Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. They may also be called vermifuges (those that stun) or vermicides (those that kill). Anthelmintics are used to treat people who are infected by helminths, a condition called helminthiasis. These drugs are also used to treat infected animals.
Pills containing anthelmintics are used in mass deworming campaigns of school-aged children in many developing countries. For example, the treatment of choice for soil-transmitted helminths is mebendazole and albendazole and praziquantel for schistosomiasis.
Antiparasitics that specifically target Ascaris worms are called ascaricides.
Benzimidazoles:
Albendazole – effective against threadworms, roundworms, whipworms, tapeworms, hookworms
Mebendazole – effective against pinworms, roundworms and hookworms
Thiabendazole – effective against roundworms, hookworms
Fenbendazole – effective against gastrointestinal parasites
Triclabendazole – effective against liver flukes
Flubendazole – effective against most intestinal parasites
Abamectin – effective against most common intestinal worms, except tapeworms, for which praziquantel is commonly used in conjunction with abamectin
Diethylcarbamazine – effective against Wuchereria bancrofti, Brugia malayi, Brugia timori, tropical pulmonary eosinophilia, loiasis
Ivermectin – effective against most common internal parasites (except tapeworms)
Suramin – It is used for treatment of human sleeping sickness caused by trypanosomes
Pyrantel pamoate – effective against most nematode infections
Levamisole
Salicylanilides:
Niclosamide – effective against tapeworms
Nitazoxanide – effective in vitro against a wide range of helminths with clinical efficacy against Ascaris lumbricoides, and Cyclospora cayetanensisOxyclozanide – effective against liver flukes
Praziquantel – effective against cestodes (i.e., tapeworms), some trematodes
Octadepsipeptides (e.g.: Emodepside) – effective against a variety of gastrointestinal helminths
Aminoacetonitrile derivatives e.g., Monepantel : effective against a variety of gastrointestinal roundworms including those resistant to other anthelmintic classes
Spiroindoles (e.g., derquantel): effective against a range of gastrointestinal roundworms including those resistant to other anthelmintic classes
Pelletierine sulphate effective against diverse tapeworms, ring worms and nematodes.
The ability of parasites to survive treatments that are generally effective at the recommended doses is a major threat to the future control of worm parasites in small ruminants and horses. This is especially true of nematodes, and has helped spur development of aminoacetonitrile derivatives for treatment against drug-resistant nematodes, as well as exploration of antibiotics use against their endosymbiotic Wolbachia bacteria.
The resistance is measured by the "fecal egg count reduction" value which varies for different types of helminths.
Treatment with an antihelminthic drug kills worms whose phenotype renders them susceptible to the drug, but resistant parasites survive and pass on their "resistance" genes. Resistant varieties accumulate and finally treatment failure occurs.
