What are the uses of Ivermectin?

Ivermectin Uses

Ivermectin is FDA-approved only for the treatment of strongyloidiasis (intestinal threadworm) and onchocerciasis (river blindness), with no proven efficacy for COVID-19 or other viral infections despite its in vitro activity. 1

FDA-Approved Indications

Strongyloidiasis

• FDA recommends a single oral dose of 200 mcg/kg for intestinal strongyloidiasis 1
• Efficacy is measured by absence of larvae in follow-up stool examinations 2
• Significantly more effective than albendazole, with cure rates of 83-92% compared to 38-55% 1, 3
• Follow-up recommendation: At least three stool examinations over three months following treatment to ensure eradication, as recrudescence can occur up to 106 days post-treatment 2
• Concentration techniques (using Baermann apparatus) should be employed for stool examinations 2

Onchocerciasis (River Blindness)

• FDA recommends a single oral dose of 150 mcg/kg given annually 1
• Causes dramatic reduction in skin microfilariae counts 2
• Clinical studies show 83.2% decrease in skin microfilariae count 3 days after dosing and 99.5% decrease after 3 months 2
• Marked reduction >90% maintained for up to 12 months after a single dose 2

Other Established Uses (Off-Label)

Lymphatic Filariasis

• Effective against microfilariae of Wuchereria bancrofti and Brugia malayi 1
• Used in mass treatment programs for lymphatic filariasis, though not officially FDA-approved for this indication 1

Ectoparasitic Infections

• Particularly effective for crusted (Norwegian) scabies and head lice 1
• Strong clinical evidence supports its use in these conditions 1, 4

Pharmacology and Mechanism of Action

• Binds selectively to glutamate-gated chloride ion channels in invertebrate nerve and muscle cells 1, 2
• Increases cell membrane permeability to chloride ions, resulting in hyperpolarization, paralysis, and death of parasites 1, 2
• Metabolized in the liver primarily by CYP3A4 1, 2
• Plasma half-life approximately 18 hours following oral administration 2
• Excreted almost exclusively in feces over approximately 12 days 2
• Bioavailability increases 2.5-fold when taken with high-fat meals 2

Important Cautions and Contraindications

• Not recommended for COVID-19 treatment or prevention 1

  • Multiple randomized controlled trials show no beneficial effect on mortality, need for mechanical ventilation, hospitalization rates, or viral clearance 1
  • The concentrations required to inhibit SARS-CoV-2 in vitro are considerably higher than those achievable in human plasma and lung tissue 1, 5

• Common adverse effects include:

  • Edema, rash, headache, and ocular complaints 1, 5
  • Risk of severe systemic postural hypotension 1
  • Severe encephalopathy when treating patients with high microfilarial loads 1

• Drug interactions:

  • May interact with P-glycoprotein inhibitors to increase neurotoxicity 1, 5
  • Genetic polymorphisms in P-glycoprotein may increase risk of neurotoxicity 5

Clinical Pearls

• Follow-up is critical for strongyloidiasis treatment to ensure eradication 2
• When treating onchocerciasis, be aware of potential increase in microfilariae count in the anterior chamber of the eye at day 3 after treatment 2
• Ivermectin does not readily cross the blood-brain barrier in humans, contributing to its safety profile 2
• The use of ivermectin for off-label indications, except for specific parasitic conditions mentioned above, is not supported due to insufficient evidence 1