FDA has approved four new blood thinners in recent years — Dabigatran (Pradaxa), Rivaroxaban (Xarelto), Apixaban (Eliquis), and Edoxaban (Savaysa). Along with Warfarin, a drug approved 60 years ago, these drugs are used to prevent stroke in patients with atrial fibrillation.

There are some important differences among these drugs. Warfarin interacts with certain drugs and foods that make it less effective or more likely to cause bleeding in these settings. That is why its effects must be monitored with periodic blood tests. The new drugs have fewer interactions and don’t require blood test monitoring.

Although all anticoagulants reduce the risk of a stroke caused by clots from the heart, they increase the risk of a stroke caused by bleeding into the brain (a hemorrhagic stroke). The newer drugs cause fewer bleeding strokes than warfarin, and the overall rates of strokes (caused by blood clots or bleeding) are lower with the newer drugs.

Another difference is based on the mode of action of these drugs, i.e how fast the drugs start and stop working. When starting warfarin, it takes a few days before the drug takes effect, and when stopping warfarin, it takes a few days for its effects to wear off.

The new drugs start working much faster, and their effects wear off rapidly. For most patients, this is an advantage, especially when having non-cardiac procedures or surgery. On the other hand, on rare instances arely, when patients have life-threatening bleeding or need urgent surgery, it can be important to stop the effects of these drugs immediately.

For the rare patient with life-threatening bleeding, reversal agents can be used to counter the effects of anticoagulants. For example, Vitamin K is the reversal agent for warfarin. The FDA recently approved the first antidote agent for Pradaxa (Praxbind or Idrucizumab). Praxbind is licensed for use in emergency situations when bleeding caused by Pradaxa’s blood thinning effects cannot be controlled.