fenbendazole fenbendazole fenbendazole is a broad spectrum benzimidazole anthelmintic used against gastrointestinal parasites including: giardia, roundworms, hookworms, whipworms, the tapeworm genus taenia (but not effective against dipylidium caninum, a common dog tapeworm), pinworms, aelurostrongylus, paragonimiasis, strongyles, and strongyloides that can be administered to sheep, cattle, horses, fish, dogs, cats, rabbits, most reptiles, freshwater shrimp tanks as planaria and hydra treatments, as well as seals. fenbendazoleclinical dataahfs/drugs.cominternational drug nameslicense data us dailymed: fenbendazole atc codep02ca06 (who) qp52ac13 (who)identifiers iupac name methyl n-(6-phenylsulfanyl-1h-benzoimidazol-2-yl)carbamate cas number43210-67-9 ypubchem cid3334chemspider3217 yunii621bvt9m36keggd04140 ychebichebi:77092 nchemblchembl37161 ycomptox dashboard (epa)dtxsid0040672 echa infocard100.051.024 chemical and physical dataformulac15h13n3o2smolar mass299.35 g·mol−13d model (jsmol)interactive image smiles coc(=o)nc3nc2ccc(sc1ccccc1)cc23 inchi inchi=1s/c15h13n3o2s/c1-20-15(19)18-14-16-12-8-7-11(9-13(12)17-14)21-10-5-3-2-4-6-10/h2-9h,1h3,(h2,16,17,18,19) ykey:hddshpaodjukpd-uhfffaoysa-n y ny (what is this?) (verify) drug interactions drug interactions may occur if salicylanilides such as dibromsalan and niclosamide are co-administered. abortions in cattle and death in sheep have been reported after using these medications together. abortions in domestic ruminants have been associated with concurrent use of anti-trematode therapeutic agents. toxicity fenbendazole is poorly absorbed from the gastrointestinal tract in most species. the ld50 in laboratory animals exceeds 10 g/kg when administered orally. metabolism fenbendazole is metabolized in the liver to oxfendazole, which is anthelmintic too; oxfendazole partially gets reduced back to fenbendazole in the liver and rumen. also, fenbendazole itself is an active metabolite of another anthelmintic drug, febantel.