Friday, April 28, 2017

Poisoning People for Fun and Profit #27—Warfarin




Did you know that warfarin, also known as Coumadin—that stuff that Grampa takes to prevent a stroke—was originally developed as a rat poison? It came as a surprise to me.


Kale can combat the effects of Warfarin
In high doses it can kill a human. It's a touchy drug, that doesn't get on well with lots of food. Especially green leafy foods like broccoli and kale and parsley, which diminish its effects. (Any food that's high in Vitamin K will interfere with it.)

It becomes more potent when taken with aspirin or other NSAID drugs like Advil and it's also given a boost by garlic and ginger.

The substance now called warfarin was first discovered in the
Warfarin was first discovered in spoiled sweet clover
1920s when American and Canadian cattle started dying from a mysterious bleeding disease. After some medical sleuthing, scientists discovered that the stuff causing the disease came from some fermented sweet clover in the cattle feed.

This mysterious substance prevented vitamin K from forming blood clots, so the cattle would die from minor cuts and abrasions or develop internal bleeding.

It wasn't until 1940 that scientists at the University of Wisconsin isolated the anticoagulant that caused the bleeding and gave it a name: dicoumarol.
Coumarin makes new-mown grass smell sweet


This powerful anticoagulant is produced by a fungus acting on a plant molecule called coumarin. Coumarin is the substance that makes new-mown grass smell sweet. But if the grass is allowed to ferment, rather than dry, the fungus grows and produces dicoumarol.

After World War II, researchers at the University of Wisconsin patented the substance as "Warfarin," a name derived from the acronym WARF: (Wisconsin Alumni Research Foundation) and the suffix "arin" from coumarin.

Warfarin was first registered for use as a rodenticide in the US in 1948.

Rats soon became immune to Warfarin
Apparently it was very effective in killing rodents because it's odorless and tasteless, so the rats and mice would keep coming back for more until enough Warfarin accumulated in their bodies to do them in.

In 1954, Warfarin was approved for medicinal use. But patients have to be carefully monitored to make sure the right balance of Vitamin K is preserved. It can cause skin necrosis and "purple toe syndrome" if the dose is too high. It is risky enough that pregnant women are advised not to take it.

But it stopped working as a rodenticide because rats developed immunity to it. That led scientists to produce "superwarfarins" brodifacoum, diphenadione, chlorophacinone, and bromadiolone . These superwarfarins are marketed under a number of colorfully named brands like Pestoff, Ratshot, Mouser, Havoc, and the better known D-Con. 

Superwarfarins stay in the body much longer and reduce Vitamin K more quickly, so they are much more lethal. Like warfarin, they can be absorbed through the skin, so people need to use care in handling them.

Both warfarin and superwarfarin can kill humans. The Handbook of Pesticide Toxicology reports that a 32 year old man was murdered by being given warfarin for 13 days. Since the drugs are odorless and tasteless, they are easy to administer, but the killer has to stay around for at least a couple of weeks.

In 1988, two teenaged girls tried to murder their parents using the superwarfarin D-Con. But luckily the parents went for medical help for the symptoms before they succumbed to the poison.
It's not a good idea to add warfarin to your weed.


The American Journal of Hematology reported that some wildly misguided stoners have found that if they mixed superwarfarins like D-Con with their weed, it will extend their high. When they land in the emergency room with mysterious bleeding, they often don't disclose that they've been exposed to surperwarfarins, which makes treatment difficult.

One young Einstein in Utah decided that if smoking rat poison was good, eating it would be even better. He nearly died of the bleeding disorder before he admitted he had been munching on D-Con.
You'd need a lot of these to do in nasty old Aunt Augusta


But most poisoning with warfarin and its cousins is accidental. The good news is that if a person or pet takes it by mistake, they will achieve full recovery if they get to a hospital, where large doses of Vitamin K combat the action of the drug.

To the mystery writer, warfarin and its nastier cousins might provide some interesting plots. If the wealthy, bullying matriarch everybody is hoping will die is already taking warfarin for a medical condition, a little of the colorless, tasteless rat poison in her cocoa might make for the perfect murder. Hmmm.

What about you? Have you read a mystery where warfarin is used as a weapon? Can you think of a good plot for murder by warfarin? 

Here's a list of all the posts in the poison series

Part 25: Yew
Part 26: Toxic Relationships

Enjoy the post? Take a look at some of my books!

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Someone has shot aging bad-girl rocker Morgan Le Fay and threatens to finish the job. Is it fans of her legendary dead rock-god husband, Merlin? Or is the secret buried in her childhood hometown of Avalon, Maine?

Morgan's childhood best friend Dodie, the no-nonsense owner of a dilapidated diner, may be the only one who knows the dark secret that can save Morgan's life. And both women may find that love really is better the second time around. Think Beaches meets Fried Green Tomatoes at the Whistle Stop Cafe.

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