Blood-thinner Pradaxa linked to uncontrollable bleeding, death

Concerns about prescription blood-thinning medication Pradaxa increased recently, when a Utah man died within hours after falling and hitting his head. Doctors discovered he was hemorrhaging in his brain and could not stop the bleeding. The man had been taking Pradaxa for about one month. According to the case study in the Journal of Neurosurgery, “There is currently no effective antidote to reverse the anticoagulant effect of dabigatran (Pradaxa) in the event of an emergency.”

Pradaxa (dbigatran etexilate mesylate) is a blood thinning (anticoagulant) medication used to reduce the risk of stroke in patients with non-valvular atrial fibullation (AF), the most common type of heart rhythm abnormality. With atrial fibrillation, part of the heart does not beat the way it should. This may cause blood clots to form, increasing the patient’s risk of stroke.

Pradaxa was approved by the U.S. Food and Drug Administration (FDA) in October 2010 as an alternative to warfarin, which has been on the market for more than 50 years. Both are blood thinners, but Pradaxa is the first in a new class of oral blood-thinning medications called direct thrombin inhibitors.

Since its approval through August 2011, the FDA reports a total of 1.1 million Pradaxa prescriptions were dispensed and approximately 371,000 patients received Pradaxa prescriptions from U.S. outpatient retail pharmacies.

In November 2011, Pradaxa manufacturer Boehringer Ingelheim confirmed results of its clinical trials, which revealed 260 people worldwide who had suffered a fatal bleed while taking Pradaxa.

In December 2011, the FDA issued a Safety Announcement that it was studying whether reports of bleeding in patients taking Pradaxa are occurring more commonly than would be expected, based on the results of the clinical trial. European drug regulators also called for stronger warning labels on the drug, and drug regulators in Japan and Australia also are urging greater caution when prescribing Pradaxa.

The JNJ case study reports that because dabigatran is excreted primarily through the kidneys (renally), dialysis could possibly be used as a method to clear the drug from the body. However, the process is relatively slow, removing only about 35 percent to 60 percent of the drug in two to three hours. Also, this process itself is risky because patients with atrial fibrillation may suffer worsening heart function due to the stress of receiving an overload of fluids in this type of procedure.

Conversely, the effects of warfarin, which has been used for decades as a blood-thinner, can be reversed by administering fresh-frozen plasma, vitamin K, and clotting factor VII, the case study says.

Although the FDA strengthened the warning label for Pradaxa in January 2012, it did not give the drug a “black box warning,” which indicates the most serious risk of injury or death. The FDA also advises patients who are already taking the drug to continue their medication and to consult their doctor.

Meanwhile, other drug manufacturers are eager to jump into the warfarin-alternative market. Pfizer and Bristol-Myers Squibb are awaiting a decision on their Eliquis anticoagulant, and Bayer and Johnson & Johnson have proposed Xarelto for approval.

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Journal of Neurosurgery
Los Angeles Times
Fierce Pharma