Fenben lab fenbendazole is an anthelmintic (a drug that kills parasites) commonly used in dogs, cats and horses to treat various gastrointestinal parasites including pinworms, giardia, roundworms, hookworms, whipworms and Taenia solium. It also has antitumor activity and binds to the microtubules in cancer cells to destabilize them, thereby causing cell death. It is similar to hypoxia-selective nitroheterocyclic cytotoxic agents and taxanes, which have been shown to be effective in human tumor cells.
We recently encountered a female patient who presented to our clinic with progressive abdominal pain, elevated serum CEA levels and a positive MRI scan. During the course of her evaluation, it was discovered that she had been taking oral fenbendazole (Fenben Labs brand) for several months. Her pembrolizumab monotherapy was subsequently temporarily suspended due to this adverse reaction, which was thought to be immune-related and related to her liver injury.
Febendazole is a moderate microtubule-destabilizing agent with antitumor activity and exhibits additive toxicity when combined with radiation or taxanes in solid tumors. The drug acts as a binds to b-tubulin, which prevents the polymerization of tubulin molecules that make up the microtubules that give shape and support to cells. It also inhibits cyclin-dependent kinases and halts cell growth by blocking mitosis.
The toxic effects of fenbendazole in several species of avian have been described as characterized by multiple episodes of leukopenia associated with bone marrow hypoplasia and intestinal crypt cell necrosis. The pharmacokinetics of this compound in birds are well documented, and its metabolic and renal excretory pathways have been studied in some detail. Similar toxicity of the diclofenac analogue etotac methyl in Cape Griffons (Gyps coprotheres) and White-backed Vultures (Gyps africanus) and Lappet-faced Vultures (Torgos tracheliotus) has been reported, highlighting potential metabolic similarities between these species that may explain their susceptibility to fenbendazole. fenben lab fenbendazol