Fenbendazole is a broad-spectrum antiparasitic drug used in the treatment of intestinal helminth parasites and nematodes in many species. It has also been shown to have antitumor effects. Glucose uptake is an important characteristic of tumor cells, and fenbendazole inhibits glucose uptake by cancer cells. Thus, fenbendazole may provide an effective chemotherapeutic agent for treating malignant neoplasms.
Currently, fenbendazole is not FDA approved for use in medicated feed for captive pheasants (Sporochrome trachea). However, it is administered in this manner on an extra-label basis because of its efficacy against helminths and other parasites in these birds. In fact, fenbendazole has demonstrated higher efficacy against a number of helminths in pheasants than the early generation benzimidazoles and other similar drugs.
These results are consistent with the known antitumor effects of fenbendazole in other animal species. In human cancer cells, fenbendazole has been shown to reduce cell viability at high concentrations by blocking cellular mitochondrial energy production. In a study that examined the effect of combining fenbendazole with the cytotoxic drug docetaxel in cultured human cancer cells, both drugs reduced the cell viability at the same concentrations and did not interact with each other. The survival curves for cells treated with fenbendazole alone or in combination with docetaxel were superimposed, showing that the drugs had additive toxicity.
Since no fenbendazole tolerance or MRL has been established for pheasants, and the metabolism of this drug in these animals is expected to be similar to that of chickens, we utilized data on chicken consumption, FDA/EMA liver residue limits, fenbendazole sulfone LODs, and EMA fenbendazole MRLs in this analysis. This resulted in a deterministic risk assessment of the potential risks to humans of consuming meat from pheasants that have been exposed to fenbendazole. fenbendazole for humans