Pyrantel pamoate or Pyrantel Embonate (under European Pharmacopoeia), is used as a deworming agent in the treatment of hookworms (all species) and roundworms (Ascaris lumbricoides, aka ascarids in humans) in domesticated animals such as horses, cattle, sheep, pigs, cats, dogs, and many other species. It is a combination of pyrantel

Pyrantel

Pyrantel is an antinematodal thiophene. It is often prescribed by veterinarians to treat and prevent the occurrence of intestinal parasites in small animal pets.-Mechanism of Action:Pyrantel is a nicotinic receptor agonist...

 and pamoic acid

Pamoic acid

Pamoic acid, also called embonic acid, is a naphthoic acid derivative. Salts and esters of pamoic acid are known as pamoates or embonates. It can be prepared by the reaction of 2-hydroxy-3-naphthoic acid with formaldehyde...

. Some drug companies pair pyrantel pamoate with praziquantel

Praziquantel

Praziquantel 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....

 for tapeworms, and sometimes febantel for whipworm

Whipworm

The human tapworm is a roundworm, which causes trichuriasis when it infects a human large intestine. The name whipworm refers to the shape of the worm; they look like whips with wider "handles" at the posterior end.-Life cycle:The female T. trichiura produces 2,000–10,000 single celled eggs per day...

s in order to provide more complete treatment for intestinal parasites in one dose.

It is also used for pinworm treatment for humans in many brands, including "Reese's Pinworm Medicine", "Pin-X", "Pin-Rid", "Combantrin", "Anthel", "Helmintox", "Helmex".

Pyrantel pamoate is also commonly included in monthly administered chewable heartworm

Heartworm

Heartworm is a parasitic roundworm that is spread from host to host through the bites of mosquitoes. The heartworm is a type of filaria, a small thread-like worm. The definitive host is the dog but it can also infect cats, wolves, coyotes, foxes and other animals, such as ferrets, sea lions and...

 tablets for cats and dogs.

Drug action

Pyrantel pamoate acts as a depolarizing neuromuscular blocking agent, thereby causing sudden contraction, followed by paralysis, of the helminths

Parasitic worm

Parasitic worms or helminths are a division of eukaryoticparasites that, unlike external parasites such as lice and fleas, live inside their host. They are worm-like organisms that live and feed off living hosts, receiving nourishment and protection while disrupting their hosts' nutrient...

. 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. Dosage is 11 mg/kg not to exceed 1 g as a single dose.

Toxicity

Pyrantel pamoate is considered a Pregnancy category

Pregnancy category

The pregnancy category of a pharmaceutical agent 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 metabolites that are present in breast...

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.