Statins have been around for 20 years but it is only in the past five that their use in Britain has expanded fast.

The growth has been fuelled by trials that show they can cut deaths from heart disease by at least a quarter, and because they are relatively cheap and very safe.

As heart disease remains our second biggest killer after cancer, even a healthcare system as reluctant to spend money on drugs as the NHS can see that this is a one-way bet.

Much of the effort now is not to ensure that patients who can benefit get the drugs, but that they get the cheapest one. Simvastatin is out of patent and a 40mg dose is reckoned the equivalent of 10mg of Lipitor, the more expensive branded market leader.

So patients all over the country are being switched by their GPs. The Department of Health says that this switching policy had saved the NHS £77 million in the past year.

The statin data are certainly impressive. Trials show that in people with heart disease, statins cut death rates from all causes by 21 per cent, deaths from heart disease by 28 per cent, and further non-fatal heart attacks by 31 per cent.

In those without clinical evidence of heart disease, the results are more equivocal. One study showed that death rates were reduced by 17 per cent, but this was on the edge of statistical significance.

Statins first emerged from laboratories in the late 1970s and early 1980s. Relatively few people then were convinced that lowering cholesterol levels would have much effect on heart disease, but a few companies nevertheless started research programmes.

Among them was Merck, which assigned a biochemist called Alfred Alberts to the job when he joined the company in 1975. He had little idea where to start but as an inspired guess gathered a few fungal extracts that had been rejected by a Merck laboratory in Spain as antibiotics, and tested them against the enzyme that makes cholesterol.

The first 17 failed but the eighteenth was so effective that the chemist responsible thought she had made a mistake. She hadn’t — it really did work. An active extract that became Mevacor, the first successful statin, was produced in 1978.

But it wasn’t until 1987 that Mevacor was licensed. Together with Zocor, a slightly modified version, it has earned billions of dollars for Merck.

Pfizer’s Lipitor was discovered in the mid-1980s and was the fifth statin on the market. Parke-Davis (now part of Pfizer) thought at first that Lipitor might be little better than the other statins. But champions within the company persuaded management to carry out human trials, from which Lipitor emerged as better than the existing statins. Today it is the world’s best-selling drug, by a big margin.

As the new trial implies, statins do more than simply lower cholesterol. Most people imagine that heart attacks occur when the arteries get furred up, but in reality the event that triggers them is the breaking away from the artery wall of plaques, which then block the blood vessels and starve the heart of blood.

Statins appear to stabilise the lining of the blood vessels, as well as damping down inflammation. These effects, unanticipated at the time the drugs were developed, contribute hugely to their effectiveness. Statins work even on those whose cholesterol levels are normal.

It is studies like these that encouraged the National Institute for Health and Clinical Excellence (Nice) to recommend the wider use of statins in outwardly healthy people.

No drug is entirely without risks and there are GPs who believe these are being greatly underestimated. There are two serious side-effects: irritation of the liver, and damage to muscle cells, called rhabdomyolysis. Both are rare.

In the trials, says Nice, there were six non-fatal cases of rhabdomyolysis among 47,000 users of statins, compared with half as many among 47,000 controls. Millions of people are now on statins, so it is no surprise that a few have suffered these side-effects.

It is as clear as it could be that for those at elevated risk of heart disease — for whatever reason — statins are the right prescription.

The problem is that many will stop taking them almost as soon as they start. Within a year, half will have given them up, because there is little motivation to keep taking a medicine whose effects are imperceptible.

Fortunately the new study suggests that even those who give up will have had some benefit, assuming they have several years of use behind them.

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