Ivermectin Is a Game-Changing Nobel Prize-Winning Wonder Drug – But Not for COVID-19

By Jeffrey R. Aeschlimann, University of Connecticut October 21, 2021

Although ivermectin was originally used to treat river blindness, it has also been reused to treat other parasitic infections in humans.

Ivermectin is a more than 30-year-old wonder drug that treats life- and face-threatening parasitic infections. Its lasting impact on global health has been so profound that two of the foremost researchers in its discovery and development won the Nobel Prize in 2015.

I have been an infectious disease pharmacist for over 25 years. I have also mentored patients who have delayed appropriate treatment for their severe COVID-19 infections because they believed ivermectin could cure them.

While ivermectin has been a game-changer for people with certain infectious diseases, it won’t save patients from COVID-19 infection. It could even cost them their lives.

Let me tell you a short story about the history of ivermectin.

Ivermectin is commonly used to treat and control parasites in animals, including horses.

Developing ivermectin for use in animals

Ivermectin was first identified 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 these infectious organisms are very 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, avermectin has not yet been found in any other soil sample in the world.

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

The chemical compounds that make up ivermectin were first discovered in bacteria found in the bottom of a Japanese golf course. Credit: Pak Sang Lee

Development of ivermectin for human use

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

River blindness, also called onchocerciasis, is the second leading cause of preventable blindness in the world. It is transmitted to humans by black flies carrying the parasitic worm Onchocerca volvulus and is mainly found in Africa.

Ivermectin underwent trials in 1982 to treat river blindness and was approved in 1987. Since then, it has been distributed for free through the Mectizan donation program in dozens of countries. Thanks to ivermectin, river blindness has essentially been 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 have contributed to significantly reducing human suffering from river blindness. It is 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 in this groundbreaking research.

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

Reusing medicines for other uses

Infectious disease researchers often try to reuse antimicrobials and other drugs to treat infections. Drug repurposing is attractive because the approval process can be faster and at a lower cost, as almost all basic research has already been completed.

In the years since it was approved for the treatment of river blindness, ivermectin has also been 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.

Another example is amphotericin B, originally approved to treat human yeast and fungal infections. Researchers found that it may also be an effective treatment for severe forms of leishmaniasis, a parasitic infection common in tropical and subtropical countries.

Similarly, doxycycline is an antibiotic used for a wide variety of human bacterial infections such as pneumonia and Lyme disease. It was later found to be very effective in preventing and treating malaria as well.

Ivermectin has been used to treat strongyloidiasis, an intestinal infection that can be life-threatening for immunocompromised people.

Reusing drugs for COVID-19

However, not every attempt to repurpose a drug works as hoped.

At the start of the pandemic, scientists and doctors were trying to find low-cost drugs to treat and prevent COVID-19. Chloroquine and hydroxychloroquine were two of those drugs. They were chosen because of potential antiviral effects documented in lab studies and limited anecdotal case reports of the first COVID-19 outbreaks in China. However, large clinical trials of these drugs for the treatment of COVID-19 have not translated into meaningful benefits. This was partly due to the severe toxic effects patients experienced before the drugs reached a high enough dose to inhibit or kill the virus.

Unfortunately, lessons from these failed attempts have not been applied to ivermectin. The false hopes surrounding the use of ivermectin to treat COVID-19 arose from an April 2020 lab study in Australia. Although the results of this research were widely disseminated, I immediately had serious doubts. The concentration of ivermectin they tested was 20 to 2,000 times higher than the standard doses used to treat human parasitic infections. Many other pharmaceutical experts confirmed my initial concerns within a month of the article’s publication. Such high concentrations of the drug can be significantly toxic.

Another oft-cited article on ivermectin’s alleged effects against COVID-19 was retracted in July 2021 after scientists found serious flaws in the study. These shortcomings ranged from inaccurate statistical analyzes to discrepancies between collected data and published results to duplicate patient records and the inclusion of subjects who died before even participating in the study. Even more worryingly, at least two other oft-cited studies have raised significant concerns about scientific fraud.

At the time of writing, two large randomized clinical trials both showed no significant benefit from using ivermectin for COVID-19. Reputable national and international health organizations, including the World Health Organization, the Centers for Disease Control and Prevention, the National Institutes of Health, the Food and Drug Administration, and the Infectious Diseases Society of America, unanimously advise against the use of ivermectin to or treat COVID-19 , except as part of a clinical trial.

Consequences of using ivermectin for COVID-19

Unfortunately, many organizations with questionable intentions have continued to promote unfounded use of invermectin for COVID-19. This has led to a dramatic rise in prescriptions for ivermectin and a deluge of calls to US poison centers for ivermectin overdoses. Many calls were due to the ingestion of large amounts of veterinary products containing ivermectin – two deaths were reported in September 2021 associated with an ivermectin overdose.

Ivermectin, when used correctly, has prevented millions of potentially deadly and debilitating infectious diseases. It is only intended to be prescribed for the treatment of infections caused by parasites. It is not intended to be prescribed by parasites seeking to make money from desperate people during a pandemic. It is my sincere hope that this unfortunate and tragic chapter in the otherwise incredible story of a life-saving drug will soon come to an end.

Written by Jeffrey R. Aeschlimann, associate professor of pharmacy, University of Connecticut.

This article was first published in The Conversation.