Pyrantel pamoate

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Pyrantel pamoate
Pyrantel pamoate.png
IUPAC name
4-[(3-Carboxy-2-hydroxynaphthalen-1-yl)methyl]-3-hydroxynaphthalene-2-carboxylic acid; 1-methyl-2-[(E)-2-thiophen-2-ylethenyl]-5,6-dihydro-4H-pyrimidine
22204-24-6 N
ChEMBL ChEMBL1599768 N
ChemSpider 4444501 YesY
Jmol 3D model Interactive image
MeSH Pyrantel+pamoate
PubChem 5281033
Molar mass 594.6768 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Pyrantel pamoate (under US Pharmacopoeia) 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 and pamoic acid. Some drug companies pair pyrantel pamoate with praziquantel for tapeworms, and sometimes febantel for whipworms in order to provide more complete treatment for intestinal parasites in one dose.

It is also used for pinworm treatment. There are a number of brands, including "Reese's Pinworm Medicine", "Pin-X", "Pin-Rid","PYRANTRIN" formally called "COMBANTRIN", "Anthel", "Helmintox", "Helmex" and Drontal Cat.

Pyrantel pamoate is also commonly included in monthly administered chewable heartworm preventative tablets for dogs.


Pyrantel pamoate is considered a Pregnancy category 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. [1]

Drug action[edit]

Pyrantel pamoate acts as a depolarizing neuromuscular blocking agent, thereby causing sudden contraction, followed by paralysis, of the helminths. 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.[2] 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.

See also[edit]


  1. ^ Plumb, D. C. (2005). Plumb's veterinary drug handbook. Stockholm, Wis: PharmaVet. ISBN 0-8138-0518-X. 
  2. ^ Salman, A. B. (1997). "Management of intestinal obstruction caused by ascariasis". Journal of Pediatric Surgery. 32 (4): 585–587. doi:10.1016/S0022-3468(97)90712-0. PMID 9126759.