Pradax (dabigatran) was approved in 2011 in Europe, and a year earlier in the US, on the basis of just one study, even though the regulators were concerned about the way it had been put together.
And a new investigation has discovered that the manufacturer held back on some of the data, and never disclosed it to the US's Food and Drug Administration (FDA) or the European Medicines Agency.
Within a year of its approval, concerns were already being raised about cases of fatal bleeding, and the manufacturer was privately worried about dosage levels, although these fears were never shared with the regulators.
Dabigatran is one of the new generation of oral anti-coagulants, or blood thinners, that are designed to prevent stroke in people with atrial fibrillation, or irregular heart rhythm.
(Source: British Medical Journal, 2014; 349: g4681)