A lot of caution and care is taken when a doctor prescribes a medication and a pharmacy orders said prescription to be delivered to your door, as ensuring the right medicine in the right dose is vital to treating any condition.

There is an adage, originally attributed to Paracelsus but has changed many times over the years that says that “the dose makes the poison” (Sola dosis facit venenum in Latin).

The idea is that too much of a medicine can be harmful or even potentially deadly, whilst in some cases trace amounts of poisons can be beneficial. In modern medicine, this concept is known as the therapeutic index.

Another way this is described is that whilst we need water to live, too much will cause us to drown.

There are some very literal examples of this in action, but one of the most famous is how a rat poison became a commonly prescribed medication that saved the life of a United States President.

The Paradox Of Warfarin

Often described incorrectly as a blood thinner, warfarin is an anticoagulant that helps to break down blood clots where they already exist and prevent future ones in people who have replacement heart valves, irregular heartbeats or conditions such as thrombophilia.

This exact property makes it one of the most carefully controlled medications prescribed, and the dose can change depending on diet, other medications and other illnesses. Otherwise, it could either be ineffective or cause too much bleeding.

This exact property is why warfarin was initially produced, marketed and sold as rat poison in 1948, working remarkably well for the purpose.

However, the main purpose of the drug changed dramatically after a potentially tragic incident in 1951.

A man who had been inducted into the United States attempted to take his own life by swallowing several doses of warfarin. However, after being given vitamin K, a known antidote also known as phytomenadione, the young soldier made a complete recovery.

This near-tragedy managed to provide a lot of medical information on the effects of warfarin in the human body and led to several doctors wondering whether it could be as effective as dicoumarol as an anticoagulant.

Both originated as a byproduct of mouldy sweet clover and by 1954, both were approved for use to treat a range of heart and blood conditions, which led to warfarin’s most famous patient.

United States President Dwight D. Eisenhower suffered a heart attack in 1955, just two years after he was sworn in, and there were concerns that he might be unable to serve the entirety of his first term, let alone a second one.

Ultimately, he was prescribed warfarin, and made a remarkable recovery, allowing Ike to run for president and win in an even bigger landslide in 1956, serving out the remainder of his term with few health issues.

He would remain on warfarin for much of the rest of his life, dying at the age of 78 in 1969, but also being a very prominent example of how medication cannot be judged on its first use or first appearance.