Fenben

Fenbendazole is effective for treatment of numerous helminth intestinal parasites in animals, including Toxocara, Toxascaris, Ancylostoma, and Trichuris spp. In dogs, it is effective for most intestinal helminth parasites and against nematodes. In dogs, it also has been used for pulmonary helminths (lungworms), but a longer duration of treatment is needed. Fenbendazole has been effective for treatment of Giardia infection, but higher doses are needed and there may be failure rates as high as 50%. It is effective in cats for treatment of lungworms, flukes, and a variety of helminth parasites. In horses, it is used for the control of large strongyles, small strongyles, pinworms, and ascarids. In pigs, it is effective for lungworms, large roundworms, nodular worms, small stomach worms, and kidney worms. In beef and dairy cattle, it is effective for control of lungworms, stomach worms, barberpole worms, stomach worms, and various intestinal worms.

Fenbendazole is a benzimidazole antiparasitic drug. Like other benzimidazoles, fenbendazole produces a degeneration of the parasite microtubule and irreversibly blocks glucose uptake in parasites. Inhibition of glucose uptake causes depletion of energy stores in the parasite, eventually resulting in death. Mammals are spared from adverse effects because there is no effect on glucose metabolism in mammals.

BROMSALAN FLUKICIDES (dibromsalan, tribromsalan): Oxfendazole or fenbendazole should not be given concurrently with the bromsalan flukicides; abortions in cattle and death in sheep have been reported after using these compounds together

Fenbendazole has a good safety margin, but vomiting and diarrhea have been reported. When evaluated at doses of three and five times the recommended dose at three times the recommended duration, fenbendazole was well tolerated, and no adverse effects were reported in the target species.

Fenbendazole is apparently well tolerated at doses up to 100X recommended.
The LD50 in laboratory animals exceeds 10 grams/kg when administered PO. It is unlikely an acute overdosage would lead to clinical signs.

 It has been safe to use during pregnancy. There have been reports of pancytopenia associated with fenbendazole administration, but these are rare.

Meat: 14 days.

Milk: 3 days