Mebendazole

Pronunciation: meh-BEND-uh-zole
Class: Benzimidazole

Trade Names

Vermox
- Tablets, chewable 100 mg

Pharmacology

Kills parasitic worms by blocking glucose uptake, thus depleting stored glycogen. Without glycogen, parasite cannot reproduce or survive.

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Pharmacokinetics

Absorption

Mebendazole is poorly absorbed (approximately 5% to 10%). T _max is 0.5 to 7 h and C _max is 0.03 mcg/mL. Food increases the absorption of mebendazole.

Distribution

Mebendazole is distributed to serum, cyst fluids, liver, omental fat, pelvic cysts, pulmonary cysts, hepatic cysts, and muscles. Mebendazole also crosses the placenta. Protein binding is 90% to 95%.

Metabolism

All metabolites are inactive. The major metabolite is 2-amino-5-benzoylbenzimidazole. Mebendazole is primarily metabolized hepatically.

Elimination

Mebandazole is excreted in the feces and a small amount in urine. The t _½ is 2.5 to 9 h.

Special Populations

The t _½ is prolonged to approximately 30 h.

Indications and Usage

Treatment of pinworm ( Enterobius vermicularis ), round worm ( Ascaris lumbricoides ), common hookworm ( Ancylostoma duodenale ), American hookworm ( Necator americanus ), and whipworm ( Trichuris trichiura ) in single or mixed parasitic infections.

Contraindications

Standard considerations.

Dosage and Administration

PO 100 mg tablet AM and PM on 3 consecutive days.

PO 500 mg as single dose.

PO 100 mg as single dose.

Storage/Stability

Store in tightly closed container at room temperature.

Drug Interactions

Pharmacological effects of mebendazole may be decreased.

Laboratory Test Interactions

None well documented.

Adverse Reactions

GI

Transient abdominal pain and diarrhea.

Miscellaneous

Fever.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Safety and efficacy in children younger than 2 yr of age not established.

Overdosage

Symptoms

GI complaints.

Patient Information

• Advise patient to chew tablet or to crush tablet and mix with food.
• Instruct patient to wash clothing, bed linens, and towels daily and to disinfect bathroom facilities daily.
• Advise that infected person sleep alone.
• Caution patient not to put fingers in mouth.
• Emphasize importance of thorough hand washing, especially after toileting, to avoid reinfecting self.
• Explain that all family members should be treated to eradicate infestation.
• Tell patient that second treatment is sometimes necessary.
• Instruct family/patient to call health care provider if fever, abdominal pain, or diarrhea develops.

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