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.^a

Uses for Pyrantel

Enterobiasis

Treatment of enterobiasis caused by Enterobius vermicularis (pinworm infection).^{102 105 106 108 109} May be used for self-medication.^{100 103 108 109} Drugs of choice for enterobiasis are pyrantel, mebendazole, or albendazole.^{102 105}

Ascariasis

Has been used for treatment of ascariasis^{† [off-label]} caused by Ascaris lumbricoides.¹⁰⁶ Drugs of choice for ascariasis are albendazole, ivermectin, or mebendazole.^{102 105}

Intestinal Hookworm Infections

Treatment of intestinal hookworm infections caused by Ancylostoma duodenale^{† [off-label]} or Necator americanus^{† [off-label]}.^{102 105} Drugs of choice for intestinal hookworm infections are albendazole, mebendazole, or pyrantel.^{102 105}

Treatment of eosinophilic enterocolitis^{† [off-label]} caused by Ancylostoma caninum (dog hookworm).¹⁰² Drugs of choice are albendazole, mebendazole, or pyrantel.¹⁰² When indicated, endoscopic worm extraction also is considered a treatment of choice for eosinophilic enterocolitis.¹⁰²

Trichostrongyliasis

Treatment of trichostrongyliasis^{† [off-label]} caused by Trichostrongylus^†.¹⁰² Pyrantel is the drug of choice; albendazole and mebendazole are alternatives.¹⁰²

Oesophagostomiasis

May be effective for treatment of oesophagostomiasis^† caused by Oesophagostomum bifurcum.¹⁰² Albendazole is an alternative.¹⁰²

Moniliformis Infections

Treatment of infections caused by Moniliformis moniliformis^† (thorny-headed worm).¹⁰²

Pyrantel Dosage and Administration

Administration

Oral Administration

Administer orally.^{108 109} May be taken without regard to meals;^{108 109} may be taken or mixed with milk or fruit juice.^{102 108 109}

Shake oral suspension well before using.¹⁰⁸

Special diet, fasting, or purgation prior to administration not necessary.^{a 108 109}

Presence of pinworms should be confirmed visually before initiating self-medication.^{100 108 109}

Dosage

Available as pyrantel pamoate; dosage expressed in terms of pyrantel.^{108 109}

Pediatric Patients

Enterobiasis

Oral

11 mg/kg administered as a single dose; repeat dose after 2 weeks.¹⁰²

Self-medication in children ≥2 years of age: 11 mg/kg administered as a single dose.^{108 109} Do not repeat treatment unless directed by a clinician.^{100 108 109}

Treatment of all household contacts may be warranted when multiple or repeated symptomatic infections occur.^{102 105}

Intestinal Hookworm Infections†

Ancylostoma duodenale† or Necator americanus†

Oral

11 mg/kg once daily for 3 days.¹⁰²

Perform a repeat stool examination 2 weeks after treatment; repeat dosing regimen if results are positive.¹⁰⁵

Eosinophilic Enterocolitis Caused by Ancylostoma caninum† (Dog Hookworm)

Oral

11 mg/kg once daily for 3 days.¹⁰²

Trichostrongyliasis†

Oral

11 mg/kg administered as a single dose.¹⁰²

Moniliformis Infections†

Oral

11 mg/kg administered as a single dose; repeat dose twice at 2-week intervals for a total of 3 doses.¹⁰²

Adults

Enterobiasis

Oral

11 mg/kg administered as a single dose; repeat dose after 2 weeks.¹⁰²

Self-medication: 11 mg/kg administered as a single dose.^{108 109} Do not repeat treatment unless directed by a clinician.^{100 108 109}

Treatment of all household contacts may be warranted when multiple or repeated symptomatic infections occur.^{102 105}

Intestinal Hookworm Infections†

Ancylostoma duodenale† or Necator americanus†

Oral

11 mg/kg once daily for 3 days.¹⁰²

Perform a repeat stool examination 2 weeks after treatment; repeat dosing regimen if results are positive.¹⁰⁵

Eosinophilic Enterocolitis Caused by Ancylostoma caninum† (Dog Hookworm)

Oral

11 mg/kg once daily for 3 days.¹⁰²

Trichostrongyliasis†

Oral

11 mg/kg administered as a single dose.¹⁰²

Moniliformis Infections†

Oral

11 mg/kg administered as a single dose; repeat dose twice at 2-week intervals for a total of 3 doses.¹⁰²

Prescribing Limits

Pediatric Patients

Maximum single dose 1 g.¹⁰²

Adults

Maximum single dose 1 g.¹⁰²

Special Populations

No special population dosage recommendations at this time.^a

Cautions for Pyrantel

Contraindications

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

Warnings/Precautions

General Precautions

Patients with Severe Malnutrition or Anemia

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

Specific Populations

Pregnancy

Category C.¹⁰⁷

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

Pregnant women considering self-medication for treatment of enterobiasis should do so only under the direction of a clinician.^{100 108 109}

Pediatric Use

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

Hepatic Impairment

Use with caution in patients with preexisting liver dysfunction.¹⁰⁰

Individuals with liver disease considering self-medication for treatment of enterobiasis should do so only under direction of a clinician.^{108 109}

Common Adverse Effects

GI disturbances (nausea,^{108 109} vomiting,^{108 109} tenesmus,^a anorexia,^a diarrhea,^{108 109} abdominal cramps,^{108 109} gastralgia), headache,^{108 109} dizziness. ^{108 109}

Drug Interactions

Specific Drugs

Pyrantel Pharmacokinetics

Absorption

Bioavailability

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

Elimination

Metabolism

Partially metabolized in the liver.^a

Elimination Route

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

Stability

Storage

Oral

Suspension

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

Actions and Spectrum

• Pyrimidine-derivative anthelmintic agent.^a

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

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

Advice to Patients

• For self-medication of enterobiasis (pinworm infection), importance of providing patient a copy of manufacturer’s patient information.¹⁰⁰

• 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.^{108 109 a}

• Importance of informing clinician if symptoms of enterobiasis persist after treatment.¹⁰⁰ Importance of informing clinician if worms other than pinworms are present before or after therapy.^{100 108 109}

• Importance of informing clinician if abdominal disturbances (nausea, vomiting, diarrhea), headache, or dizziness persist or become bothersome after use of the drug.^{100 108 109}

• 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).^a

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

• 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

Frequently asked questions

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

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