Fenben lab fenbendazole (FBZ) is an anthelmintic commonly used to treat pinworm outbreaks in laboratory rodents. Because antiparasitic treatments are not usually included in experimental designs, possible interactions from fenbendazole on ongoing experiments should be carefully evaluated. FBZ is converted to the active metabolite febantel in the liver, and hepatic cytochrome P450 isoforms, notably 1A1 and 2A2, can bioactivate certain procarcinogenic compounds.
In the present study, 4-wk-old SCID mice were fed a standard diet, a diet containing fenbendazole only, a diet supplemented with both vitamins and fenbendazole, or a control diet with no fenbendazole. Tumor growth was measured by caliper at regular intervals until the largest tumor reached a calculated volume of 1500 mm3. Neither diet alone or fenbendazole treatment alone suppressed tumor growth. However, the group fed a diet supplemented with both fenbendazole and vitamins showed significant tumor suppression. This synergistic effect deserves further investigation.
2-h incubations of EMT6 cells with fenbendazole were not toxic to the culture at doses up to the limit of solubility. Survival curves exhibited a steep decrease in cell viability at the lowest drug concentration and a plateau after that point. Cell numbers in cultures treated in hypoxia were not significantly different from those of cultures treated in air.
The results of the present study are consistent with the hypothesis that vitamin concentrations in prepared diets deteriorate over time and may contribute to reduced tumor suppression. The diet used in the initial observation had an expiration date of only 6 mo, but the diet used in this experiment was a few weeks older and therefore contained lower vitamin concentrations. fenben lab fenbendazol