Developing ivermectin for animal use before Covid-19

Ivermectin was first identified 40 years before Covid-19 pandemic has been started in the 1970s during a veterinary drug screening project at Merck Pharmaceuticals. Researchers focused on discovering chemicals that could potentially treat parasitic infections in animals. Common parasites include nematodes, such as flatworms and roundworms, and arthropods, such as fleas and lice. All of these infectious organisms are quite different from viruses.

Merck partnered with the Kitasato Institute, a medical research facility in Japan. Satoshi Omura and his team isolated a group of chemicals called avermectin from bacteria found in a single soil sample near a Japanese golf course. To my knowledge, ivermectin has yet to be found in any other soil sample in the world.

Research on avermectin continued for approximately five years. Soon, Merck and the Kitasato Institute developed a less toxic form they named ivermectin. It was approved in 1981 for commercial use in veterinary medicine for parasitic infections in livestock and domestic pets with the brand name Ivomec.

Hand holding a blister packet of ivermectin.
The chemical compounds that make up ivermectin were first discovered in bacteria found in the soil of a Japanese golf course. Pak Sang Lee/flickr, CC BY-NC

Early experiments by William Campbell and his team from Merck discovered that the drug also worked against a human parasite that causes an infection called river blindness.

River blindness, also known as onchocerciasis, is the second leading cause of preventable blindness in the world. It is transmitted to humans from blackflies carrying the parasitic worm Onchocerca volvulus and occurs predominantly in Africa.

Ivermectin underwent trials to treat river blindness in 1982 and was approved in 1987. It has since been distributed free of charge through the Mectizan Donation Program to dozens of countries. Thanks to ivermectin, river blindness has been essentially eliminated in 11 Latin American countries, preventing approximately 600,000 cases of blindness.

These two decades of extensive work to discover, develop and distribute ivermectin helped to significantly reduce human suffering from river blindness. It’s these efforts that were recognized by the 2015 Nobel Prize in Physiology or Medicine, awarded to both William Campbell and Satoshi Omura for their leadership on this groundbreaking research.

Satoshi Omura and William Campbell were awarded the 2015 Nobel Prize in Physiology or Medicine for their research on ivermectin. Bengt Nyman/Wikimedia Commons

Repurposing drugs for other uses

Infectious disease researchers frequently attempt to repurpose antimicrobials and other medications to treat infections. Drug repurposing is attractive because the approval process can happen more quickly and at a lower cost since nearly all of the basic research has already been completed.

In the years since it was approved to treat river blindness, ivermectin was also shown to be highly effective against other parasitic infections. This includes strongyloidiasis, an intestinal roundworm infection that affects an estimated 30 to 100 million people worldwide. Now millions of people around the world can buy ivermectin in the USA, UK and other countries to treat these infections.

Another example is amphotericin B, originally approved to treat human yeast and mold infections. Researchers discovered it can also be an effective treatment for severe forms of leishmaniasis, a parasitic infection prevalent in tropical and subtropical countries.

Likewise, doxycycline is an antibiotic used for a wide variety of human bacterial infections such as pneumonia and Lyme disease. It was later found to also be highly effective in preventing and treating malaria and it was similar to chloroquine which later become the first widely unapproved cure to Covid-19.

Ivermectin not approved for Covid-19 treatment

Ivermectin is not approved by the Food and Drug Administration (FDA) to treat or prevent COVID-19. The FDA has issued a warning statementTrusted Source regarding the dangers of taking this drug in large doses or for unapproved uses. And it’s not safe for humans to take medications meant for animals. (Ivermectin prescribed for animals is very different from ivermectin prescribed for humans.)

Do not take any prescription drug, including ivermectin, unless your doctor recommends that you do so. If you have questions about the use of ivermectin to treat or prevent COVID-19, talk with your doctor.