Fenbendazole is a broad spectrum benzimidazole anthelmintic that is used to treat and/or prevent gastrointestinal parasites, such as giardia in dogs, roundworms, hookworms, whipworms, the tapeworm genus Taenia, pinworms, aelurostrongylus, and lungworms in cats. It is also effective against nematodes and protozoal infections. It is safe for use in pregnant and nursing animals, though a higher dosage is required in cats.
The pharmacological properties of fenbendazole have recently been extended to investigate its effects on cancer. In a series of experiments, EMT6 cancer cells were treated with varying concentrations of fenbendazole for 24 h and then assayed for cell survival in a colony formation assay. The results of these studies showed that fenbendazole had cytotoxic as well as cytostatic effects on the cells.
These effects were investigated further using three different i.p. injections of fenbendazole in BALB/c mice with EMT6 tumors. When the tumors had reached a mean volume of approximately 1000 mm3, they were randomly assigned to treatment groups, which received either no fenbendazole (control), low dose fenbendazole (5 mg/kg/day), or high dose fenbendazole (20 mg/kg/day). At each time point, the duration of the growth of the tumor from its initial volume to four-times that size was rigorously evaluated. Neither the low or high concentrations of fenbendazole impacted the growth rate of unirradiated tumors. However, irradiation of tumors in the presence of fenbendazole reduced their growth rates by about one third.
Although fenbendazole is not approved by the FDA for deworming of dogs or cats, it is a common and very safe medication that is used off label to control intestinal parasites in these pets. It is a slow kill drug, which reduces the likelihood of obstruction as the worms die in the digestive tract. It is often recommended in conjunction with other anthelmintics to treat the most severe cases of intestinal parasites.
The medication comes in a capsule form and is given orally. It can be crushed and mixed with food to reduce gastrointestinal upset. It is generally well-tolerated by pets and typically has no serious side effects, but it can cause vomiting in some animals. A fecal examination should be performed after deworming to determine if all the worms have been eliminated from the pet’s system. Your veterinarian may recommend routine testing on your pet while it is taking this medication, depending on other medications the animal is taking and the issue that led to the prescription of fenbendazole. Your veterinarian can prescribe a compounded form of the medication if there is a reason it cannot be prescribed as an FDA-approved drug, such as if your pet has difficulty swallowing pills or if their medical condition requires a higher or lower dosage than what is commercially available. This type of medication is created by a veterinarian or licensed pharmacist on an individual basis to best meet your pet’s needs. fenbendazole capsules