Ivermectin Dosage for Scabies in an 86kg Adult
For an 86kg adult with scabies, the recommended dose is 6 tablets of ivermectin 3mg (total 18mg), taken as a single oral dose, with a second identical dose repeated after 2 weeks. 1, 2
Dosage Calculation
- The CDC/MMWR guidelines recommend ivermectin at 200μg/kg (0.2mg/kg) for scabies 1
- For an 86kg individual: 86kg × 0.2mg/kg = 17.2mg
- With 3mg tablets: 17.2mg ÷ 3mg = 5.73 tablets
- Therefore, 6 tablets (18mg) is the appropriate dose
Administration Instructions
- Take all 6 tablets at once as a single dose
- Take with food to increase bioavailability and enhance penetration into the epidermis 1
- A second identical dose (6 tablets) should be administered 14 days after the first dose 1
Rationale for Two-Dose Regimen
- Ivermectin has limited ovicidal activity and may not prevent recurrences from eggs present at the time of treatment 1
- The second dose eliminates newly hatched mites that survived the first treatment
- Studies show higher cure rates with two doses compared to a single dose 3, 4
Additional Management Considerations
- Decontaminate bedding and clothing (machine wash and dry using hot cycle) or remove from body contact for at least 72 hours 1
- Keep fingernails closely trimmed to reduce injury from excessive scratching 1
- Treat all household members and close contacts simultaneously to prevent reinfestation 1
- Be aware that pruritus may persist for up to 2 weeks after effective treatment 1
Important Considerations
- Higher dosing (400μg/kg) has been studied and may be more effective with a single dose 3, but the standard recommended dose is 200μg/kg 1, 2
- Eczematous eruptions have been reported as a potential adverse effect within 72 hours of administration 3
- Ivermectin should be taken with food because bioavailability is increased 1
- No dosage adjustment is required for patients with renal impairment 1
This dosage regimen provides optimal efficacy while maintaining safety for the treatment of scabies in an adult weighing 86kg.