mebendazole
Vermox

Available forms
Available by prescription only
Tablets (chewable): 100 mg

Indications and dosages
 Pinworm infestations. Adults and children older than age 2: 100 mg P.O. as a single dose. If infection persists 2 weeks later, repeat treatment.
 Other roundworm, whipworm, and hookworm infestations ◇; trichostrongylosis ◇. Adults and children older than age 2: 100 mg P.O. b.i.d. for 3 days. If infection persists 3 weeks later, repeat treatment. Or, for treatment of hookworm, whipworm, or roundworm, 500 mg P.O. as a single dose.
 Trichinosis ◇. Adults: 200 to 400 mg P.O. t.i.d. for 3 days; then 400 to 500 mg t.i.d. for 10 days.
 Capillariasis ◇. Adults: 200 mg P.O. b.i.d. for 20 days.
 Toxocariasis ◇. Adults and children: 200 to 400 mg P.O. daily divided into two doses for 5 days.
 Dracunculiasis ◇. Adults: 400 to 800 mg P.O. daily for 6 days.
 Mansonella perstans infestations ◇. Adults: 100 mg P.O. b.i.d. for 30 days.
 Angiostrongylus cantonensis infestations ◇. Adults and children: 100 mg P.O. b.i.d. for 5 days.
 Onchocerciasis ◇. Adults: 1 g P.O. b.i.d. for 28 days.
 Treatment of hydatid disease (echinococcosis) ◇. Adults: 40 mg/kg P.O. for 1 to 6 months. Or, sequential 2-week courses of 50 mg/kg daily, 200 mg/kg daily, and 50 mg/kg daily for 21 to 30 days.
 Angiostrongylus costaricensis ◇. Adults and children: 600 to 1,200 mg P.O. daily divided t.i.d. for 10 days.

Pharmacodynamics
Anthelmintic action: Mebendazole inhibits uptake of glucose and other low-molecular-weight nutrients in susceptible helminths, depleting the glycogen stores they need for survival and reproduction. It has a broad spectrum and may be useful in mixed infections. It’s considered a drug of choice in the treatment of ascariasis, capillariasis, enterobiasis, trichuriasis, and uncinariasis; it has been used investigationally to treat echinococciasis, onchocerciasis, and trichinosis.

Pharmacokinetics
Absorption: About 5% to 10% is absorbed. Absorption varies widely among patients.
Distribution: Highly bound to plasma proteins; it crosses the placental barrier.
Metabolism: Metabolized to inactive 2-amino-5(6)-benzimidazolyl phenylketone.
Excretion: Most of a dose is excreted in feces; 2% to 10% is excreted in urine in 48 hours as either unchanged drug or the 2-amine metabolite. Half-life is 3 to 9 hours. It isn’t known if drug appears in breast milk.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug.

Interactions
Drug-drug. Anticonvulsants, including carbamazepine and phenytoin: May enhance mebendazole metabolism and decrease its efficacy. Monitor patient for clinical effect.
Cimetidine: Inhibits mebendazole metabolism and may increase its plasma level. Use together cautiously.

Adverse reactions
CNS: fever.
GI: occasional, transient abdominal pain and diarrhea in massive infection and expulsion of worms.

Effects on lab test results
None reported.

Overdose and treatment
Signs and symptoms of overdose may include GI disturbances and altered mental status.
 No specific recommendations exist; treatment is supportive. After recent ingestion (within 4 hours), empty stomach by induced emesis or gastric lavage. Follow with activated charcoal to decrease absorption.

Special considerations
• Tablets may be chewed, swallowed whole, or crushed and mixed with food.
• Laxatives, enemas, or dietary restrictions are not needed.
• Collect stool specimens in a clean, dry container and transfer to a properly labeled container to send to laboratory; ova may be destroyed by toilet bowl water, urine, and some drugs.
• High-dose treatment of hydatid disease and trichinosis is investigational. Frequently monitor WBC count to detect drug toxicity, especially during initial therapy.
• Store drug at 59° to 77° F (15° to 25° C) in well-closed container; product expires 3 years from date of manufacture.
Breast-feeding patients
• Safety in breast-feeding women hasn’t been established.
Pediatric patients
• Give drug to children younger than age 2 only when potential benefits justify risks.

Patient education
• Teach patient and family members personal hygiene measures to prevent reinfection, including washing perianal area and changing undergarments and bedclothes daily; washing hands and cleaning fingernails before meals and after defecation; and sanitary disposal of feces.
• Advise patient to bathe often, by showering, if possible.
• Advise patient to keep hands away from mouth, to keep fingernails short, and to wear shoes to avoid hookworm. Explain that ova are easily transmitted directly and indirectly by hands, food, or contaminated articles. Washing clothes in household washing machine will destroy ova.
• Instruct patient to handle bedding carefully because shaking will send ova into the air, and to disinfect toilet facilities and vacuum or damp-mop floors daily to reduce number of ova.
• Encourage patient’s family and contacts to be checked for infestation and treated, if necessary.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use