What is the recommended dosing regimen for ivermectin (antiparasitic medication) for deworming in an adult patient with a parasitic infection, considering weight, potential liver or kidney disease, and pregnancy status?

Ivermectin Dosing for Deworming

For deworming in adults with parasitic infections, administer ivermectin 200 mcg/kg (0.2 mg/kg) orally as a single dose, repeated in 2 weeks, taken on an empty stomach with water. 1, 2

Standard Dosing Regimen

• The universal dose is 200 mcg/kg body weight (approximately 12 mg for a 60 kg adult, or 6 mg for a 30 kg patient) 1
• Must be taken on an empty stomach with water to optimize bioavailability 2
• Repeat the same dose 14 days after the first dose because ivermectin has limited ovicidal activity and may not prevent recurrence from eggs present at initial treatment 3

Indication-Specific Variations

Hookworm and Soil-Transmitted Helminths

• Ivermectin 200 mcg/kg combined with albendazole 400 mg as single doses for empiric treatment of suspected geohelminth infections 1
• This combination is recommended for travelers from endemic areas with clinical suspicion but negative diagnostic testing 1

Strongyloidiasis

• Standard: 200 mcg/kg single dose 2
• Immunocompromised patients require extended dosing: 200 mcg/kg on days 1,2,15, and 16 2

Scabies

• 200 mcg/kg orally, repeated in 2 weeks 3, 2
• Permethrin 5% cream is preferred as it is more effective, safer, and less expensive than ivermectin 3

Special Population Considerations

Renal Impairment

• No dose adjustments required for patients with kidney disease 3, 2

Hepatic Impairment

• Safety of multiple doses in severe liver disease is not established 3, 2
• Use caution and consider alternative agents in patients with advanced cirrhosis

Pregnancy and Lactation

• Ivermectin is classified as "human data suggest low risk" in pregnancy and is probably compatible with breastfeeding 3, 2
• No teratogenicity or toxicity has been observed in human pregnancy experience 3

Pediatric Patients

• Children under 10 years should not receive ivermectin for scabies; use permethrin cream instead 2
• For children 12-24 months with suspected hookworm, expert consultation is recommended before treatment 1

Critical Safety Warnings

Elderly and Debilitated Patients

• One study demonstrated increased mortality among elderly, debilitated persons who received ivermectin, though this has not been confirmed in subsequent reports 3, 2
• Exercise heightened caution in frail elderly patients

Co-infection Screening

• Always exclude Loa loa infection before treating with ivermectin in anyone who has traveled to endemic regions 2
• Risk of severe adverse events including encephalitis in hypermicrofilaremic patients (>8,000 mf/mL) with loiasis 2
• Exclude co-existing onchocerciasis before treating loiasis, and exclude loiasis before treating lymphatic filariasis or onchocerciasis 2

Administration Tips

• Take with food to increase bioavailability and enhance penetration into the epidermis 3
• Note: This contradicts the CDC recommendation to take on empty stomach 2; the guideline for scabies specifically recommends taking with food for better tissue penetration 3

Common Pitfalls to Avoid

• Do not give single dose only: The second dose at 2 weeks is essential due to limited ovicidal activity 3
• Do not use in children under 10 years for scabies: Permethrin is the appropriate choice 2
• Do not skip screening for Loa loa in travelers from endemic areas: This can result in life-threatening complications 2
• Do not assume cure without follow-up: Consider repeating stool examination 2-3 weeks after treatment if symptoms persist 1