Anthelmintic
Encyclopedia
Anthelmintics or antihelminthics are drugs that expel parasitic worm
s (helminths) from the body, by either stunning or killing them. They may also be called vermifuges (stunning) or vermicides (killing).
The clinical definition of resistance is a 95% or less reduction in a "Fecal Egg Count" test.
Treatment with an antihelminthic drug kills worms whose phenotype renders them susceptible to the drug.
Worms that are resistant survive and pass on their "resistance" genes.
Resistant worms accumulate and finally treatment failure occurs. See drug resistance
.
Worm
The term worm refers to an obsolete taxon used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm. Currently it is used to describe many different distantly-related animals that typically have a long cylindrical...
s (helminths) from the body, by either stunning or killing them. They may also be called vermifuges (stunning) or vermicides (killing).
Pharmaceutical classes
- Benzimidazoles:
- AlbendazoleAlbendazoleAlbendazole, marketed as Albenza, Eskazole, Zentel and Andazol, is a member of the benzimidazole compounds used as a drug indicated for the treatment of a variety of worm infestations. Although this use is widespread in the United States, the U.S. Food and Drug Administration has not approved...
– effective against threadworms, roundworms, whipworms, tapeworms, hookworms - MebendazoleMebendazoleMebendazole or MBZ is a benzimidazole drug developed by Janssen Pharmaceutica and marketed as Vermox, Ovex, Antiox, and Pripsen...
– effective against pinworms, roundworms and hookworms - ThiabendazoleThiabendazoleTiabendazole is a fungicide and parasiticide.-Fungicide:...
– effective against roundworms, hookworms - FenbendazoleFenbendazoleFenbendazole is a broad spectrum benzimidazole anthelmintic used against gastrointestinal parasites including roundworms, hookworms, whipworms, the taenia species of tapeworms, pinworms, aelurostrongylus, paragonimiasis, strongyles and strongyloides and can be administered to sheep, cattle,...
– effective against gastrointestinal parasites - Triclabendazole – effective against liver flukeLiver flukeLiver flukes are a polyphyletic group of trematodes .Adults of liver flukes are localized in the liver of various mammals, including humans. These flatworms can occur in bile ducts, gallbladder, and liver parenchyma. They feed on blood...
s - FlubendazoleFlubendazoleFlubendazole is an anthelmintic. Its brand name is Flutelmium which is a paste manufactured by Janssen Pharmaceutica N.V. used by veterinarians for protection against internal parasites and worms in dogs and cats. Other brand names are Flubenol, Biovermin, and Flumoxal....
– effective against most intestinal parasites
- AbamectinAbamectinAbamectin is a widely used insecticide and anthelmintic.-Chemistry:Abamectin is a mixture of avermectins containing more than 80% avermectin B1a and less than 20% avermectin B1b. These two components, B1a and B1b have very similar biological and toxicological properties...
– effective against most common intestinal worms, except tapeworms, for which praziquantelPraziquantelPraziquantel is an anthelmintic effective against flatworms. Praziquantel is not licensed for use in humans in the UK; it is, however, available as a veterinary anthelmintic, and is available for use in humans on a named-patient basis....
is commonly used in conjunction with abamectin - DiethylcarbamazineDiethylcarbamazineDiethylcarbamazine is an anthelmintic drug that does not resemble other antiparasitic compounds. It is a synthetic organic compound which is highly specific for several parasites and does not contain any toxic metallic elements.-Uses:...
– effective against Wuchereria bancroftiWuchereria bancroftiFilaria, is a parasitic filarial nematode spread by a mosquito vector. It is one of the three parasites that cause lymphatic filariasis, an infection of the lymphatic system by filarial worms. It affects over 120 million people, primarily in Africa, South America, and other tropical and...
, Brugia malayiBrugia malayiBrugia malayi is a nematode , one of the three causative agents of lymphatic filariasis in humans. Lymphatic filariasis, also known as elephantiasis, is a condition characterized by swelling of the lower limbs. The two other filarial causes of lymphatic filariasis are Wuchereria bancrofti and...
, Brugia timoriBrugia timoriBrugia timori is a human filarial parasitic nematode which causes the disease "Timor filariasis." While this disease was first described in 1965, the identity of Brugia timori as the causative agent was not known until 1977...
, tropical pulmonary eosinophiliaEosinophiliaEosinophilia is a condition in which the eosinophil count in the peripheral blood exceeds 0.45×109/L . A marked increase in non-blood tissue eosinophil count noticed upon histopathologic examination is diagnostic for tissue eosinophilia. Several causes are known, with the most common being...
, loiasis - NiclosamideNiclosamideNiclosamide is a teniacide in the anthelmintic family especially effective against cestodes that infect humans...
– effective against tapeworms - Ivermectin – effective against most common intestinal worms (except tapeworms)
- SuraminSuraminSuramin is a drug developed by Oskar Dressel and Richard Kothe of Bayer, Germany in 1916, and is still sold by Bayer under the brand name Germanin.According to the National Cancer Institute there are no active clinical trials...
- Pyrantel pamoatePyrantel pamoatePyrantel pamoate or Pyrantel Embonate , is used as a deworming agent in the treatment of hookworms and roundworms in domesticated animals such as horses, cattle, sheep, pigs, cats, dogs, and many other species. It is a combination of pyrantel and pamoic acid...
– effective against most nematode infections - LevamisoleLevamisoleLevamisole is an anthelminthic and immunomodulator belonging to a class of synthetic imidazothiazole derivatives. It was discovered at Janssen Pharmaceutica in 1966...
- PraziquantelPraziquantelPraziquantel is an anthelmintic effective against flatworms. Praziquantel is not licensed for use in humans in the UK; it is, however, available as a veterinary anthelmintic, and is available for use in humans on a named-patient basis....
– effective against cestodes, some trematodes - Octadepsipeptides (e.g.: EmodepsideEmodepsideEmodepside is an anthelmintic drug that is effective against a number of gastrointestinal nematodes, is licensed for use in cats and belongs to the class of drugs known as the octadepsipeptides, a relatively new class of anthelmintic , which are suspected to achieve their anti-parasitic effect by a...
) – effective against a variety of gastrointestinal helminths - AminoacetonitrileAminoacetonitrileAminoacetonitrile is a simple organic compound containing both nitrile and amino groups. It is somewhat similar to the simplest amino acid, glycine...
derivatives (e.g.: Monepantel): effective against a variety of gastrointestinal helminths including those resistant to the other drug classes.
Natural antihelmintics
Examples of naturally occurring anthelmintics include:- TobaccoTobaccoTobacco is an agricultural product processed from the leaves of plants in the genus Nicotiana. It can be consumed, used as a pesticide and, in the form of nicotine tartrate, used in some medicines...
(Nicotiana tabacumNicotiana tabacumNicotiana tabacum, or cultivated tobacco, is a perennial herbaceous plant. It is found only in cultivation, where it is the most commonly grown of all plants in the Nicotiana genus, and its leaves are commercially grown in many countries to be processed into tobacco. It grows to heights between 1...
& Nicotiana rusticaNicotiana rusticaNicotiana rustica, known in South America as Mapacho and in Vietnam as Thuoc Lao , is a plant in the Solanaceae family. It is a very potent variety of tobacco. The high concentration of nicotine in its leaves makes it useful for creating organic pesticides.Rustica is also used for entheogenic...
) - Moringa oleiferaMoringa oleiferaMoringa oleifera, the word Moringa probably came from dravidian language Tamil and commonly referred to as "Shojne" in Bengali, "Munagakaya" in Telugu,"Shenano" in Rajasthani,...
(Moringaceae) - Neem (Azadirachta indica)
- Black walnutBlack WalnutJuglans nigra, the Eastern Black walnut, is a species of flowering tree in the hickory family, Juglandaceae, that is native to eastern North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to Georgia, northern Florida and southwest to central...
(Juglans nigra) - wormwood (Artemisia absynthium)
- cloveCloveCloves are the aromatic dried flower buds of a tree in the family Myrtaceae. Cloves are native to the Maluku islands in Indonesia and used as a spice in cuisines all over the world...
(Syzygium aromaticum) - tansyTansyTansy is a perennial, herbaceous flowering plant of the aster family, native to temperate Europe and Asia. It has been introduced to other parts of the world and in some areas has become invasive...
tea (Tanacetum vulgare) - HageniaHageniaHagenia abyssinica is a species of flowering plant native to the high-elevation Afromontane regions of central and eastern Africa. It also has a disjunct distribution in the high mountains of East Africa from Sudan and Ethiopia in the north, through Kenya, Uganda, Rwanda, Burundi, Democratic...
(Hagenia abyssinica) - GarlicGarlicAllium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...
(Allium sativum) - Diatomaceous EarthDiatomaceous earthDiatomaceous earth also known as diatomite or kieselgur/kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. It has a particle size ranging from less than 1 micrometre to more than 1 millimetre, but typically 10 to...
(DE) - PineapplePineapplePineapple is the common name for a tropical plant and its edible fruit, which is actually a multiple fruit consisting of coalesced berries. It was given the name pineapple due to its resemblance to a pine cone. The pineapple is by far the most economically important plant in the Bromeliaceae...
(Ananas comosus) - kalonjiNigella sativaNigella sativa is an annual flowering plant, native to south and southwest Asia. It grows to tall, with finely divided, linear leaves. The flowers are delicate, and usually coloured pale blue and white, with five to ten petals. The fruit is a large and inflated capsule composed of three to seven...
(Nigella sativa) seeds - male fern (Dryopteris filix-mas)
- Monarda fistulosaMonarda fistulosaWild bergamot or Bee Balm is a wildflower in the mint family widespread and abundant as a native plant in much of North America. This plant, with showy summer-blooming white flowers, is often used as a honey plant, medicinal plant, and garden ornamental...
(Wild Bergamot) - HoneyHoneyHoney is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...
mixed with water and vinegar was also used as a vermifuge. - PlumeriaPlumeriaPlumeria is a genus of flowering plants of the family that includes Dogbane: the Apocynaceae. It contains 7-8 species of mainly deciduous shrubs and small trees...
(P. acutifolia or P. rubra) in Brazilian folk medicine. - Peganum harmala
- Banisteriopsis caapiBanisteriopsis caapiBanisteriopsis caapi, also known as Ayahuasca, Caapi or Yage, is a South American jungle vine of the family Malpighiaceae. It is used to prepare Ayahuasca, a decoction that has a long history of entheogenic uses as a medicine and "plant teacher" among the indigenous peoples of the Amazon Rainforest...
- genisteinGenisteinGenistein is one of several known isoflavones. Isoflavones, such as genistein and daidzein, are found in a number of plants including lupin, fava beans, soybeans, kudzu, and psoralea being the primary food source, also in the medicinal plant, Flemingia vestita and coffee Besides functioning as...
(from soy and other legumes)
Anthelmintic resistance
The ability of worms to survive treatments that are generally effective at the recommended dose rate is considered a major threat to the future control of worm parasites of small ruminants and horses.The clinical definition of resistance is a 95% or less reduction in a "Fecal Egg Count" test.
Treatment with an antihelminthic drug kills worms whose phenotype renders them susceptible to the drug.
Worms that are resistant survive and pass on their "resistance" genes.
Resistant worms accumulate and finally treatment failure occurs. See drug resistance
Drug resistance
Drug resistance is the reduction in effectiveness of a drug such as an antimicrobial or an antineoplastic in curing a disease or condition. When the drug is not intended to kill or inhibit a pathogen, then the term is equivalent to dosage failure or drug tolerance. More commonly, the term is used...
.