Long-term side effects of Pradaxa are as yet unknown
BY DR. KOMOROFF Universal Uclick
Tuesday, February 19, 2013
2/19/13 at 3:44 AM
Dear Doctor K: My wife has atrial fibrillation. Her medication was recently changed from warfarin to Pradaxa. Her doctor says the new medicine does not require regular INR tests and is just as effective. Is that so?
Dear Reader: Yes, it is.
Warfarin is an important anticoagulant medicine, but the dosing is tricky. If the dose is too low, clots form. If it's too high, bleeding problems may result. The international normalized ratio (INR) is a blood test. Anyone on warfarin must have regular INR tests to ensure their dose is correct.
Pradaxa appears to be just as effective as warfarin at preventing blood clots. It is probably more effective at preventing strokes and probably causes fewer cases of bleeding in the brain (a side effect of any anticoagulant). What's more, its effect on the blood is more predictable than warfarin's. As a result, regular INR tests aren't necessary. That's a big advantage.
There are, however, two risks to Pradaxa. First, the drug has a short half-life: It is largely out of your system in less than 24 hours. If you miss a dose, you have an increased risk of developing a blood clot compared to if you missed a dose of warfarin.
The second risk is that treatments to rapidly reverse the effects of Pradaxa are unproven. It's easy to reverse the effects of warfarin. If you were injured and started bleeding profusely, for example, you'd want to quickly reverse the anti-clotting effects of the drug.
Another issue with Pradaxa is expense. And because it's new, we don't have good information on any possible long-term side effects.
Anticoagulant drugs that don't require regular blood tests are quite attractive. Not surprisingly, there are several in the pipeline. Rivaroxaban (Xarelto) is approved in the United States to prevent blood clots in the legs and in people having certain types of surgery of the legs. It has not yet been approved for atrial fibrillation.
Write Dr. K at www.AskDoctorK.com or c/o Universal Uclick, 1130 Walnut, Kansas City, MO 64106
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