What is the dosing regimen for mebendazole in patients of different ages and weights, including those with impaired liver or kidney function?

How to Administer Mebendazole

Mebendazole should be administered as 100 mg orally twice daily for 3 consecutive days for most helminthic infections in adults and children over 2 years of age. 1

Standard Dosing Regimen

Adults and Children ≥2 Years

• 100 mg orally twice daily for 3 consecutive days for treatment of nematode infections including ascariasis, trichuriasis, and hookworm 1, 2
• The tablets should be chewed 3
• This regimen achieves cure rates exceeding 85% for Ascaris lumbricoides, Trichuris trichiura, and hookworm infections 2

Alternative Single-Dose Regimens

• Single dose of 500-600 mg can be used for Trichuris infections, providing similar efficacy to the 3-day regimen with egg reduction rates over 80% 4
• Single-dose therapy is particularly useful for mass treatment programs due to ease of administration and better compliance 4
• The 300 mg single dose is less effective than the standard 3-day regimen and should be avoided 5

Special Populations

Infants and Young Children

• Mebendazole is contraindicated in infants <12 months of age 3
• For children 12-24 months, use the standard adult dose of 100 mg twice daily for 3 days 3

Pregnant Women

• Mebendazole should not be administered to pregnant women 3
• This is a critical contraindication that must be screened for before administration 3

Patients with Hepatic or Renal Impairment

• No dose adjustment is required for patients with liver or kidney dysfunction 1
• Only approximately 2% of administered mebendazole is excreted in urine, with the remainder excreted in feces as unchanged drug or metabolites 1
• Plasma levels remain extremely low (≤0.03 mcg/mL for parent drug) even with standard dosing, minimizing concerns about accumulation 1

Administration Considerations

Timing and Food

• Mebendazole can be taken with or without food 1
• For twice-daily dosing, administer approximately 12 hours apart 2

Concurrent Medications

• Vitamin A should be administered along with mebendazole in supplementary feeding programs, given every 3 months 3
• If diarrhea is present (common with heavy Trichuris infections), consider adding loperamide hydrochloride, which may enhance mebendazole efficacy 6

Clinical Pearls and Pitfalls

Common Pitfalls to Avoid

• Do not reduce the dose in children based on weight—the 100 mg twice daily dose is appropriate for all ages ≥12 months 3, 2
• Do not extend treatment beyond 3 days for routine nematode infections, as this does not improve efficacy 2
• Heavy Trichuris infections may show lower cure rates despite adequate dosing due to associated diarrhea reducing drug contact time 4

Safety Profile

• Mebendazole is extremely well-tolerated with no important side effects reported in clinical trials 2, 6
• The drug is devoid of adverse effects even with prolonged administration 7
• Risk of erratic Ascaris migration with single-dose therapy does not exceed that of multiple-dose regimens 4

Monitoring

• Post-treatment stool examination should be performed to confirm parasite eradication 2
• Expect >99% reduction in egg count per gram of stool for successful treatment 2
• If cure is not achieved after the first 3-day course, a repeat course can be administered with high success rates 6