How Animal Research Helped Bring Ivermectin to the World

The Science Behind Ivermectin and the Role of Animal Models

Animal models played a crucial role in the discovery, development and safety testing of ivermectin, a lifesaving antiparasitic drug. It’s also a success story of public-private partnership. Here’s a breakdown of how different animals contributed.

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Step-by-Step Research Journey

How Animal Models Shaped Ivermectin’s Success

Explore each phase of ivermectin development—from initial discovery and preclinical studies with livestock and dogs, through primate testing, to human use and Nobel recognition—highlighting the critical role of animal research in safe and effective drug development.

Discovery Phase

Mice and rats were part of early screening for antiparasitic activity.
The original compound, avermectin, was discovered from Streptomyces avermitilis, a soil bacterium isolated by Dr. Satoshi Ōmura at the Kitasato Institute’s Antibiotics Research Group in Tokyo, Japan. Merck & Co. Inc. scientist Dr. William C. Campbell tested the compound with rodent models for antiparasitic effects. Streptomyces avermitilis was isolated by Ōmura, and its extracts were sent to the pharmaceutical company, where Campbell and colleagues conducted further testing.

Efficacy Testing With Livestock

Cattle, sheep, pigs and horses were early targets for ivermectin use, since it was initially developed as a veterinary medicine.
These animals were in trials to confirm ivermectin’s ability to eliminate internal and external parasites, such as gastrointestinal worms, mites and lice.

Canine Studies

Dogs were tested to demonstrate ivermectin’s effectiveness against heartworm disease.
Safety studies with dogs also identified potential neurotoxic effects in certain breeds with a genetic mutation (MDR1), helping to define safe dosage limits.

Nonhuman Primates (NHPs)

Nonhuman primates were essential in preclinical development to model how ivermectin might behave in the human body.
These studies helped establish how the drug works in the body and the proper dosage, paving the way for human clinical trials.

Transition to Human Use

Following successful veterinary use and extensive testing with animal models, ivermectin was adapted for human use in the 1980s. Ivermectin was approved for human use in 1987, following Merck’s collaboration with the World Health Organization.
It became a groundbreaking treatment for onchocerciasis (river blindness) and lymphatic filariasis (also known as elephantiasis), ultimately saving millions of lives in endemic regions.

Nobel Prize

In 2015, Drs. Satoshi Ōmura and William C. Campbell won the Nobel Prize in Physiology or Medicine for the discovery of avermectin and its development into the antiparasitic drug ivermectin — a breakthrough made possible through extensive research with animal models.

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