dosage was calculated based on the horses’ weight class, with a single loading dosage followed by maintenance doses over the next four days:

• The initial loading dose was 6-6.5 mg/kg of the horse’s body weight.
• The maintenance doses given over the subsequent four days ranged between 1.2-1.4 mg/kg.

Measurement and Analysis

The platelet function was assessed using whole blood multiple electrode impedance aggregometry at different time intervals:

• Before administering the drug (T0).
• At 6, 12, 24, 48, 72, 96, 144, 192, and 240 hours after the loading dose.

Four aggregometry tests were administered to ascertain platelet function. The tests were for:

• Collagen (COLtest).
• Arachidonic acid (ASPItest).
• Adenosine diphosphate (ADPtest).
• ADP with prostaglandin E1 (ADPtestHS).

For statistical analysis, the study employed one way repeated measures ANOVAs (Analysis of Variance) followed by Dunnett’s tests.

Results of the Study

The ability of the horse’s platelets to aggregate due to collagen remained the same throughout the experiment. However, there were significant reductions in the ASPItest and the ADPtest and ADPtestHS, except at the 240-hour mark.

The researchers found that the initial dosage of clopidogrel produced a swift inhibition to platelet functionality within a few hours and the low maintenance dose was sufficient to maintain this inhibited state over the four days of treatment. Platelet function was restored six days after the treatment stopped, as shown by the ADPtest and ADPtestHS, but remained inhibited according to the ASPItest.

Conclusions of the Study

The lasting effect of clopidogrel could suggest a difference in how platelets activate between horses and humans, something that previously was not known.