Pyrantel (Monograph)

Brand names: Ascarel, Pin-X, Reese’s Pinworm Medicine
Drug class: Anthelmintics
VA class: AP200
CAS number: 22204-24-6

Introduction

Anthelmintic; pyrimidine-derivative.

Uses for Pyrantel

Enterobiasis

Treatment of enterobiasis caused by Enterobius vermicularis (pinworm infection). May be used for self-medication. Drugs of choice for enterobiasis are pyrantel, mebendazole, or albendazole.

Ascariasis

Has been used for treatment of ascariasis^{† [off-label]} caused by Ascaris lumbricoides. Drugs of choice for ascariasis are albendazole, ivermectin, or mebendazole.

Intestinal Hookworm Infections

Treatment of intestinal hookworm infections caused by Ancylostoma duodenale^{† [off-label]} or Necator americanus^{† [off-label]}. Drugs of choice for intestinal hookworm infections are albendazole, mebendazole, or pyrantel.

Treatment of eosinophilic enterocolitis^{† [off-label]} caused by Ancylostoma caninum (dog hookworm). Drugs of choice are albendazole, mebendazole, or pyrantel. When indicated, endoscopic worm extraction also is considered a treatment of choice for eosinophilic enterocolitis.

Trichostrongyliasis

Treatment of trichostrongyliasis^{† [off-label]} caused by Trichostrongylus^†. Pyrantel is the drug of choice; albendazole and mebendazole are alternatives.

Oesophagostomiasis

May be effective for treatment of oesophagostomiasis^† caused by Oesophagostomum bifurcum. Albendazole is an alternative.

Moniliformis Infections

Treatment of infections caused by Moniliformis moniliformis^† (thorny-headed worm).

Pyrantel Dosage and Administration

Administration

Oral Administration

Administer orally. May be taken without regard to meals; may be taken or mixed with milk or fruit juice.

Shake oral suspension well before using.

Special diet, fasting, or purgation prior to administration not necessary.

Presence of pinworms should be confirmed visually before initiating self-medication.

Dosage

Available as pyrantel pamoate; dosage expressed in terms of pyrantel.

Pediatric Patients

Enterobiasis

Oral

11 mg/kg administered as a single dose; repeat dose after 2 weeks.

Self-medication in children ≥2 years of age: 11 mg/kg administered as a single dose. Do not repeat treatment unless directed by a clinician.

Treatment of all household contacts may be warranted when multiple or repeated symptomatic infections occur.

Intestinal Hookworm Infections†

Ancylostoma duodenale† or Necator americanus†

Oral

11 mg/kg once daily for 3 days.

Perform a repeat stool examination 2 weeks after treatment; repeat dosing regimen if results are positive.

Eosinophilic Enterocolitis Caused by Ancylostoma caninum† (Dog Hookworm)

Oral

11 mg/kg once daily for 3 days.

Trichostrongyliasis†

Oral

11 mg/kg administered as a single dose.

Moniliformis Infections†

Oral

11 mg/kg administered as a single dose; repeat dose twice at 2-week intervals for a total of 3 doses.

Adults

Enterobiasis

Oral

11 mg/kg administered as a single dose; repeat dose after 2 weeks.

Self-medication: 11 mg/kg administered as a single dose. Do not repeat treatment unless directed by a clinician.

Treatment of all household contacts may be warranted when multiple or repeated symptomatic infections occur.

Intestinal Hookworm Infections†

Ancylostoma duodenale† or Necator americanus†

Oral

11 mg/kg once daily for 3 days.

Perform a repeat stool examination 2 weeks after treatment; repeat dosing regimen if results are positive.

Eosinophilic Enterocolitis Caused by Ancylostoma caninum† (Dog Hookworm)

Oral

11 mg/kg once daily for 3 days.

Trichostrongyliasis†

Oral

11 mg/kg administered as a single dose.

Moniliformis Infections†

Oral

11 mg/kg administered as a single dose; repeat dose twice at 2-week intervals for a total of 3 doses.

Prescribing Limits

Pediatric Patients

Maximum single dose 1 g.

Adults

Maximum single dose 1 g.

Special Populations

No special population dosage recommendations at this time.

Cautions for Pyrantel

Contraindications

• Known hypersensitivity to pyrantel or any ingredient in the formulation.

Warnings/Precautions

General Precautions

Patients with Severe Malnutrition or Anemia

Use caution in patients with severe malnutrition or anemia. Ideally, anemic, dehydrated, or malnourished patients should receive supportive therapy prior to administration of pyrantel.

Specific Populations

Pregnancy

Category C.

Use during pregnancy only if benefits justify risks to the fetus and only when no alternative management is appropriate.

Pregnant women considering self-medication for treatment of enterobiasis should do so only under the direction of a clinician.

Pediatric Use

Safety and efficacy not established in children <2 years of age; use in this age group only when potential benefits justify possible risks.

Hepatic Impairment

Use with caution in patients with preexisting liver dysfunction.

Individuals with liver disease considering self-medication for treatment of enterobiasis should do so only under direction of a clinician.

Common Adverse Effects

GI disturbances (nausea, vomiting, tenesmus, anorexia, diarrhea, abdominal cramps, gastralgia), headache, dizziness.

Drug Interactions

Specific Drugs

Pyrantel Pharmacokinetics

Absorption

Bioavailability

Poorly absorbed from GI tract. Peak serum concentrations occur 1–3 hours after a dose.

Elimination

Metabolism

Partially metabolized in the liver.

Elimination Route

Approximately 50% of an oral dose is excreted unchanged in feces; 7% excreted in urine as unchanged drug and metabolites.

Stability

Storage

Oral

Suspension

<30°C, tight, light-resistant container.

Actions and Spectrum

• Pyrimidine-derivative anthelmintic agent.

• Depolarizing neuromuscular blocking agent. Paralyzes worms which are then expelled from the GI tract by peristalsis.

• Active against Enterobius vermicularis (pinworm), Ascaris lumbricoides (roundworm), Ancylostoma duodenale (hookworm), Necator americanus (hookworm), and Trichostrongylus orientalis (hairworm).

Advice to Patients

• For self-medication of enterobiasis (pinworm infection), importance of providing patient a copy of manufacturer’s patient information.

• When using to treat enterobiasis, importance of treating all household members and importance of taking hygienic precautions to minimize reinfection, including wearing tight underpants both day and night, cleaning the bedroom floor by vacuuming or damp mopping for several days after treatment, washing and not shaking bed linens and night clothes after treatment, and keeping toilet seats clean.

• Importance of informing clinician if symptoms of enterobiasis persist after treatment. Importance of informing clinician if worms other than pinworms are present before or after therapy.

• Importance of informing clinician if abdominal disturbances (nausea, vomiting, diarrhea), headache, or dizziness persist or become bothersome after use of the drug.

• Importance of informing clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses (e.g., anemia, hepatic disease).

• Importance of women informing their clinician if they are or plan to become pregnant or plan to breast-feed.

• Importance of informing patients of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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Frequently asked questions

• Pyrantel - what is the dosage for cats and kittens?

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