The Full Story
You might not have heard of it before, but pyrantel is a drug used to treat a serious condition suffered by millions of people every year. That condition is intestinal worms. The worms (helminths) cause symptoms ranging from abdominal pain and loss of appetite to dysentery. Drugs used to combat intestinal worms are known as anthelmintics.
Intestinal worms are transmitted through soil that is contaminated with feces containing the eggs of worms. When a person or animal ingests soil (from unwashed hands or food), the eggs hatch in the intestines and lead to illness. Worms can also be transmitted to humans by handling pets, such as dogs and cats that have not been treated for worms. Pet birds can also carry worms. Since intestinal worms can be transmitted from animals to people, they are considered "zoonotic" infestations.
According to the World Health Organization, soil-transmitted worm infestations afflict close to 1 billion people worldwide. About 10% of the population in the developing world is affected. In heavily infested areas, more than 50% of people can have intestinal worms. People in developing regions are at higher risk due to poor sanitation. Worm infestations can follow contact with household pets and other animals such as horses, cattle, sheep, goats, pigs, and llamas. Dogs and cats entering animal shelters are routinely treated for worms using pyrantel or other anthelmintic medications. Since an estimated 68% of households in the US own at least one pet, control of intestinal worms in pets has become an essential safeguard in preventing transmission to humans. In addition, children can pick up worm infestations by playing in dirt contaminated with feces and not washing their hands before eating or putting their hands in their mouths. If a person is diagnosed with intestinal worms, the entire household should be treated to prevent spread and reinfestation.
Pyrantel is a safe, effective, and inexpensive treatment for several types of intestinal worms. It has been in use since the mid-1970s. The most common form of pyrantel for human and veterinary use is pyrantel pamoate. The drug is FDA-approved for pinworm infestations. It is also effective for roundworms, hookworms, and whipworms. It is available without a prescription as a generic medication or under brand names such as Antiminth, Reese's Pinworm Medicine, Ascarel, and Pin-X. Pyrantel for veterinary use is found in products like Heartgard Plus, Strongid-T, and Nemex. Pyrantel cures worm infestations by paralyzing the worms, which then release from the intestines and travel out of the body in the stool.
Pyrantel has the advantage of being usually effective after a single oral dose. In some cases, a second dose might be needed 2 weeks later. Another good thing about pyrantel is that it is not well absorbed into the body from the intestines, so it produces very few side effects. At most, mild symptoms such as nausea, diarrhea, headache, and dizziness might be expected. In very rare cases, pyrantel has caused temporary worsening of myasthenia gravis (resulting in muscle weakness) due to the drug's effect on nerve receptors controlling muscular movements. It is important to note that people of Asian descent are at higher risk for this type of reaction to pyrantel (see "This Really Happened"). Even with an overdose of pyrantel, no toxicity is expected. In fact, there are no reports of serious human poisoning with pyrantel in the medical literature.
If you have questions about an adverse reaction or possible overdose of pyrantel, immediately check the webPOISONCONTROL®
online tool or call Poison Control at 1-800-222-1222 for help 24 hours a day, every day.
Leslie A. McCament-Mann, PhD, RPh
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