STUMBLING ON SUCCESS: Drugs discovered by accident

STUMBLING ON SUCCESS: Drugs discovered by accident

Just as new words are coined and old ones evolve, so too does medical science evolve and improve in a non-linear fashion.

In fact there are many great discoveries in medicine which resulted from strange or unfortunate circumstances, or which ended up having very different applications to those originally intended.

For example:

Viagra (sildenafil citrate): One of the most famous modern accidental medical discoveries. The fastest selling drug of all time, this medicine is taken for erectile dysfunction, but it was originally prescribed for treatment of hypertension and angina. It is also used off-label as a cure for jet-lag! The drug is not without risk, however, as excessive use may cause deafness and/or blindness.

Minoxidil: This antihypertensive vasodilator medication was originally being tested on dogs as a treatment for ulcers. It failed to treat the ulcers, but instead was authorised by the FDA for testing as a treatment for hypertension, due to its powerful vasodilating properties. Subsequent studies with minoxidil showed unexpected hair growth in subjects, and today it is successfully used as the active ingredient in popular hair loss treatments.

Mustard gas (sulphur mustard): This blister-causing chemical is well known as a horrendous and damaging chemical warfare agent. However, did you know that tests on the white blood cell counts of mustard gas victims ultimately led physicians to discover its value as therapy for Hodgkin’s lymphoma? Eventually, a similar compound (nitrogen mustard) became the first cancer chemotherapy drug, marketed as Mustine.

Penicillin was among the first medicines to combat bacterial infections. Various scientists had noticed the curative properties of mould, and in 1928 Alexander Fleming reported that under the right conditions, Penicillium rubens would exude a substance with antibiotic properties. It is now the most commonly used antibiotic in the world!

Warfarin ‑ in the 1920s it was the scourge of livestock farms in North America and Canada and was later used as rat poison. Post-Depression farmers in North America and Canada, in those austere times, began letting their cattle graze on damp/mouldy sweet clover hay which in more affluent times would have been discarded. After previously healthy cattle began to die from bleeding, they discovered that coumarin found in the hay was to blame for what they had come to know as “sweet clover poisoning”. In 1948, it became used as a rodenticide, and was patented as “Warfarin”. Then in 1958, it was administered to General Dwight Eisenhower who had just suffered a myocardial infarction, and later proved in clinical trials to increase survival following deep venous thrombosis and pulmonary embolism. Today it is the most widely prescribed oral anticoagulant drug in the US - all thanks to those few unfortunate cattle back in the 1920s! There is now a new generation of anticoagulants (factor Xa inhibitors and direct thrombin inhibitors) which are proving to have some advantages for patients over warfarin.

Do you have any favourite drug discovery stories to share?