What is the appropriate ivermectin dosing regimen (200 µg/kg oral dose repeated after one week) for scabies in adults and children ≥15 kg on chronic hemodialysis and for their close contacts?

Ivermectin Dosing for Scabies in Hemodialysis Patients and Contacts

Dosage Regimen

For adults and children ≥15 kg on chronic hemodialysis with scabies, administer ivermectin 200 µg/kg orally with food, repeated after 14 days, with no dose adjustment required for renal impairment. 1

• The standard dose is 200 µg/kg (for example, a 56-kg patient receives 12 mg total as four 3-mg tablets) given as a single dose on day 1, then repeated on day 15. 1
• No dosage adjustments are necessary for patients with renal impairment, including those on hemodialysis. 1, 2
• Ivermectin must be taken with food to increase bioavailability and enhance drug penetration into the epidermis. 1, 3, 2

Treatment Scheme Timeline

Day 1: First dose of ivermectin 200 µg/kg with food 1

Day 14-15: Second mandatory dose of ivermectin 200 µg/kg with food 1, 4

• The 2-week repeat dose is mandatory because ivermectin has limited ovicidal activity and does not kill all stages of the mite life cycle. 1, 4
• A second dose given 7-10 days after the first substantially improves cure rates. 4

Contact Management

All household members, close contacts, and sexual partners within the previous month must be treated simultaneously with the same regimen, even if asymptomatic. 1, 3, 2

• Contacts should receive ivermectin 200 µg/kg on day 1 and day 14-15, identical to the index patient. 1
• Failure to treat asymptomatic contacts simultaneously is a frequent cause of reinfection and treatment failure. 3
• This simultaneous treatment prevents the cycle of reinfection between the patient and their contacts. 3, 2

Pediatric Considerations for Contacts

Children weighing <15 kg or under 10 years old should NOT receive ivermectin due to potential neurotoxicity from blood-brain barrier penetration. 1, 3, 2

• For pediatric contacts <15 kg, use permethrin 5% cream instead, applied from neck down (or entire body including scalp if <2 years), left on 8-14 hours, then washed off. 3
• Recent research suggests ivermectin may be safe in children 2-4 years weighing 10-14 kg at a 3 mg dose, but this remains off-label and guidelines still recommend permethrin for this age group. 5, 6

Post-Treatment Expectations

Pruritus and rash may persist for up to 2 weeks after successful treatment due to allergic dermatitis, not treatment failure. 1, 3, 2

• Topical corticosteroids and oral antihistamines can relieve persistent itching during this period. 1
• Retreatment should only be considered after 2 weeks if live mites are observed or symptoms persist beyond 2 weeks. 3, 2
• Premature retreatment within the first 2 weeks based solely on persistent itching should be avoided. 3

Environmental Decontamination

Machine-wash and dry all bedding, clothing, and towels using hot cycles, or isolate items from skin contact for at least 72 hours. 3, 2

• Scabies mites cannot survive off the human host for longer than 72 hours. 3
• Fumigation of living areas is not required for scabies eradication. 3, 2

Critical Pitfalls to Avoid

Forgetting the second dose on day 14-15 is the most common error, as single-dose therapy has substantially lower cure rates. 1, 4

Not treating all contacts simultaneously leads to reinfection cycles and apparent treatment failure. 1, 3

Taking ivermectin without food markedly reduces absorption and treatment efficacy. 1, 3

Using ivermectin in children <15 kg or <10 years risks neurotoxicity; permethrin is the appropriate alternative for this population. 1, 3, 2