by Kali Schweitzer, PharmD candidate 2018
University of Arizona College of Pharmacy
Not so long ago, a diagnosis of atrial fibrillation (AFib), deep vein thrombosis (DVT), or pulmonary embolism (PE) meant that a prescription for the blood thinner, warfarin (Coumadin), was likely coming your way. In recent years, multiple other blood thinners have become available, and you may have wondered if any of them could be right for you.
What are NOACs?
The NOACs, or novel oral anticoagulants, are a new breed of blood thinner that have arrived on the market within the last ten years. This class of medications includes:
How are NOACs Different from Warfarin?
Multiple clinical trials comparing these alternative warfarin medications have all shown that the NOACs are just as effective as warfarin, and that they have a similar (or lower) risk of bleeding. Warfarin has been around for decades and has been proven to be both safe and effective at preventing blood clots, but it’s no secret that it has its problems. Here are some key differences to note when comparing the newer anticoagulants with warfarin and when deciding what is right for you:
- Warfarin requires frequent trips to the lab to have your INR (international normalized ratio) checked. Also referred to as PT time, Prothrombin time is a blood test that measures how long it takes blood to clot, or how well the medication is working. You may potentially need to change your dose to increase or decrease the clotting time. NOACs do not require lab monitoring or frequent dose changes.
- NOACs do not have the high potential to interact with food or other medications like warfarin does, meaning there are fewer restrictions. This means no more worrying about how much salad you can eat on a day-to-day basis, or if you are allowed to have that glass of grapefruit juice in the morning. It is still recommended, however, to check with your doctor or pharmacist before starting any new medications, as there are still some medications that may increase your risk of bleeding when taken with the NOACs.
- NOACs begin working quickly, while warfarin may take up to a week to start working. Because of this, patients with a DVT or PE starting warfarin may require “bridge” therapy with heparin or enoxaparin (other fast acting blood thinners) to prevent clots while waiting for the warfarin to take effect. This “bridge” therapy is not necessary with the NOACs.
- Unlike warfarin, not all of the NOACs have a reliable reversal agent if you were to begin bleeding. With warfarin, if your INR becomes too high or if you are having signs of bleeding, you may be given vitamin K, or phytonadione, to reverse its effects. Currently, Pradaxa is the only NOAC that has an approved reversal agent, called Praxbind (idarucizumab). While bleeding is rare while on the NOACs, the lack of reversal agent is something to keep in mind when deciding which medication may be right for you.
- NOACs may not be appropriate if you have decreased kidney and/or liver function. Your doctor will review your labs and information to determine if your kidneys/liver are functioning well enough for you to take one of these medications.
The recent approval of the NOACs has provided prescribers and patients with more options to choose from when a blood thinner is necessary. Because these medications are still relatively new, there is a lot left to learn about their use and limitations, so they may not be appropriate for everyone. It is always important to discuss any questions or concerns with your doctor when starting any of these medications or when switching from one to another.
Leung LLK, Direct oral anticoagulants and parenteral direct thrombin inhibitors: Dosing and adverse effects. In: UpToDate, Mannucci PM (Ed.), UpToDate, Waltham, MA.
Hanley CM, Kowey PR. Are the novel anticoagulants better than warfarin for patients with atrial fibrillation? Journal of Thoracic Disease. 2015;7(2):165-171. doi:10.3978/j.issn.2072-1439.2015.01.23.