Fenbendazole

Fenbendazole is a broad-spectrum benzimidazole anthelmintic used against gastrointestinal parasites including: roundworms, hookworms, whipworms, the tapeworm genus Taenia (but not effective against Dipylidium caninum, a common dog tapeworm), pinworms, Aelurostrongylus spp., 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, and seals.

It has not been tested or approved for use in humans by the FDA or EMA. Related benzimidazole drugs such as mebendazole and albendazole are used in humans.

Some laboratory research has shown promising results for fenbendazole and mebendazole as anticancer drugs. Exaggerated information has circulated on social media promoting fenbendazole as a miracle cancer cure. However, the possible use of fenbendazole against cancer is still at the stage of very early laboratory research, and should not be attempted without a doctor's approval and supervision. Misuse of fenbendazole can cause liver damage.

Fenbendazole works by binding to tubulin, a protein that is part of the microtubules in the cells of parasites. This binding disrupts the microtubules' formation and function, leading to the parasites' inability to absorb nutrients, resulting in their eventual death. This mode of action makes fenbendazole effective against both adult and larval stages of many parasitic worms.

Fenbendazole is commonly used to treat intestinal parasites, including roundworms, hookworms, whipworms, and certain tapeworms. It is often administered as part of a broader deworming protocol.

In equine medicine, fenbendazole is used to control strongyles, pinworms, and ascarids. It is available in paste form for easy administration.

Fenbendazole is effective against lungworms, stomach worms, and intestinal worms in ruminants. It is administered through feed, drenching, or bolus form.

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 antitrematode therapeutic agents.