What is the proper use and dosage of Ivermectin for treating parasitic infections?

Ivermectin Dosage and Administration for Parasitic Infections

For treating parasitic infections, oral ivermectin should be administered at a dose of 200 μg/kg (micrograms per kilogram) body weight, taken with food to increase bioavailability, with a second dose administered 14 days after the first dose to ensure complete eradication. 1, 2

Standard Dosing for Common Parasitic Infections

Strongyloidiasis

• Single oral dose of 200 μg/kg body weight 2
• Take tablets with food to increase bioavailability and drug penetration into the epidermis 1
• Follow-up stool examinations should be performed to verify eradication 2

Scabies (Regular)

• 200 μg/kg orally, repeated in 2 weeks 1
• Second dose is necessary because ivermectin has limited ovicidal activity and may not prevent recurrences from eggs present at the time of treatment 1
• Not recommended for children weighing less than 15 kg 1

Crusted Scabies (Norwegian Scabies)

• More aggressive dosing regimen required due to higher parasite burden 1
• Combination treatment recommended with:
  • Oral ivermectin 200 μg/kg on days 1,2,8,9, and 15 1
  • Additional doses on days 22 and 29 may be required for severe cases 1
  • Plus topical scabicide (5% permethrin cream or 5% benzyl benzoate) applied daily for 7 days then twice weekly until cure 1

Pediculosis Pubis (Pubic Lice)

• 250 μg/kg repeated in 2 weeks 1
• Alternative to first-line topical treatments when they fail 1

Special Populations and Considerations

Pregnancy

• Ivermectin is classified as "human data suggest low risk" in pregnancy 1
• Likely compatible with breastfeeding 1

Children

• Safety not established in children weighing less than 15 kg 1
• For head lice in children, ivermectin should not be used for children weighing less than 15 kg due to risk of crossing blood-brain barrier 1

Renal Impairment

• No dosage adjustments required in patients with renal impairment 1

Hepatic Impairment

• Safety of multiple doses in patients with severe liver disease is not known 1
• Use with caution in patients with severe hepatic disease 1

Administration Guidelines

• Take with food to increase bioavailability 1
• For strongyloidiasis: See weight-based dosing table 2:
  • 15-24 kg: 1 tablet (3 mg)
  • 25-35 kg: 2 tablets
  • 36-50 kg: 3 tablets
  • 51-65 kg: 4 tablets
  • 66-79 kg: 5 tablets
  • ≥80 kg: Calculate 200 μg/kg

Treatment Efficacy and Safety

• Ivermectin is effective against various parasites including strongyloidiasis, scabies, and some protozoal infections 3, 4
• For strongyloidiasis, a 2-day regimen (200 μg/kg daily for 2 consecutive days) has shown 100% cure rate compared to 77% with single-day treatment 5
• Common side effects include:
  • Mild and short-duration effects such as edema, rash, headache 6
  • Pruritus may persist for up to 2 weeks after treatment due to allergic reaction to dead parasites 1

Important Precautions

• Exclude Loa loa infection in people who have traveled to endemic regions BEFORE treating with ivermectin 1
• Ivermectin is a substrate for P-glycoprotein; genetic polymorphisms or co-administration of P-glycoprotein inhibitors may increase neurotoxicity risk 6
• Bedding and clothing should be decontaminated (machine-washed and dried using hot cycle) or removed from body contact for at least 72 hours 1
• Retreatment after 2 weeks should be considered for patients who remain symptomatic or when live parasites are still observed 1