Blood thinner report from the FDA

Comparing the thrombin inhibitor Pradaxa (dabigatron) to the vit K inhibitor and old standby, warfarin (Coumadin), the research results were mixed. Not impressive.

Dabigatron is promoted as easier to use, no INR tests every 2 or 3 weeks.

I would call the benefits report mildly positive for a very expensive drug, and the risk profile a little worse for major intestinal bleeding. No slam dunk for sure for the new, very expensive dabigatron (Pradaxa).

FDA Releases Safety Data on Dabigatran Bleeding Risks Relative to Warfarin
Frontline Medical News, 2014 May 13, E Mechcatie News

Current recommendations and labeling regarding the use of dabigatran will not change, based on the results of a large observational cohort study comparing the risks of the direct thrombin inhibitor and warfarin in Medicare recipients, the Food and Drug Administration announced on May 13.

The study, which was completed recently and has not been published, found that dabigatran, compared with warfarin, was associated with a lower risk of ischemic stroke, intracranial hemorrhage, and death, according to the FDA’s statement on the findings. The risk of major gastrointestinal bleeding, however, was higher with dabigatran, and the risk of myocardial infarction was similar in both groups.

The statement points out that other than the MI finding, the results are consistent with the results of the RE-LY (Randomized Evaluation of Long-Term Anticoagulation Therapy) trial, which found the MI risk was higher among those on dabigatran than with warfarin. Approval of dabigatran in 2010 for reducing the risk of stroke and systemic embolism in patients with nonvalvular AF was based on the results of the RE-LY study. Dabigatran is marketed as Pradaxa by Boehringer Ingelheim.

“As a result of our latest findings, we still consider Pradaxa to have a favorable benefit to risk profile and have made no changes to the current label or recommendations for use,” the FDA statement said. “Importantly, the new study is based on a much larger and older patient population than those used in FDA’s earlier review of postmarket data, and employed a more sophisticated analytical method to capture and analyze the events of concern.”

The study, part of an ongoing review of dabigatran, evaluated the risks of more than 134,000 new users of dabigatran and warfarin, who were over age 65 years and had been diagnosed with atrial fibrillation during the 6 months before the medication was dispensed. The data were from 2010-2012. Patient outcomes were identified in administrative and insurance claims, and the study represented more than 37,500 person-years of follow-up.

The results were as follows, with warfarin as the reference group, and dabigatran results based on the analysis of both approved doses (75 mg and 150 mg) combined:

• For ischemic stroke, the incidence rates (IR) per 1,000 person-years were 11.3 for dabigatran, vs. 13.9 for warfarin (hazard ratio, 0.80).

• For intracranial hemorrhage, the incidence rates were 3.3 for dabigatran, vs. 9.6 for warfarin (HR, 0.34).

• For major GI bleeding, the incidence rates were 34.2 for dabigatran, vs. 26.5 for warfarin (HR, 1.28).

• For acute MI, the incidence rates were 15.7 for dabigatran, vs. 16.9 for warfarin (HR, 0.92).

• For mortality, the incidence rates were 32.6 for dabigatran vs. 37.8 for warfarin (HR, 0.86).

The FDA statement points out that the results for major GI bleeding in this study are different from a previous FDA analysis of about 10,600 new users of dabigatran and warfarin, reported in 2012, which found that GI and intracranial hemorrhage rates were lower among patients treated with dabigatran, compared with those on warfarin. However, that study included patients under age 65 years (64% were older than age 65 years), and this disparity “may reflect the age differences in the two patient populations,” the FDA statement said.

The FDA plans to publish the Medicare study and will continue to review the risks of bleeding with anticoagulants.

Dabigatran is now also approved for the treatment of deep venous thrombosis (DVT) and pulmonary embolism (PE) in patients who have been treated with a parenteral anticoagulant for 5-10 days, and to reduce the risk of recurrence of DVT and PE in patients who have been previously treated.

The FDA has issued two previous safety alerts regarding the bleeding risks associated with dabigatran, in 2011 and 2012.

The FDA notice is available here. Serious adverse events associated with dabigatran and warfarin should be reported to the FDA at 800-332-1088 or at MedWatch.

3 responses to “Blood thinner report from the FDA

  1. Ask your Doctor about how to reverse the drugs effects if you fall down or are involved in a accident . . Warfarin can be reversed with a simple injection. the new drug must be put through a blood cleaning system like is used for artificial kidney treatments . . if you are not close to a facility with the filtering equipment you could die.

    INR tests with the patient watching their diet can be extended to once a month. I am tested once a month and have not changed my dosage for over a decade.

  2. Profitup, your point is very important. We do not have an antidote for bleeding with Pradaxa–promised from European sources, but blood products replacement is the only treatment right now.

    That was my initial disloke of Pradaxa because nothing worse than uncontrolled bleeding to make an emergency doc have gray hair–woops, already have grey so it’ll probably fall out.

    • With millions having atrial fibrillation the risk is real and many will most likely die before the issue is solved. My Cardiologist has A fib he asked me if I had heard of the new drug and I said yes – I have read the reports and studies.

      He then looked at me and said I would not take it either.

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