Benzimidazole antiparasitic agents have a broad spectrum of activ-
ity against a variety of pathogenic internal parasites. In susceptible
parasites, their mechanism of action is believed due to disrupting
intracellular microtubular transport systems by binding selectively
and damaging tubulin, preventing tubulin polymerization, and in-
hibiting microtubule formation. Benzimidazoles also act at higher
concentrations to disrupt metabolic pathways within the helminth,
and inhibit metabolic enzymes, including malate dehydrogenase
and fumarate reductase.