Diclazuril nonlinear mixed-effects pharmacokinetic modelling of plasma concentrations after oral administration to adult horses every 3-4 days.

The research study examines if a small dosage of diclazuril, administered to horses every 3-4 days, could achieve a steady plasma concentration that is known to inhibit the growth of diseases caused by Sarcocystis neurona and Neospora caninum.

Objective of the Research

• The aim of this study was to understand if administering a low dose of diclazuril at periodic intervals could lead to achieving a steady plasma concentration enough to inhibit two specific diseases – Sarcocystis neurona and Neospora caninum, both of which are harmful to horses.

Details of the Study

• In order to measure the pharmacokinetics of diclazuril, the researchers experimentally administered low doses of diclazuril (0.5 mg/kg of 1.56% diclazuril pellets) to six healthy adult horses every 3-4 days.
• The experiment extended over five administrations in order to gauge the drug’s capacity to reach steady-state plasma concentrations within this interval.

Methodology and Results

• To monitor the drug levels, blood was collected from the horses before (baseline concentrations) and 10 hours after (peak concentrations) each diclazuril administration.
• The analysis of the plasma samples was executed by high-pressure liquid chromatography, a technique often applied for separating, identifying, and quantifying each component in a mixture.
• The mean population-derived peak concentration was reportedly 0.284μg/mL and the mean terminal half-life was 1.6 days.
• The study discovered the presence of large variations in the terminal half-life, hinting at the individual variations in the horses’ metabolism and absorption of the drug.

Conclusions

• From the results, it was concluded that the low dose of diclazuril pellets can indeed produce stable plasma drug concentrations known to prevent the proliferation of S. neurona (0.001μg/mL) and N. caninum (0.1μg/mL).
• This implies that a strategic and controlled administration of diclazuril could be potent in preventing these horse diseases caused by these two specific parasites.