Pyrantel is a medication used to treat a number of

parasitic worm infection Helminthiasis, also known as worm infection, is any macroparasitic disease of humans and other animals in which a part of the body is infected with parasitic worms, known as helminths. There are numerous species of these parasites, which are br ...

s. This includes

ascariasis Ascariasis is a disease caused by the parasitic roundworm ''Ascaris lumbricoides''. Infections have no symptoms in more than 85% of cases, especially if the number of worms is small. Symptoms increase with the number of worms present and may in ...

hookworm infection Hookworm infection is an infection by a type of intestinal parasite known as a hookworm. Initially, itching and a rash may occur at the site of infection. Those only affected by a few worms may show no symptoms. Those infected by many worms may ...

enterobiasis Pinworm infection (threadworm infection in the UK), also known as enterobiasis, is a human parasitic disease caused by the pinworm. The most common symptom is itching in the anal area. The period of time from swallowing eggs to the appearance ...

(pinworm infection),

trichostrongyliasis ''Trichostrongylus'' species are nematodes (round worms), which are ubiquitous among herbivores worldwide, including cattle, sheep, donkeys, goats, deer, and rabbits.Garcia LS, editor. Diagnostic Medical Parasitology. 5 ed. Washington, DC: ASM P ...

, and

trichinellosis Trichinosis, also known as trichinellosis, is a parasitic disease caused by roundworms of the ''Trichinella'' type. During the initial infection, invasion of the intestines can result in diarrhea, abdominal pain, and vomiting. Migration of lar ...

. It is taken by mouth. Side effects include nausea, headache, dizziness, trouble sleeping, and rash. A lower dose should be used in people with liver disease. While it does not appear to be harmful during

pregnancy Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ca ...

, it has not been studied for this use. It is unclear if it is safe for use during

breastfeeding Breastfeeding, or nursing, is the process by which human breast milk is fed to a child. Breast milk may be from the breast, or may be expressed by hand or pumped and fed to the infant. The World Health Organization (WHO) recommends that br ...

. It is in the

antihelmintic 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 ...

family of medications. It works by paralyzing worms. Pyrantel was initially described in 1965. It is on the

World Health Organization's List of Essential Medicines The WHO Model List of Essential Medicines (aka Essential Medicines List or EML), published by the World Health Organization (WHO), contains the medications considered to be most effective and safe to meet the most important needs in a health ...

. Pyrantel is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

. It may also be used to treat worms in a number of other animals.

Pregnancy and breastfeeding

Pyrantel pamoate is considered a

pregnancy category The pregnancy category of a medication is an assessment of the risk of fetal injury due to the pharmaceutical, if it is used as directed by the mother during pregnancy. It does ''not'' include any risks conferred by pharmaceutical agents or their ...

C drug for use during pregnancy for humans, but is in category A for canines and felines. Pyrantel is considered safe to use in nursing animals.

Mechanism of action

Pyrantel pamoate acts as a

depolarizing neuromuscular blocking agent Neuromuscular-blocking drugs block neuromuscular transmission at the neuromuscular junction, causing paralysis of the affected skeletal muscles. This is accomplished via their action on the post-synaptic acetylcholine (Nm) receptors. In c ...

, thereby causing sudden contraction, followed by paralysis, of the

helminths Parasitic worms, also known as helminths, are large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other parasitic worms such as schi ...

. This has the result of causing the worm to "lose its grip" on the intestinal wall and be passed out of the system by natural process. Since Pyrantel is poorly absorbed by the host's intestine, the host is unaffected by the small dosage of medication used. Spastic (tetanic) paralyzing agents, in particular pyrantel pamoate, may induce complete intestinal obstruction in a heavy worm load. This obstruction is usually in the form of a worm impaction and happens when a very small, but heavily parasitized animal is treated and tries to pass a large number of dislodged worms at once. Worms usually pass in normal stool or with diarrhea, straining, and occasional vomiting.

Names

There are a number of brands, including "Reese's Pinworm Medicine", "Pin-X", "Pin-Rid","PYRANTRIN", "COMBANTRIN", "Anthel", "Helmintox", "Helmex", "Strongid" and Drontal Cat.

References

External links

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