Closantel is a synthetic anti parasitic agent which is highly effective against adults and larvae (6 to weeks old) of liver flukes (Fasciola hepatica), and against several important gastrointestinal roundworms (e.g. Bunostomum, Haemonchus, Oesophagostomum, Ostertagia - Teladorsagia, Strongyloides, Trichostrongylus), as well as against screwworms (maggots of Cochliomyia spp and Chrysomya spp), sheep nasal bots (Oestrus ovis), and sheep keds (Melophagus ovinus). The molecular mode of action closantel is not completely elucidated, but closantel decouples the mitochondrial oxidative phosphorylation, which leads to the inhibition of ATP synthesis, this seems to occur through suppression of the activity of succinate dehydrogenase and fumarate reductase, two enzymes involved in this process. Finally this all cause the death of the parasite. Recently it has been discovered that closantel also inhibits chitinase in Onchocerca volvulus, a filarial nematode causing river blindness in humans. Chitinase is an enzyme involved in larval molting. Its inhibition interrupts their development to adult worms. This drug possesses some side effects: hyper acute anaphylactic reactions in cattle; hypersensitivity reactions; overdoses can cause reduced visibility or blindness, anorexia, lack of coordination and general weakness.

Bromofenofos is an anthelminthic agent used in veterinary medicine to treat common liver fluke (Fasciola hepatica) infections in cattle and sheep.

Thiacetarsamide is a drug containing trivalent arsenic. In the USA it was used for the treatment of Heartworm Infection in dogs and cats under tradename Caparsolate, however, it was discontinued because of the availability of safer alternatives. The mechanism of action for thiacetarsamide is modulation of glucose uptake and metabolism; inhibition of glutathione reductase, and alteration of the structure and function of the surface of the intestinal epithelium of the parasites.

Parbendazole is a potent inhibitor of microtubule assembly that was studied as an anthelmintic agent. Information about the current use of this drug is not available.

Destomycin A is an aminoglycoside antibiotic and is reported to have antibacterial and anthelmintic activity. It has an antibacterial effect on Gram-positive bacteria, Gram-negative bacteria, and fungi. The mode of action of destomycin A is the inhibition of polypeptide synthesis in cells of Escherichia coli and stimulation of adenylate cyclase in several animal tissues. Destomycin A is added to feed for pigs and chickens to prevent parasitic infection of Ascaris suum (the mechanism of action involves inhibition of vitelline coat formation of the parasite eggs.)

Levamisole (the trade name Ergamisol), an anthelminthic drug with immunological properties. It also has antitumor activity when administered with 5-fluorouracil in patients with Duke's C colorectal carcinoma; however, this use was discontinued. The mechanism of the antitumor effect is unknown but has been postulated to be related to levamisole's immunomodulatory properties. Levamisole can stimulate antibody formation to various antigens, enhance T-cell responses by stimulating T-cell activation and proliferation, potentiate monocyte and macrophage functions including phagocytosis, chemotaxis and increases motility, adherence, and chemotaxis. Levamisole inhibits alkaline phosphatase and possesses cholinergic activity. The mechanism of action of levamisole as an antiparasitic agent, for example, to treat ascariasis, relates to its agonistic activity to L-subtype nicotinic acetylcholine receptors in nematode muscles. In addition, levamisole was studied for preventing relapses of the steroid-sensitive idiopathic nephrotic syndrome (SSINS). It was shown, that alone or in combination with steroids, the drug can prolong the time to relapse and prevented recurrence during one year of treatment. However, these studies also were also discontinued.

Niclosamide is an antihelminth used against tapeworm infections. It may act by the uncoupling of the electron transport chain to ATP synthase. The disturbance of this crucial metabolic pathway prevents creation of adenosine tri-phosphate (ATP), an essential molecule that supplies energy for metabolism. Niclosamide works by killing tapeworms on contact. Adult worms (but not ova) are rapidly killed, presumably due to uncoupling of oxidative phosphorylation or stimulation of ATPase activity. The killed worms are then passed in the stool or sometimes destroyed in the intestine. Niclosamide may work as a molluscicide by binding to and damaging DNA. Niclosamide is used for the treatment of tapeworm and intestinal fluke infections: Taenia saginata (Beef Tapeworm), Taenia solium (Pork Tapeworm), Diphyllobothrium latum (Fish Tapeworm), Fasciolopsis buski (large intestinal fluke). Niclosamide is also used as a molluscicide in the control of schistosomiasis. Niclosamide was marketed under the trade name Niclocide, now discontinued.

Oxamniquine is an anthelmintic with schistosomicidal activity against Schistosoma mansoni, but not against other Schistosoma spp. Oxamniquine is a potent single-dose agent for treatment of S. mansoni infection in man, and it causes worms to shift from the mesenteric veins to the liver, where the male worms are retained; the female worms return to the mesentery, but can no longer release eggs. Oxamniquine is a semisynthetic tetrahydroquinoline and possibly acts by DNA binding, resulting in contraction and paralysis of the worms and eventual detachment from terminal venules in the mesentry, and death. Its biochemical mechanisms are hypothesized to be related to an anticholinergic effect, which increases the parasite’s motility, as well as to synthesis inhibition of nucleic acids. Oxamniquine acts mainly on male worms, but also induces small changes on a small proportion of females. Like praziquantel, it promotes more severe damage of the dorsal tegument than of the ventral surface. The drug causes the male worms to shift from the mesenteric circulation to the liver, where the cellular host response causes its final elimination. The changes caused in the females are reversible and are due primarily to the discontinued male stimulation rather than the direct effect of oxamniquine

Thiabendazole (TBZ, trade names Mintezol, Tresaderm, and Arbotect) was first introduced in 1962. This drug is a fungicide and parasiticide and is indicated for the treatment of: strongyloidiasis (threadworm), cutaneous larva migrans (creeping eruption), visceral larva migrans, trichinosis: relief of symptoms and fever and a reduction of eosinophilia have followed the use of this drug during the invasion stage of the disease. But usage of this drug was discontinued. The precise mode of action of thiabendazole on the parasite is unknown, but it may inhibit the helminthspecific enzyme fumarate reductase. It was shown, also that thiabendazole reversibly disassembles newly established blood vessels, marking it as vascular disrupting agent (VDA) and thus as a potential complementary therapeutic for use in combination with current anti-angiogenic therapies. Was shown, that vascular disruption by TBZ results from reduced tubulin levels and hyper-active Rho signaling. In addition, was confirmed, that thiabendazole slowed tumor growth and decreased vascular density in preclinical fibrosarcoma xenografts and thus, it could lead directly to the identification of a potential new therapeutic application for an inexpensive drug that is already approved for clinical use in humans.