Ivermectin
An avermectin antiparasitic taken by mouth for river blindness, strongyloidiasis and scabies, and used on the skin for head lice and rosacea.
Drug card
- Class
- Avermectin
- How it works
- Opening glutamate-gated chloride channels, paralyzing the parasite
- Used for
- River blindness (onchocerciasis)
- Strongyloidiasis of the gut
- Scabies
- Lymphatic filariasis, with albendazole
- Known for
- Mazzotti reaction: itch, rash, fever, swollen glands
- Encephalopathy in heavy Loa loa infection
- Its name
- -ectin means an avermectin antiparasitic (ivermectin type)
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does ivermectin work?
Ivermectin, a macrocyclic lactone from Streptomyces avermitilis, binds glutamate-gated chloride channels in invertebrate nerve and muscle, causing hyperpolarization, paralysis and death. It kills Onchocerca microfilariae but not adult worms, and acts only on the intestinal stages of Strongyloides. CYP3A4 metabolizes it, and a high-fat meal raises its absorption about 2.5-fold.
Uses
What is ivermectin used for?
- River blindness (onchocerciasis)
- Strongyloidiasis of the gut
- Scabies
- Lymphatic filariasis, with albendazole
- Head lice (as a lotion)
- Rosacea (as a cream)
Side effects
Side effects of ivermectin
- Mazzotti reaction: itch, rash, fever, swollen glandsKnown for
- Encephalopathy in heavy Loa loa infectionKnown forSerious
- Dizziness
- Nausea and diarrhea
- Drop in blood pressure on standing
- Fast heart rate
- Drowsiness, confusion, rarely comaSerious
- HepatitisSerious
- SJS and TENSerious
- SeizuresSerious
- Burning and irritation where cream is applied
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Test for loiasis before giving it to people from Loa loa areas of West or Central Africa: heavy infection risks encephalopathy.
- Oral ivermectin is not used in pregnancy or in children who weigh under 15 kg.
- It does not kill adult Onchocerca worms, so treatment is repeated, often yearly.
- It may raise the INR in people taking warfarin.
Good to know: WHO's core strategy against river blindness is mass treatment with donated ivermectin at least once a year, and WHO lists it as an essential medicine for scabies.
Remember it
A way to remember it
Ivermectin sounds like river: it is the drug for river blindness.
Ivermectin kills the microfilariae of Onchocerca volvulus, the worm behind river blindness (onchocerciasis), by opening their glutamate-gated chloride channels so their nerves and muscles are paralyzed.
Written for biofideX
Its name
-ectin means avermectin antiparasitic (ivermectin type)
Ivermectin and moxidectin share it. Ivermectin comes from Streptomyces avermitilis and opens glutamate-gated chloride channels in parasite nerves and muscle.
- Every drug name stem
Its class
Avermectins
Avermectins bind glutamate-gated chloride channels in the nerve and muscle cells of invertebrates such as worms, mites and lice, and open them. Chloride floods in, the cells hyperpolarize, and the parasite is paralyzed and dies. They are selective because they bind mammalian chloride channels only weakly and because ivermectin does not readily cross the human blood-brain barrier.
Easily mixed up with benzimidazole anthelmintics.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Ivermectin tablets: label (DailyMed)
- Ivermectin cream: label (DailyMed)
- Ivermectin lotion: label (DailyMed)
- Ivermectin (NCI Thesaurus)
- Onchocerciasis (WHO)
- Scabies (WHO)
- Lymphatic filariasis (WHO)
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Antifungals and antiparasitics
Ivermectin is one of 14 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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