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.

Pyrvinium (Viprynium) is an anthelmintic effective for pinworms. Pyrvinium is used in the treatment of enterobiasis caused by Enterobius vermicularis (pinworm). Pyrvinium has being shown to be a potent inhibitor of Wnt signaling (EC(50) of ∼10 nM). Pyrvinium binds all casein kinase 1 (CK1) family members in vitro at low nanomolar concentrations and pyrvinium selectively potentiates casein kinase 1α (CK1α) kinase activity. Pyrvinium pamoate (PP) is a potent noncompetitive inhibitor of the androgen receptor (AR). A noncompetitive AR inhibitor pyrvinium has significant potential to treat CRPC, including cancers driven by ligand-independent AR signaling.

Fumagillin, an antimicrobial compound first isolated in 1949 from the fungus Aspergillus fumigatusa, naturally occurring water-insoluble antibacterial agent developed by sanofi-aventis, is approved in France for the treatment of microsporidiosis. Fumagillin (Flisint, Sanofi-Aventis, Paris, France) has been approved in France since 2002 for the treatment of intestinal microsporidiosis due to E. bieneusi in patients with AIDS, and is also available through an expanded access program for patients without AIDS. It has not been approved, however, by the US Food and Drug Administration. The discovery of fumagillin, a MetAP-2 inhibitor, with potent antiangiogenic and antiproliferative activities promoted the development of fumagillin analogues as a novel class of anticancer agents. It has been the subject of research in cancer treatments by employing its angiogenesis inhibitory properties.

Bithionol is a synthetic sulfanediyl-bis-dichlorphenol), potent photosensitizer with the potential to cause serious skin disorders, formerly marketed as an active ingredient in various topical drug products. Bithionol has antibacterial and anthelmintic properties along with algaecide activity. Bithionol has been shown to be a potent inhibitor of soluble adenylyl cyclase (sAC, Adenylate cyclase type 10 ), an intracellular enzyme important in the catalysis of ATP to cAMP. Bithionol is the first known sAC inhibitor to act through the bicarbonate binding site via a mostly allosteric mechanism. Bithionol is used for treatment of tapeworm infections of dogs, cats, and poultry and for tapeworm and rumen fluke infections of sheep, horses, cattle, and goats.

ARSTHINOL, an organoarsenical compound, is an antiprotozoal agent used for the treatment of mild or asymptomatic intestinal amebiasis. ARSTHINOL in complex with cyclodextrin displays an anticancer activity.

Lindane is an isomer of hexachlorocyclohexane that has been used both as an agricultural insecticide and as a pharmaceutical. As a shampoo, lindane is used for treamtment lice infestation. Lindane lotion is used for treatment of scabies. Due to toxicities, associated with lindane, it is used only in patients who cannot tolerate or have failed first-line treatment with safer medication. Lindane exerts its parasiticidal action by being directly absorbed into the parasites and their ova, where it interferes with GABA neurotransmitter function by interacting with the GABAA channel complex at the picrotoxin binding site.

Diethylcarbamazine is used in humans, dogs and cats for the treatment of parasitic infections, including pulmonary eosinophilia, loiasis, and lymphatic filariasis. The exact mechanism of its action is unknown, however some studies showed the involvment of inducible nitric-oxide synthase and the cyclooxygenase pathway. Although there is no information on whether the drug is marketed in the USA and Europe, it is currently used in India.