Fenben lab fenbendazole is a broad-spectrum benzimidazole antihelmintic that acts by binding to the cell cycle regulatory proteins and interfering with their dimerization into microtubules. This disrupts normal cellular functions, including protein synthesis and cell division, in nematodes and other parasites, causing their death (Martin 1997). It is highly selective for the b-tubulins of nematode cells, as well as those of mammalian cells, and does not affect a-tubulins.
The drug has been shown to be effective in treating numerous gastrointestinal parasites and cestodes, including the tapeworm genus Taenia (but not Dipylidium caninum, a common dog tapeworm), giardia, hookworms, whipworms, pinworms, hydatid cysts, and stomach flukes. It also has been demonstrated to be efficacious against trematodes such as Mesocestoides spp. tetrathyridial infection in cattle, and strongyloides such as Heterobilharzia americana and Paragonimus kellicotti.
Cell culture studies of fenbendazole in combination with radiation or the hypoxia-selective nitroheterocyclic cytotoxic/radiosensitizer docetaxel, using EMT6 mammary tumor cells grown as solid tumors in mice, showed additive toxicity. The toxicity of fenbendazole was independent of the incubation time and concentration in hypoxia. In addition, fenbendazole in maximally intensive regimens did not alter the dose-response curve for radiation or increase the antineoplastic activity of docetaxel against these tumors.
Because Gyps vultures are obligate scavengers that typically feed on livestock carcasses, long-term exposure to residual fenbendazole could lead to reduced bone marrow function and/or adverse effects on gut mucosa and consequently reduce the fitness of vultures for this life history. This fenbendazole toxicity has not been demonstrated in Gyps vultures exposed to livestock carcasses, however, and a number of studies have reported that fenbendazole does not affect the growth of unirradiated tumors in mice. fenben lab fenbendazol