Action And Clinical Pharmacology: Pyrantel exerts its anthelmintic effect by interfering with the neuromuscular function of the parasite. It is also a cholinesterase inhibitor and a ganglionic stimulant.
The anthelmintic activity of pyrantel has been demonstrated in several animal models. These tests carried out in mice and dogs showed the compound to be effective against intestinal nematodes representative of those found in humans, such as pinworms, large roundworms and hookworms. It is poorly absorbed by the intestinal mucosa so that its activity is confined to the lumen of the bowel. In the dog, the peak plasma levels were low and similarly the tissue levels were low. Less than 15% is excreted via the urine, the major proportion of the dose being excreted in the feces.
Indications And Clinical Uses: For the treatment of infection with any of the following gastrointestinal parasites when these are present either alone or as a mixed infection. Enterobius vermicularis (threadworm, pinworm) Ascaris lumbricoides (roundworm), Ancylostoma duodenale (hookworm), Necator americanus (hookworm), Trichostrongylus colubriformis and T. orientalis.
Pyrantel should be used for the treatment of infection with one or more of these parasites in both adults and children. It is well tolerated and will not stain the oral mucosa upon ingestion or the clothing by fecal contamination. The presence of an infection with any of the 5 parasites in one member of a family or group of persons in close proximity may indicate unidentified infection in other members. In these circumstances, pyrantel administration to all the family or group members is recommended. (Rigorous cleaning of living quarters and clothing to destroy helminthic ova will help prevent reinfection.)
Contra-Indications: In patients who are hypersensitive to the drug or to any of the components of the product.
Manufacturers’ Warnings In Clinical States: Pregnancy: Animal reproductive studies have not resulted in any teratogenic effects, but pyrantel has not been studied in the pregnant patient. It should not be used in pregnant women, unless in the judgment of the physician it is deemed essential for the welfare of the patient.
Lactation: It is not known whether pyrantel is excreted in breast milk; nursing should be discontinued if use of this drug is deemed essential.
Children: Pyrantel should not be used in children under the age of 1 year because safety in this age group has not been established.
Precautions: Should be used with caution in patients with pre-existing hepatic dysfunction, as minor transient elevations of AST have occurred in a small percentage of patients.
Occupational Hazards: The effect of pyrantel on the ability to drive and operate heavy machinery has not been studied. There is no evidence to suggest that pyrantel pamoate may affect these abilities.
Adverse Reactions: Pyrantel is well tolerated. The infrequent side effects consist for the most part of vomiting and diarrhea. Headache, insomnia, irritability, drowsiness, dizziness, anorexia, abdominal cramps, nausea and rash have seldom been reported. While adverse reactions have been few at the recommended, therapeutic dose of 11 mg/kg, they become considerably more frequent at higher dose concentrations without significant gain in therapeutic effect. No significant changes in total blood count, urinalysis, AST, ALT, alkaline phosphatase and BUN have been observed.
Symptoms And Treatment Of Overdose: Symptoms: Because of its low rate of absorption, plasma concentrations are low. The probable effects of overdosage would include autonomic dysfunction, muscle spasm, twitches and weakness, prostration and ultimately asphyxia due to muscular paralysis.
Treatment: No specific antidote is known. Early gastric lavage and measures to support respiration and blood pressure may be advisable.
Dosage And Administration: Pyrantel should be administered in a single oral dose determined on the basis of body weight, i.e., 11 mg/kg. Treatment of pinworm and roundworm: See Table I.
Treatment of Hookworm: The same dosage as in Table I given once daily for 3 days.
Pyrantel may be administered without regard to ingestion of food or time of day, and purging is not necessary prior to or during therapy. On rare occasions a second dose has been necessary to eradicate pinworm or roundworm infection. Pyrantel may be taken with milk or fruit juice. The presence of an infection of Enterobius in one patient may indicate unidentified infections in other members of the family. Pyrantel pamoate treatment for all family members is recommended. Rigorous cleaning of living quarters and clothing to destroy helmintic ova and strict attention to personal hygiene will help prevent reinfection. It will not stain the oral mucosa upon ingestion or the clothing by fecal contamination.
Children: Use in infants under 1 year is not recommended because safety in this age group has not been established.
Availability And Storage: Suspension: Each mL of caramel-flavored suspension contains: pyrantel pamoate equivalent to 50 mg of pyrantel base. Nonmedicinal ingredients: antifoam, citric acid, imitation caramel flavor, glycerin, lecithin, polysorbate 80, povidone, sodium benzoate, sorbitol, veegum and water. Tartrazine-free. Amber glass bottles of 50 mL. The suspension must be kept in the amber glass container to protect from light.
Tablets: Each round, pale orange, scored tablet, contains: pyrantel pamoate equivalent to 125 mg of pyrantel base. Nonmedicinal ingredients: alginic acid, cornstarch, FD&C Yellow #6, magnesium stearate, sodium lauryl sulfate and water. Tartrazine-free. Amber plastic blister packages of 12. Tablets must be kept in the amber blister package to protect from light.
Store between 15 and 30°C.
COMBANTRIN® Pfizer Consumer Pyrantel Pamoate Anthelmintic