A benzimidazole anthelmintic; active against a variety of helminths, including liver flukes, tapeworms, and roundworms; eliminates Trichostrongylus in the fourth stomach of cattle and sheep (2.5-10 mg/kg) as well as other species; protects mice against lethal infection with A. suum larvae (0.05% in the diet); inhibits growth of HT-29 human colorectal cancer cells (IC50 = 0.12 μM), halts the cell cycle at the G2/M phase, and induces apoptosis; inhibits peritoneal tumor growth in an HT-29 mouse xenograft model (150 mg/kg, i.p.); inhibits mammalian tubulin polymerization and inhibits binding of [3H]mebendazole to H. contortus L3 larval tubulin (IC50s = 6.9 and 0.21 μM, respectively)