When Alexander Fleming left his lab at St Mary’s Hospital Medical School in London for a few weeks in 1928 he returned to find dishes in which he was growing bacteria had gone mouldy. Fleming noticed the area where the mould had grown was clear of bacteria as if the bugs had been destroyed by something in the growth.
This chance discovery led to the development of antibiotics which have saved tens of thousands of lives by preventing infection. However, penicillin is not the only miracle medicine that came about as a result of good fortune.
Now one of the most famous drug names in the world, Viagra has transformed the treatment of impotence and restored the love lives of many men. Yet the famous little blue pill was never intended to treat problems in the bedroom.
In the early Nineties scientists were actually developing it as a remedy for the heart condition angina because it seemed to boost blood flow through damaged arteries by dilating blood vessels around the heart.
Patients however reported an unexpected side effect, involuntary erections. It’s been reported that some even refused to hand their pills back at the end of the experiment.
Viagra has now been used by more than 30 million men around the world.
For many years quinine has been one of the main drugs used to combat malaria, a disease that kills one million people a year. Yet its discovery was a complete accident.
Legend has it that a South American native, suffering a malarial fever and desperate to quench his thirst, drank from a bitter-tasting pool of water high in the Andes. Next to the small pool were some cinchona trees, the bark of which, it turned out, was packed with quinine.
When the man’s fever broke others began using the tree as medicine and it eventually became a major weapon against the deadly disease.
The accidental discovery of one of the first major anti-cancer drugs, cisplatin, was the result of what was initially thought to have been a botched experiment.
Researchers were studying what happened to living cells when exposed to an electric field. They tried to grow the E. coli bug in a field produced by a platinum electrode but the attempt failed.
The scientists reportedly spent a year checking their equipment and repeating the tests before they realised a reaction caused by the platinum in the electrode was killing the bacteria. They concluded that it might also kill cancer cells and the result was a drug now used to treat tumours such as testicular cancer.
Hair loss drugs
Regaine, a rub-on lotion, has emerged as a major treatment for male hair loss but it actually began life as a tablet for high blood pressure.
When researchers were testing it on patients they began to notice some were sprouting hairs on their heads, hands and neck.
So a drug meant to lower blood pressure by dilating blood vessels was, courtesy of its side-effects, reformulated into an over-the-counter lotion to cure hair loss.
Nitrous oxide, which is better known as “laughing gas”, has been used as an anaesthetic in medicine for over 150 years.
First discovered in 1793, no one realised it could block pain and travelling shows used to make money from customers who paid to inhale the gas to make them giggle.
In 1844 an American dentist called Horace Wells was at such a show in Connecticut when he noticed a man who cut his leg falling from the stage felt no pain until the gas wore off. The next day Wells experimented with the gas while having one of his teeth removed, paving the way for a breakthrough in pain control.
Millions of people round the world have taken antidepressant drugs known as tricyclics to combat their mood swings. However, the drugs nearly ended up on the scrap heap.
A Swiss psychiatrist called Roland Kuhn had been testing an early form of the drugs in schizophrenia with little benefit.
About to abandon the project, he gave some pills to a patient with severe depression and noticed a dramatic improvement in the patient’s mood.
Pure chance led to the discovery of digitalis, a heart remedy that was used for nearly 200 years until newer drugs came along.
In 1776 country doctor William Withering said there was nothing he could do for a woman dying from dropsy, or swelling of body tissues due to an ailing heart. He later heard she had recovered after taking a remedy made from a garden plant called foxglove.
Scientists later found foxglove, which is poisonous in high doses, got rid of excess fluids. It was turned into the drug digitalis.