A scandal is emerging around the anticoagulant drug dabigatran, marketed as Pradaxa.

The drug has been welcomed by many in the medical community as it cuts the need for regular blood tests, which were required to monitor blood-thinning Warfarin.

But according to a British Medical Journal investigation, drug-maker Boehringer Ingelheim is withholding documentary evidence that blood tests reduce major bleeds among patients taking Pradaxa.

Researchers say the drug’s vacillating pharmacokinetics can cause a five-fold variation of plasma concentration. This would put patients with atrial fibrillation at risk of serious bleeding, or open others to increased stroke risk.

Concern has been raised about the regulatory approval of Pradaxa, a PBS-listed drug, as evidence now suggests the regulatory guidelines are incomplete.

The BMJ accuses Boehringer Ingelheim of putting marketing ahead of safety by holding on to information that could have hampered its popularity.

But the Therapeutic Goods Administration says it is aware of the journal article, has undertaken two safety reviews into the drug, and will continue to monitor its safety.

Figures published by the ABC suggested Pradaxa has been linked to 280 deaths and 1,400 adverse drug reactions in Australia over the past five years.

These have included including abdominal bleeding, brain haemorrhages, strokes and heart attacks.

It predecessor and main competitor, Warfarin, is associated with 30 deaths and 270 reactions in the same period.

Boehringer Ingelheim says it is not withholding important data.

The drug-maker said in a statement that the suggestion of improving safety through regular blood level monitoring was a hypothesis it disproved in 2012.

They said the data from mathematical models of regular blood testing did not match that from its major clinical trial, and so it was never released.

But the BMJ investigators say they found internal emails from US court proceedings, and a draft version of the journal article, which paint a different picture.

The draft article said an “optimal plasma concentration” range could be achieved with blood monitoring, but subsequent emails between the medical team showed one key member was “not happy with the conclusion” about an optimal range.

“The publication [of the article] will [do] more harm than be useful for us, neither in the market but especially harmful in the discussions with regulatory bodies,” another company official write in an email.

It is possible that the story will hit mainstream Australian news networks this week, and specialists say patients must be warned not to stop taking Pradaxa, as this can bring on the risk of stroke.