Pharmacotherapeutic group: Anthelmintics, phenol derivatives, including salicylanilides.
ATC Vet Code: QP52AG09
Pharmacodynamic properties
The product contains the salicylanilide closantel, a synthetic antiparasitic agent with high activity against liver fluke, haematophagous nematodes and the larval stages of some arthropods in sheep.
Closantel uncouples the mitochondrial oxidative phosphorylation resulting in inhibition of ATP synthesis. This induces a marked change in the energy metabolism of the parasite which finally kills it.
Closantel is active against benzimidazole resistant strains of Haemonchus contortus.
Pharmacokinetic particulars
Closantel is rapidly absorbed into the systemic circulation with peak plasma levels at 24-48 hours after dosing. The bioavailability of an oral dose is 50 %. In plasma, closantel is bound to albumin for more than 99 %. As a result, tissue distribution is very limited. On average, tissue levels are 15 times lower than plasma levels. The elimination half-life of closantel from plasma and tissues is approximately 2 to 4 weeks in sheep. Closantel is metabolised only to a slight extent and the main excretion route is the bile. The urinary excretion is negligible.
Environmental properties
Closantel has the potential to adversely affect non-target organisms. Following treatment, excretion of potentially toxic levels of closantel may take place over a period of several weeks. Faeces containing closantel excreted onto pasture by treated animals may reduce the abundance of dung feeding organisms which may impact on the dung degradation.