Boehringer Ingelheim won FDA approval for blood thinner Pradaxa (dabigatran) to prevent stroke in patients with atrial fibrillation (AFib). The twice-daily, oral med, which doesn't require anticoagulation monitoring like warfarin, could capture a sizable portion of the decades-old blood thinner's market. Boehringer Ingelheim, set to launch Pradaxa within days, is reaching the US market ahead of rivals Johnson & Johnson and Bayer, which filed an NDA for their own warfarin replacement, oral anticoagulant Xarelto (rivaroxiban), in 2008, and before Bristol-Myers Squibb and Pfizer, whose apixaban is in Phase III. J&J and Bayer received a complete response letter in 2009 requesting more clinical data on Xarelto, and FDA has yet to hand down a decision. The warfarin replacement market is so big, analysts estimate, that all three drugs should exceed $1 billion in US sales should they be approved. Pradaxa and Xarelto are already approved in other territories, including several countries of the EU.