However, attention is now being drawn toward one potentially serious problem with dabigatran -- if a major bleeding episode should occur on this drug, it can be especially difficult to assess and treat the bleeding.
The reason dabigatran has come into widespread usage so quickly is that it is at least as safe, at least as effective, and is much easier to administer than Coumadin, which was for decades the standard anticoagulant used in atrial fibrillation. Using Coumadin safely and effectively requires weeks or months of frequent blood tests and dosage adjustments. And even with these efforts, the "correct" dosage of Coumadin can vary from time to time in any individual -- and so there is always the risk that a patient taking Coumadin may not be getting enough of the medication (thus increasing the risk of stroke) or may be getting too much (thus increasing the risk of bleeding events).
Dabigatran, on the other hand, appears to give just the right amount of anticoagulation on a standard dose, and therefore requires no blood testing or dosage adjustments.
However, all anticoagulant drugs "thin the blood" -- that is, they reduce blood clotting. This means that bleeding is a potential risk inherent with any of these drugs. Sometimes, bleeding problems can become serious, or even life-threatening.
When a bleeding problem occurs while a person is taking Coumadin, a blood test is readily available to measure the "thinness" of the blood, and a treatment is available (administering large doses of vitamin K) to reverse the effect of Coumadin. So the bleeding can usually be controlled relatively quickly.
This is not the case with dabigatran. With readily available blood tests, the "thinness" of the blood can only be estimated - and not measured precisely - in patients taking dabigatran. And there is no way to quickly reverse the effects of the drug.
Here is what UpToDate, an electronic reference for doctors and patients, has to say about treating bleeding events that occur on dabigatran:
"There is no specific antidote for dabigatran. Suggestions for reversing its anticoagulant effect have included the following:
- Drug discontinuation is usually sufficient to control bleeding in most clinical settings, since its half-life is relatively short (12 to 14 hours) in subjects with normal renal function.
- Dabigatran is about one-third protein bound. It can be dialyzed in patients with renal impairment, with about 60 percent being removed after two to three hours of dialysis; charcoal hemofiltration has been suggested.
- Other drugs that may potentiate bleeding should be discontinued, if possible.
- Use of activated charcoal may remove unabsorbed drug from the gastrointestinal tract.
- Where there is life-threatening bleeding, the use of prothrombin complex concentrates (PCC) has been suggested, although in one study in 12 normal volunteers the use of PCC did not reverse dabigatran-associated prolongations in the aPTT, ecarin clotting time, or thrombin time."
In other words, at this point, there is no way to quickly reverse the anticoagulation effect of dabigatran, should a bleeding problem occur. Doctors can prevent recently-taken dabigatran from being absorbed from the gut (with activated charcoal). They can try administering PCC (Beriplex, a combination of blood clotting factors that is given intravenously), but this drug does not appear particularly helpful with dabigatran. Or, dialysis can be tried, in people with kidney disease.
But essentially, the treatment is to support the patient as best one can, and wait for the effect of dabigatran to dissipate -- which will take 12-24 hours following the last dose. If the bleeding is life-threatening, this may not be an attractive choice.
Recently, the Food and Drug Administration published a Safety Alert regarding the difficulty in treating bleeding problems with dabigatran. The purpose of this communication was simply to call the attention of physicians and patients to the issue, and to say that the agency will monitor the problem carefully to judge the magnitude of the problem.
A new drug has been developed to reverse dagibatran's anticoagulant activity, but unfortunately this drug is in the early stages of clinical testing and is not yet available.
What You Need To Know
If you have atrial fibrillation, your risk of stroke is likely to be substantially elevated. Taking an anticoagulation medication -- despite the risks of therapy -- has been shown to substantially and significantly reduce the risk of stroke in people with atrial fibrillation.From the information available today, taking dabigatran is at least as safe and at least as effective as taking Coumadin -- and it is far more convenient. What you need to take into account, however, is that if a bleeding problem should occur while you are taking dabigatran, it may be more difficult for your doctor to treat the problem than it would be if you were taking Coumadin.
Taking any anticoagulant medication is a serious matter. You should discuss your need for an anticoagulant -- and which anticoagulant is better for you -- with your own doctor.
Want to learn more? See UpToDate's topic, "Information On Anticoagulants," for additional in-depth medical information.
Sources:
Leung LLK, Mannucci PM. Anticoagulants other than heparin and warfarin. UpToDate. Accessed: February, 2012.
