Fasciolicidal not only against the adult worms present in the biliary ducts, but also against the immature larval stages of Fasciola migrating through the hepatic parenchyma; the mechanism of action is not thoroughly understood; however, triclabendazole is shown to penetrate into liver flukes by transtegumentary absorption followed by inhibition of the parasite's motility, probably related to the destruction of the microtubular structure, resulting in the death of the parasite; the immobilizing effect is paralleled by changes in the parasite's resting tegumental membrane potential, strongly inhibiting the release of proteolytic enzymes, a process that appears critical to the survival of the parasite