Pharm

Ivermectin

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Ivermectin, Mectizan, Stromectol

  • Indication
  1. Scabies (refractory to Permethrin 5%)
  2. Head Lice
  3. Strongyloidiasis
  4. Onchocerciasis
  • Mechanism
  1. Developed initially as veterinary anti-parasitic agent
  2. Related to Macrolide antibiotics
  3. Also decreases Nerve Impulse transmission
    1. Potentiates GABA-gated chloride channels
  • Pharmacokinetics
  1. Peak Level: 3-6 hours after intake
  2. Half-Life: >12 hours
  3. Metabolized by Cyp 3A4
  4. Crosses blood brain barrier via P-Glycoprotein (ABCB1 Transporter)
  • Preparations
  1. Ivermectin 6 mg tablet
  • Dosing
  1. Scabies or Head Lice
    1. Ivermectin 200 mcg/kg PO x1 dose, repeat in 10 days
  2. Strongyloidiasis
    1. Ivermectin 200 mcg/kg PO for 1 dose
  3. Onchocerciasis
    1. Ivermectin 150 mcg/kg PO for 1 dose
  1. Studies show efficacy over Lindane for Scabies
    1. Madan (2001) J Dermatol 28:481-4 [PubMed]
  2. Permethrin 5% appears to be more effective for Scabies
    1. Usha (2000) J Am Acad Dermatol 42:236-40 [PubMed]
  • Precautions
  1. Safe in children >15 kg (33 pounds)
  2. Avoid in Lactation
  3. Pregnancy Category: C
  • Adverse Effects
  • Reaction - Allergy to Parasite Death
  1. Nausea
  2. Fever
  3. Headache
  4. Arthralgia
  5. Rash
  1. Doses <500 mg in adults and <5mg/kg in children are typically without reaction
  2. In 2021, patients were taking very high doses for COVID-19 (based on little evidence of benefit)
    1. High dose toxicity (Seizures, coma, death) was at risk at these doses (e.g. 600 mg taken for several days)
    2. Patients ingested high risk formulations (topical Ivermectin, veterinary Ivermectin)
  3. Findings typically resolve within 6-8 hours of ingestion
  4. Gastrointestinal Findings
    1. Nausea or Vomiting
    2. Abdominal Pain
    3. Diarrhea
  5. Neurologic Findings
    1. Headache
    2. Dizziness
    3. Hallucinations
    4. Confusion
  6. Cardiopulmonary Findings
    1. Hypotension
    2. Tachycardia
  7. Skin Findings
    1. Urticaria
    2. Edema
  8. Management
    1. See Unknown Ingestion
    2. Activated Charcoal
      1. Indicated in early presentation of large ingestion
    3. Supportive Management
      1. ABC Management
      2. Benzodiazepines for Seizures
      3. Consider Intravenous Lipid Emulsion
  • Reference
  1. Tomaszewski (2021) Crit Dec Emerg Med 35(9): 32
  2. Meinking (1995) N Engl J Med 333:26 [PubMed]
  3. Fawcett (2003) Am Fam Physician 68(6):1089-92 [PubMed]