Description

Ivermectin is an antiparasitic drug belonging to the class of avermectins. It is a semisynthetic macrocyclic lactone derived from the soil microorganism Streptomyces avermitilis. Ivermectin is a broad-spectrum antiparasitic agent that is highly effective against a wide range of parasites, particularly nematodes (roundworms) and arthropods. It is available in various oral and topical formulations.

Indication

Ivermectin is indicated for the treatment of several parasitic infections. Its main uses include:

• Strongyloidiasis: It is a first-line treatment for strongyloidiasis, an intestinal infection caused by the parasitic roundworm Strongyloides stercoralis.

• Onchocerciasis (River Blindness): It is a cornerstone of global public health programs for the control of onchocerciasis, an eye and skin disease caused by the parasite Onchocerca volvulus.

• Scabies: It is used as an oral treatment for human scabies, an infestation caused by the mite Sarcoptes scabiei.

• Other Parasitic Infections: It is also used to treat infections caused by other parasites, such as cutaneous larva migrans and pediculosis (head lice).

Mechanism of Action

Ivermectin’s mechanism of action is highly specific to the nervous system of invertebrates, which accounts for its efficacy and relatively low toxicity in mammals.

1. Binding to Glutamate-Gated Chloride Channels: Ivermectin works by binding with high affinity to glutamate-gated chloride (Cl−) ion channels. These channels are found exclusively in the nerve and muscle cells of invertebrates, but are not present in mammals.

2. Increased Chloride Permeability: When ivermectin binds to these channels, it causes a significant increase in the permeability of the cell membrane to chloride ions. This influx of negative chloride ions into the cell leads to a process called hyperpolarization.
3. Paralysis and Death: The hyperpolarization of the nerve and muscle cells makes them unable to be stimulated. This results in the tonic paralysis of the parasite’s pharyngeal and somatic muscles, which prevents the parasite from feeding and moving. This sustained paralysis leads to the death of the parasite.
4. Selective Toxicity: The selective toxicity of ivermectin is due to two key factors:
   • Mammalian nerve cells do not have glutamate-gated chloride channels.
   • Ivermectin does not readily cross the blood-brain barrier in mammals, further reducing its potential for neurological side effects in the host.