The effectiveness of anti-clotting pill ticagrelor is now under a cloud, with some experts claiming that AstraZeneca misreported data when the trials were conducted more than a decade ago.
Sold as Brilinta, the pill was approved for use on the NHS in 2011 after trials claimed it could prevent one in five deaths after a heart attack, and the generic versions of the drug are scheduled for this year.
The AstraZeneca drug is given to people with acute coronary syndrome, a sudden reduction in the flow of blood to the heart.
Last December, a British Medical Journal (BMJ) investigation found data discrepancies during the crucial clinical trials that were used to gain worldwide approval for ticagrelor.
The BMJ is now looking into the two key platelet studies in the phase 2 trials that AstraZeneca claimed show ticagrelor's ability to treat acute coronary syndrome successfully.
BMJ found that the "primary endpoint" results (the trial's key measurement) for both clinical trials were inaccurately reported in the journal Circulation, and more than 60 of 282 readings from platelet machines used in the trials were not present in the US Food and Drug Administration (FDA) datasets.
Dr Victor Serebruany from Johns Hopkins University told BMJ, "If doctors had known what happened in these trials, they would never have started using ticagrelor."
He said it was "unconscionable" that the FDA leadership failed to see it, and now it has been discovered by BMJ.
The platelet studies were led by cardiologist Dr Paul Gurbel from Sinai Center for Thrombosis Research and Drug Development.
The institute dismissed the allegations as "baseless and erroneous".
In the UK, the drug is prescribed around 45,000 times per month on the NHS.
According to the medicines watchdog, the National Institute for Health and Care Excellence (NICE), patients are advised to take the drug after a heart attack.
It is also taken by those who have suffered a minor stroke or a transient ischaemic attack.
