A drug used by transplant patients can extend the lives of mice by about a third, according to research that raises the prospect of a life-prolonging pill for people.

Male mice given rapamycin lived on average 28 per cent longer than a control group of animals, while the effect on females was greater still, with a 38 per cent increase in life expectancy. The animals were treated at an age of 20 months, which is the equivalent of 60 years in humans.

The study, led by David Harrison, of the Jackson Laboratory in Maine, is the first to identify a drug that can lengthen the lives of mammals, and suggests that similar medical techniques might be capable of doing the same thing in people.

Scientists warned, however, that nobody should take rapamycin in the hope of living longer. The drug, originally identified in soil samples from Easter Island, is a powerful suppressor of the immune system, commonly given to patients to help to prevent the rejection of transplanted organs, and its dangers to healthy people would far outweigh any potential benefit.

The hope is that rapamycin’s effects might highlight biological pathways involved in the ageing process, which could then be targeted with a safer drug. Details of the research are published in the journal Nature.

Randy Strong, of the University of Texas and a member of the study team, said: “We believe this is the first convincing evidence that the ageing process can be slowed and lifespan can be extended by a drug therapy starting at an advanced age.”

Matt Kaeberlein and Brian Kennedy, of the University of Washington, wrote in a commentary on the work: “Certainly, healthy individuals should not consider taking rapamycin to slow ageing. The potential immunosuppresive effects of this compound are sufficient to caution against this.

“It may be possible to develop pharmacological strategies that provide the health and longevity benefits without unwanted side effects.”

Lynne Cox, researcher in ageing at the University of Oxford, said: “This is a very exciting study. It is especially interesting that the drug was effective even when given to older mice — equivalent to 60-year-old humans — as it would be much better to treat ageing in older people rather than using drugs long term through life. What the study does is to highlight an important molecular pathway that new, more specific drugs might be designed to work on.”

Research into the ageing process has previously identified two mechanisms that can prolong mammalian lifespans, but neither is easily applicable to humans. Mice are known to live longer if fed a calorie-restricted diet that is close to starvation levels, but this would be very difficult for a person to maintain. The other option is genetic manipulation.

Dr Harrison’s team began to investigate rapamycin because it seems to affect the same biological pathway as calorie restriction, making it a candidate for anti-ageing therapy. The drug, which takes its name from Easter Island’s Polynesian name, Rapa Nui, is used to tone down the immune system of transplant patients so that their organs are not rejected, and to improve the performance of stents implanted to keep arteries open. It has also started trials as a cancer therapy.

Arlan Richardson, director of the Barshop Institute at the University of Texas, which contributed to the research, said: “I’ve been in ageing research for 35 years and there have been many so-called ‘anti-ageing’ interventions over those years that were never successful.

“I never thought we would find an anti-ageing pill for people in my lifetime; however, rapamycin shows a great deal of promise to do just that.”

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