Pharmacotherapeutic group: Antiprotozoals; triazines; toltrazuril. ATCvet code: QP51AJ01
Toltrazuril is a triazinon derivative. It acts against coccidia of the genus Isospora. It acts against all intracellular development stages of coccidia of the merogony (asexual multiplication) and gamogony (sexual phase). All stages are destroyed, thus the mode of action is coccidiocidal.
Pigs: After oral administration of the product in pigs, toltrazuril is slowly absorbed with a bioavailability of ≥ 70%. The maximum concentration (Cmax) of toltrazuril is 14 µg/mL and is obtained after around 30 h after a single oral dose of 20 mg/kg bw. The main metabolite is characterized as toltrazuril sulfone. The elimination of toltrazuril is slow with a half-life elimination time around 3 days. The major route of excretion is via the faeces.
Cattle: After oral administration of the product in cattle toltrazuril is slowly absorbed. The maximal plasma concentration (Cmax = 41.4 mg/l) was observed between 6.00 and 48 hours (mean 19 hours) following a single oral dose of 15 mg/bw. The elimination of toltrazuril is slow with a terminal half-life time of approximately 2.7 days (64.15 hours). The main metabolite is characterised as toltrazuril sulfone. The major route of excretion is via the faeces.
Sheep: After oral administration of the product in lambs, toltrazuril is slowly absorbed. The main metabolite is characterised as toltrazuril sulfone. The maximal plasma concentration (Cmax = 64.6 mg/L) was observed between 12 and 120 hours (mean 27 hours) following a single oral dose of 20 mg/bw. The elimination of toltrazuril is slow with an elimination half-life time of up to 9 days (mean 5 days). The major route of excretion is via the faeces.
Environmental properties
The metabolite of toltrazuril, toltrazuril sulfone (ponazuril) is a persistent (half-life >1 year) and mobile compound and has adverse effects on both the growth and emergence of plants. Given the persistent properties of ponazuril, repeated spreading of manure from treated animals may lead to an accumulation in the soil and consequently a risk to plants. The accumulation of ponazuril in soil together with its mobility also leads to a risk of leaching to groundwater.