Aspirin – the drug widely used to deal with hangover headaches and many other minor illnesses – was developed in Germany by a chemical process described by research chemist Felix Hoffman on October 10, 1897. Decades later it is still the most versatile and effective medicine on the pharmacist’s shelf. But as doctors are now increasingly recognising, the drug does not just relieve aches and pains, it can also prevent a wide range of serious, life threatening conditions.
The active ingredient in aspirin, acetyl salicylic acid, is a synthetic derivative of a compound, salicin, which occurs naturally in plants, notably the willow tree. Extracts of willow were traditionally used in folk medicine and as early as 400 BC the Greek physician Hippocrates recommended a brew made from willow leaves to treat labour pains. Later in 1763 an English clergyman, Reverend Edward Stone carried out the first proper scientific study of the herbal medicine when he described the benefits he observed after giving ground up willow bark to 50 parishioners suffering from rheumatic fever.
However, when the active ingredient salicin was converted to the medicine salicylic acid it was hard to swallow, causing irritation to the lining of the mouth and stomach. Then in 1897 Felix Hoffmann of the Bayer pharmaceutical company developed the process of synthesising the acetyl salicylic acid named later as aspirin.
In early clinical trials aspirin was found to be a potent treatment for pain, fever and inflammation. Today it is the best known and most widely used medicine in the world with an estimated 100 billion tablets swallowed every year. Indeed it is also used out of this world - as every Space Shuttle carries a small supply.
But how aspirin works was a mystery until comparatively recently. During the 1970s the British scientist Professor John Vane discovered that it blocked an enzyme needed for the production of natural hormones called prostaglandins involved in many body processes including pain and tissue injury. In 1982 Professor Vane, now Sir John Vane, won the Nobel Prize for Medicine for this work.
Yet even now biomedical scientists are still finding out more about the effects of aspirin in the body and their discoveries are opening up further possibilities for future clinical applications. Probably the most significant of these is its role in preventing the production of the prostaglandin thromboxane, which is a vital link in the process which leads to the formation of blood clots.
Small daily doses of aspirin may therefore help prevent diseases such as heart attack, stroke and the blindness and kidney damage suffered by many patients with diabetes. Here the damage is caused by clots blocking a major blood vessel. There have been many trials to test the long term benefits of using aspirin as a preventive medicine. Dr Colin Baigent, one of the doctors involved, has claimed that more widespread use of aspirin at low doses could save up to 100,000 lives year around the globe.
Like heart disease and stroke, bowel cancer is one of the biggest causes of death in Western Europe. One in 35 people will contract the disease and 1 in 50 will die unless more effective treatments are found. aspirin may be part of the answer. A study which examined the health of nearly 90,000 American nurses from 1976 to 1995 showed that in those who regularly took aspirin the risk of getting colon cancer dropped by a half. Doctors don't yet know how aspirin works here although it is possible that the drug affects the growth of small polyps on the bowel wall. Prostaglandins seem to be involved in this process. The growths may turn malignant in some forms of the disease and aspirin appears to prevent this.
Aspirin also has a protective
effect in diseases affecting both ends of the age scale. Two of
the most important causes of complications during pregnancy - foetal
growth retardation and pre-eclampsia - are thought to be caused
by blood clots in the arteries serving the placenta. Regular doses
of aspirin may help keep those blood vessels open.
This allows the foetus to receive the nutrients it needs to grow and prevents the rise in maternal blood pressure which occurs in pre-eclampsia and which can cause kidney damage, convulsions and death.
Similarly in the very old, some forms of dementia are caused by blockages of the blood vessels in the brain. There is some preliminary evidence that aspirin may reduce the severity of brain damage allowing sufferers to lead longer and fuller lives. However, as with the other new therapeutic applications of aspirin the evidence is incomplete. Further trials are in progress.
Equally importantly it will be necessary to find out if long term treatment with aspirin does any harm. As the drug has been used so widely and for so long this may seem unlikely but as with all medicines there are always some risks. So far the only proven side effects of aspirin use are remarkably minor. About six per cent of patients suffer some form of indigestion and about one in 500 may get an allergic reaction usually itching. In some people it may also cause mild bleeding from the lining of the stomach and patients with gastric ulcers are told to use some other form of painkiller.
Most of the drugs which would have been found alongside aspirin in a Victorian pharmacy have long since disappeared, replaced by newer and more effective drugs. But aspirin goes from strength to strength. And given the pace of current research into new uses for the drug it seems likely that it will still be available long into the next century.
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