Is Warfarin Really Rat Poison?
Tags: bleeding, blood thinner, rat poison, superwarfarins
Q: I’m on warfarin. Is it true that I’m taking RAT POISON?
YES, you’re taking a medicine that originally was used to kill rats. We know warfarin, by the brand names Coumadin® and Jantoven® and as its generic name, warfarin. Warfarin is part of a group of plant-based compounds called coumarins. Coumarins are found in red clover and sweet clover as well as many other plants. In the early 1920s, some veterinarians noticed that at certain times of the year some cows had problems with bleeding. They called this phenomenon “sweet clover disease” because it was eventually linked to cows that ate sweet clover hay which hadn’t been cured properly. Without proper drying, one of the compounds that naturally occurred in sweet clover was still active, and caused bleeding in the cows who ate the hay containing it. The compound responsible for the bleeding, dicumerol, was identified in 1934 and by the early 1940s it was being tested in humans as a blood-thinning agent, or anticoagulant.
In 1945, a more potent cousin of dicumerol was patented by the Wisconsin Alumni Research Foundation (WARF) and named after it, called warfarin. Warfarin was first used as a rat poison or rodenticide because it was considered to be too potent to be safely used in humans, but after a blood test was developed to measure and adjust its blood-thinning effects, warfarin has become the most widely used oral anticoagulant in the United States.
By the late 1940s a close relative of warfarin called coumafuryl was marketed as a rodenticide or rat poison under the brand names Rat-A-Way® and Lurat®. Rats resistant to these early coumarins triggered the development of more potent, second generation anticoagulants called “superwarfarins”, such as brodifacoum, difenacoum, bromadiolone and difethiolone. Brodifacoum is the rodenticide used by more than 50% of professional pest controllers in the United States.Today, 95% of rodent control in the United States is done with some form of anticoagulant.
I share my 18 years of experience helping people take their warfarin safely in my full-color handout How To Take Warfarin. It’s available as a FREE download here.