A "polypill" combining a statin with blood pressure drugs could prevent thousands of heart attacks and strokes every year, according to researchers.
A UK study of 84 over-50s, published in the journal PLoS One , showed the pill could cut blood pressure and levels of "bad" cholesterol.
They called for the pill to be made available "as a matter of urgency".
The British Heart Foundation called for more research and said pills were not a substitute for a living a healthy life.
This study at Queen Mary, University of London investigated a polypill containing a statin and three blood pressure drugs, all of which are already widely used.
Patients were given either a polypill or a dummy pill once a day for three months. Their treatments were then swapped so that over a six-month period they would have spent half the time taking the drug and half the time taking the sugar pill.
The results suggested the polypill reduced blood pressure by 12% and LDL cholesterol by 39%.
Dr David Wald, consultant cardiologist, said: "The health implications of our results are large.
"If people took the polypill from age 50, an estimated 28% would benefit by avoiding or delaying a heart attack or stroke during their lifetime."
The doctors calculated that if half of the over-50s in the UK took the daily pill, it would prevent 94,000 heart attacks and strokes each year.
Dr Wald said the trial represented a "milestone" and called for regulatory bodies to approve the polypill "urgently".
European and Canadian patents for a polypill are held by David Wald's father, Prof Nicholas Wald.
The study did not test the safety of the drug, but the researchers say all the components of the polypill have been used for decades.
The British Heart Foundation's senior cardiac nurse, Natasha Stewart, said: "Research into polypills is encouraging, but there are still many questions to answer before this 'wonder drug' is prescribed by doctors.
"This research only studied a very small number of people, so we'd need to see further large scale trials on a wider population to get more detailed results.
"However interesting this potential new pill is, medicines are not a substitute for living a healthy lifestyle. Staying active, eating healthily and not smoking are still vital ways to help keep your heart in good shape."
The polypill does not contain aspirin, which is already taken by some people to reduce their chances of a heart attack or stroke. It is thought the risk of causing internal bleeding outweighed those benefits for people with no history of cardiovascular disease.
Helen Williams, cardiac medicines spokesperson for the Royal Pharmaceutical Society, said: "This very small study demonstrates that such a pill does have the expected effect on these risk factors, however a much larger study would be needed to show the impact of these changes in blood pressure and cholesterol on cardiac events, and also to demonstrate the overall safety of exposing large numbers of essentially healthy people to these medicines.
"Whilst these results are promising, further research is needed before a wide scale rollout of such a strategy."