How is a Horse Like a Human?

They are both mammals, they share some identical genes, but they should not share the same drug: ivermectin.

What is ivermectin? Ivermectin is an avermectin – a type of naturally occurring drug, by way of fermentation – discovered through culture of the fungus Streptomyces avermitilis in 1967. It is an effective anti-parasitic drug whose discoverers won the Nobel Prize in 2015.

Ivermectin has been and is currently used to treat humans and animals for pathogen infestation or infection, and is part of the World Health Organization’s (WHO’s) Model List of Essential Medicines. Ivermectin may stop diseases like onchocerciasis or river blindness, an illness caused by helminths that damage capillaries of the eye; lymphatic filariasis, with accumulation of Wucheria worms in lymph vessels or glands; and scabies, a skin irritation caused by Sarcoptes mites. It may be administered by tablet, ointment, or injection in appropriate concentrations. 

In our crazy COVID-19 times, its use against viral infection has been tested in humans, and the drug is currently being utilized to treat COVID-positive patients in 24 developing countries, including India, Peru, and others.

“But SARS-CoV-2 is a virus, not a parasite, correct?” one might ask. “Why would one think a drug which affects growth of parasites could also inhibit growth of viruses?”

Viruses and parasites are different types of microbes. Viruses are considered non-living, as they require a host to reproduce. Parasites are classified in the same grouping as humans: eukaryotes. They may function alone, but thrive on nutrients and housing from a host. Both viruses and parasites may elicit a similar outcome from infection in the human body, namely clumping of blood cells, or microvascular occlusion.

The commonality of disease sequelae prompted investigators to question if ivermectin might prove useful for treatment of COVID-19 patients. The alteration in blood clotting may damage the lining, or endothelium, of capillaries. When damaged vessels surround the alveoli or functional units for gas exchange in lungs, victims are deprived of oxygen, hence the need for ventilators in severe COVID-19 cases.

As of July 2021, the National Institutes of Health (NIH) followed 16 of 55 studies for assessment of ivermectin’s effects on COVID-19 cases. It is thought that ivermectin interferes with one or more of 20 identified levels for infection, level one being binding virus to host cells (blocked by steric hindrance?), through host inflammatory responses, thus stopping viral progression.

Some studies have been discounted for small sample size, non-randomization of subjects, or incomplete follow-up. Dr. Omura, the ivermectin Nobel co-laureate, with colleagues, published a review with data showing a sizable decrease in morbidity and mortality for human COVID-19 patients treated with ivermectin.

Due to fervent wishes to stay safe, people have taken drugs intended for animal use. The Food and Drug Administration (FDA) recently tweeted, “you are not a horse. You are not a cow. C’mon ya’ll. Stop it.” The formulations and dosages for animal medications are NOT appropriate for humans. The ivermectin injection for cattle contains polyethylene glycol (PEG), a.k.a. antifreeze.

Ivermectin holds promise for SARS treatment: it has been approved, is inexpensive, and could be repurposed. But the best primary prevention for COVID-19 remains the Pfizer, Moderna, or J&J vaccine!

Programming Note: Listen to Julia Brodt report this story live today during Talk Ten Tuesdays, 10 Eastern.