Ivermectin

What It Is

Ivermectin is a medication that belongs to a class of drugs known as antiparasitic agents. It was originally derived from avermectins—compounds discovered in the 1970s from a soil bacterium (Streptomyces avermitilis). It has since become a vital tool in global health, especially for treating and controlling parasitic infections.

In humans, ivermectin is approved by the U.S. Food and Drug Administration (FDA) for the treatment of several parasitic diseases, including:

• Onchocerciasis (river blindness) – caused by Onchocerca volvulus.
• Strongyloidiasis – an intestinal infection caused by Strongyloides stercoralis.
• It is also used off-label or as part of mass drug administration programs for other parasitic infections such as scabies and lice infestations.

How It Works

Ivermectin works by interfering with nerve and muscle function in parasites. Specifically, it binds to glutamate-gated chloride channels and enhances inhibitory neurotransmission. This causes:

1. Increased cell membrane permeability to chloride ions.
2. Hyperpolarization of nerve or muscle cells.
3. Paralysis and death of the parasite.

Importantly, ivermectin’s mechanism is highly selective for parasites. In humans, these specific chloride channels do not exist, and the drug does not readily cross the blood–brain barrier at therapeutic doses, which makes it relatively safe for human use when properly prescribed.

Why It’s Important

Ivermectin has had a profound impact on global public health, particularly in tropical and low-resource settings.

• Public health triumphs: It has been central to the near-eradication of river blindness in several regions of Africa and Latin America. Mass administration programs using ivermectin have dramatically reduced transmission rates of Onchocerca volvulus and Wuchereria bancrofti (which causes lymphatic filariasis).
• Accessibility: It is low-cost, widely available, and included on the World Health Organization’s (WHO) List of Essential Medicines.
• Broad-spectrum antiparasitic activity: Its efficacy against a range of ecto- and endoparasites makes it an indispensable drug in global health initiatives.

Although ivermectin gained attention during the COVID-19 pandemic for its purported antiviral effects, robust scientific studies and regulatory reviews have not found sufficient evidence to support its use for COVID-19 prevention or treatment outside of clinical trials.

Considerations

While ivermectin is generally safe when used as directed, several important considerations apply:

• Dosage and supervision: It should always be used under medical supervision. Overdosing can lead to serious side effects, such as confusion, low blood pressure, seizures, or liver injury.
• Drug interactions: It may interact with other medications that affect GABA (gamma-aminobutyric acid) transmission, potentially enhancing neurological effects.
• Vulnerable populations: Special care is needed for people with compromised blood–brain barriers (e.g., due to meningitis) or certain genetic conditions that affect drug metabolism (such as MDR1 gene mutations).
• Resistance concerns: In some regions, parasites have shown early signs of developing resistance, emphasizing the need for responsible use and monitoring.
• Off-label use: While it’s sometimes used for conditions like scabies, lice, or even experimental treatments, these should be guided by medical professionals and evidence-based guidelines.