Pharmacokinetics of single-dose oral ponazuril in weanling goats.

Ponazuril (toltrazuril sulfone) is a triazine antiprotozoal agent that targets apicomplexan organisms. Ponazuril may have clinical application in the treatment of clinical coccidiosis due to Eimeria species in goats, along with other protozoal infections. To evaluate the absorption, distribution and elimination characteristics of ponazuril in goats, a sensitive, validated high-pressure liquid chromatography and mass spectroscopy method for ponazuril in caprine plasma was developed. After a single oral dose of ponazuril at 10 mg/kg, plasma samples from seven weanling goats were collected and assayed. Plasma concentrations of ponazuril in the goats peaked at 36 ± 13 h post drug administration at a concentration of 9 ± 2 μg/mL. Concentrations declined to an average of 4.2 ± 0.8 μg/mL after 168 h with an average elimination half-life of 129 ± 72 h post drug administration. This study shows that ponazuril is relatively well absorbed after a single oral dose in goats. Efficacy trials are underway to determine clinical efficacy of ponazuril in the treatment of clinical coccidiosis in goats at 10 mg/kg dosage.