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Study of Pradaxa and Xarelto Side Effects Shows Twofold Risk of Bleeding over Warfarin

xarelto pill bottleResearchers at Johns Hopkins are suggesting that the use of two popular “new generation” blood thinners may run as much as twice the risk of gastrointestinal bleeding as the drug they are trying to replace.

Despite recent research that has established that Pradaxa and Xarelto carry a significant increase in risk of gastrointestinal bleeding over their predecessor, warfarin, the manufacturers of the relatively new drugs continue to tout the convenience of their medications as requiring less frequent blood monitoring.

Pradaxa and Xarelto side effects highlighted in study

The study, published by the British Medical Journal (BMJ) in their April 24 installment, examined data on 46,000 patients who were prescribed Coumadin (warfarin), Xarelto (rivaroxaban), and Pradaxa (dabigatran) from October 2010 to March 2012. It established that Xarelto may carry up to twice the risk of internal bleeding as warfarin and Pradaxa up to 50% more risk.

In light of the increased risk of bleeding, a second downside of the two medications becomes even more ominous. Unlike warfarin, neither Xarelto nor Pradaxa have an antidote or reversal agent if a bleeding event begins, so doctors have no means to control the bleeding once it’s started. On the other hand, doctors using warfarin for their patients have reversal agents available that can quickly stop a bleeding event at its inception.

Pradaxa and Xarelto side effects not obvious at first

Both Pradaxa and Xarelto have been lightning rods for controversy since their introduction as anticoagulants of the future. Heralded by their manufacturers as the first convenient, monitoring-free blood thinners to prevent strokes in patients with atrial fibrillation, they appeared poised to unseat the market share leader, warfarin, which requires regular blood monitoring.

Pradaxa by Boehringer Ingelheim reached the market first in 2010, seizing the attention of physicians and their patients who were looking for a less rigid monitoring protocol than warfarin. Within a year, it began to go wrong for Pradaxa, with thousands of reports of severe and uncontrollable bleeding events earning it a reputation as a drug to avoid.

Boehringer Ingelheim soon became mired in over four thousand Pradaxa lawsuits by patients who claimed that they were not made aware of the inherent risks in using the drug or that there was no reversal agent in the event of a gastrointestinal bleed. Despite its protestations of innocence, the manufacturer agreed to a $650 million settlement to end the litigation.

Approved in the end of 2011, Xarelto, manufactured by Janssen Pharmaceuticals, tried to seize the moment and step into the vacuum created by Pradaxa’s troubles. It temporarily rose to the top of the anticoagulant market by 2013 but was soon beset into 2014 by a tide of Xarelto lawsuits alleging deadly complications.

Study unable to rule out increased risks of bleeding with Xarelto

Although researchers note that there was no significant difference in bleedings risks between warfarin users and those using Pradaxa and Xarelto, they were unable to rule out that both drugs may carry increased risks of bleeding over warfarin due to the difference in the study populations.

“Although rates of gastrointestinal bleeding seem to be similar in this commercially insured sample of adults in the United States, we cannot rule out as much as a 50% increase in the risk of gastrointestinal bleeding with dabigatran compared with warfarin or a more than twofold higher risk of bleeding with rivaroxaban compared with warfarin,” they concluded.

Both Boehringer & Ingelheim and Janssen researchers still hope to find an effective reversal agent for their Pradaxa and Xarelto products. It was announced last week by B & I that the FDA has granted a fast-track review for a possible Pradaxa reversal agent.

  1. BMJ, British Medical Journal, Comparative Risk of Gastrointestinal Bleeding with Dabigatran, Rivaroxaban, and Warfarin: population based cohort study,
  2. Todays’s Hospitalist, No Antitode: Reversal Strategies for Newer Anticoagulants,