Pyrantel is an anthelmintic first developed for use in veterinary practice. It is effective against various intestinal helminths in both animals and humans, and very little toxicity has been associated with its use. Pyrantel is marketed as the pamoate salt and is used in the treatment of infections caused by roundworm, hookworm, and pinworm. Pyrantel was FDA-approved in 1971 and is available without a prescription.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Oral Administration
-Pyrantel is administered orally.
-May administer with food, milk or fruit juice, at any time of day.
-Fasting, purgation, or special diets are not necessary for effective treatment.
Oral Liquid Formulations
-Shake well before use.
-Liquid products can be mixed with milk or fruit juice. Measure liquid products with a calibrated oral dosing device to administer an accurate dosage.
The most common GI disorders during therapy with pyrantel include nausea, vomiting, diarrhea, and abdominal pain or cramps.
Dizziness and headache may occur with the use of pyrantel.
Pyrantel should be used with caution in patients with hepatic disease.
Pyrantel chewable tablets contain phenylalanine; use with caution in patients with phenylketonuria.
Pyrantel is poorly absorbed from the GI tract. There are no well controlled studies of pyrantel use in pregnant women. Use pyrantel with caution during pregnancy. Some experts suggest that single-dose pyrantel therapy may be given to pregnant women. Pregnant women should not take pyrantel unless directed by a doctor.
There are no data regarding the presence of pyrantel in breast milk. Pyrantel is poorly absorbed from the GI tract; therefore, excretion into breast milk may be minimal. Some experts suggest single-dose pyrantel therapy may be given to breast-feeding women. Breast-feeding infant exposure may be minimized if the drug is taken just before the longest sleep interval for the infant.
Doses are described as pyrantel base. 1 mg of pyrantel base is equivalent to 2.88 mg of pyrantel pamoate salt.
Per the manufacturer, this drug has been shown to be active against most strains of the following microorganisms either in vitro and/or in clinical infections: Ascaris lumbricoides, Enterobius vermicularis
NOTE: The safety and effectiveness in treating clinical infections due to organisms with in vitro data only have not been established in adequate and well-controlled clinical trials.
For the treatment of ascariasis (roundworm infection)*:
Oral dosage:
Adults: 11 mg/kg base/dose (Max: 1 g/dose) PO once daily for 3 days as an alternative.
Children and Adolescents: 11 mg/kg base/dose (Max: 1 g/dose) PO once daily for 3 days as an alternative.
For the treatment of enterobiasis (pinworm infection):
Oral dosage:
Adults: 11 mg/kg base/dose (Max: 1 g/dose) PO as a single dose; repeat dose in 2 weeks.
Children and Adolescents 2 to 17 years weighing 11 kg or more: 11 mg/kg base/dose (Max: 1 g/dose) PO as a single dose; repeat dose in 2 weeks.
Children 2 to 12 years weighing less than 11 kg*: 11 mg/kg base/dose PO as a single dose; repeat dose in 2 weeks. Consult physician and do not self-treat.
Children 1 year*: 11 mg/kg base/dose PO as a single dose; repeat dose in 2 weeks. Consult physician and do not self-treat.
For the treatment of hookworm infection*:
Oral dosage:
Adults: 11 mg/kg base/dose (Max: 1 g/dose) PO once daily for 3 days.
Children and Adolescents: 11 mg/kg base/dose (Max: 1 g/dose) PO once daily for 3 days.
For the treatment of trichostrongyliasis*:
Oral dosage:
Adults: 11 mg/kg base (Max: 1 g) PO as a single dose.
Infants, Children, and Adolescents: 11 mg/kg base (Max: 1 g) PO as a single dose.
Maximum Dosage Limits:
-Adults
11 mg/kg/dose PO, not to exceed 1 g/dose PO.
-Geriatric
11 mg/kg/dose PO, not to exceed 1 g/dose PO.
-Adolescents
11 mg/kg/dose PO, not to exceed 1 g/dose PO.
-Children
2 years and older: 11 mg/kg/dose PO, not to exceed 1 g/dose PO.
1 year: 11 mg/kg/dose PO has been used off-label.
-Infants
11 mg/kg/dose PO has been used off-label.
-Neonates
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Self-treatment is not recommended.
Patients with Renal Impairment Dosing
Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.
*non-FDA-approved indication
There are no drug interactions associated with Pyrantel products.
By stimulating the release of acetylcholine, inhibiting cholinesterase, and stimulating ganglionic neurons, pyrantel acts as a depolarizing neuromuscular blocking agent in helminths. These actions cause extensive depolarization of the helminth muscle membrane, producing tension of the helminth's muscles, which causes paralysis and release of their hold to the intestinal wall. This action is unlike piperazine, which is a hyperpolarizing neuromuscular blocking agent that relaxes helminth muscles, causing a subsequent detachment from the intestinal wall. Expulsion of the parasites from the GI tract occurs by normal peristalsis.
Pyrantel is administered orally. The absorbed drug is partially metabolized in the liver, with approximately 7% or less of the dose being excreted in urine as unaltered drug and metabolites and more than 50% of each dose being excreted unchanged in the feces.
Affected cytochrome P450 isoenzymes and drug transporters: none
-Route-Specific Pharmacokinetics
Oral Route
Pyrantel has poor and incomplete absorption from the GI tract. Peak plasma concentrations (0.05 to 0.13 mcg/mL) occur within 1 to 3 hours.