Medical Alert: Pradaxa Stroke & Bleeding Injuries

The Institute for Safe Medication Practices (ISMP) released its fourth quarter 2010 adverse drug event report, which highlighted safety concerns surrounding the number of adverse event reports submitted to the FDA involving Pradaxa. Pradaxa (dabigatran) was only released in October 2010, but the ISMP notes that there were more consumer complaints to the FDA’s MedWatch adverse event reporting system during the first three months the anti-clotting drug was available than 98.7% of the other drugs the organization monitors.

Some patients and doctors reported that it sometimes had too much of an effect on clotting, leading to hemorrhages. Other reports indicated that at times it did not have enough of an effect, resulting in pulmonary embolism or deep vein thrombosis.

The ISMP reports that hundreds of complaints about the Boehringer Ingelheim drug were sent to the FDA, with the agency receiving 307 complaints about Pradaxa problems during the last quarter of 2010. Most of the cases were of bleeding problems in elderly users. The drug is meant to be a replacement for warfarin, which was associated with only 202 adverse events in the same time period.

The drug was only approved by the FDA for the prevention of stroke in patients with atrial fibrillation, but the ISMP report indicates that doctors are already beginning to use it extensively off-label as a general-use anticoagulant. Only about one-third of the prescriptions so far have actually been for the FDA-approved purpose.

The FDA has approved Pradaxa, a new drug to prevent blood clots in patients with atrial fibrillation. Pradaxa's generic name is dabigatran etexilate. It is made by Boehringer Ingelheim Pharmaceuticals. Pradaxa can have adverse effects, including life-threatening bleeding.

In September 2011, Pradaxa became the subject of an investigation in New Zealand after as many as five elderly Pradaxa patients reportedly died as a result of internal bleeding. Another 36 patients reportedly suffered bouts of serious internal bleeding. New Zealand media outlets reported that some families claimed the chain of events leading to their relatives' deaths began when they switched from warfarin to Pradaxa, and infections set in after their conditions had deteriorated to the point of hospital admission.

The New Zealand reports came weeks after regulators in Japan asked the maker of Pradaxa to notify doctors about potentially deadly bleeding in some Pradaxa patients. According to a letter sent to Boehringer Ingelheim by the country's health ministry, between March 14 and August11, 81 elderly patients taking Pradaxa suffered heavy bleeding, leading to five deaths. Japanese officials suggested that patients older than 70 may need a lower dose of Pradaxa. Bleeding is also a side effect of older blood thinners, such a warfarin. But warfarin bleeding can be treated with vitamin K. There is no antidote available for bleeding caused by Pradaxa and similar drugs, known as direct thrombin inhibitors.

Dabigatran is used to help prevent strokes or serious blood clots in people who have atrial fibrillation. Dabigatran is in a class of anticoagulant medications called direct thrombin inhibitors. Thrombin is one of many clotting factors in the body necessary for coagulating blood.

Atrial fibrillation is a heart rhythm disorder caused by a malfunctioning electrical conduction system within the heart. It is an irregular rapid heart rate that begins in the smaller 2 upper heart chambers, known as the atria, that begins to contract quickly and in an irregular fashion. As electrical signals leave the atria and enter the ventricles, they too begin to contract quickly and in an irregular fashion. This irregular and rapid heart rate is unable to pump the blood through the heart and out to the body. Blood can pool in the heart and the lower extremities allowing clots to form. These clots dislodge and travel to the heart, lungs, and brain leading to a stroke.

Its estimated 2.3 million Americans have atrial fibrillation and the number is expected to increase to 5.6 million by 2050. Atrial fibrillation increased the risk of stroke 5 times, and is an underlying condition in 15% of all US strokes. Atrial fibrillation related strokes are twice as likely to be fatal or severely disabling when compared to strokes from other causes.