When deciding what type of blood thinner is best, the question of Eliquis versus Warfarin often arises. Blood thinners, also called anticoagulants, are a class of medications that “thin” or prolong the time it takes for your blood to form a blood clot. Simply put, blood thinners stop blood clots. The usefulness of blood thinners comes from their power to prevent blood clots and reduce or eliminate blood clots that have already formed in your veins, arteries, or organs. This ability makes blood thinners an important class of medications for the treatment, prevention, or management of a variety of medical conditions including, but not limited to:
- Stroke in atrial fibrillation (AFib)
- Deep vein thrombosis (DVT)
- Pulmonary thromboembolism (PTE)
- Acute myocardial infarction (AMI or “heart attack”)
- Heart valve surgeries and certain heart valves
- Certain congenital heart defects
- Genetic or acquired hypercoagulable states
There are a variety of blood thinners, some of the major types include: vitamin K antagonists (coumarins), heparin or low molecular weight heparin (LMWH), direct thrombin inhibitors, and factor Xa inhibitors. For decades, the blood thinners of choice were Coumadin (warfarin) and heparin. Recently, however, several other medications known as novel oral anticoagulants (NOACs) are readily available. The available NOACs include: Pradaxa (dabigatran), Xarelto (rivaroxaban), Eliquis (apixaban), and Savaysa (edoxaban). The NOACs have been evaluated for the prevention of stroke in AFib and treatment and prevention of DVTs and PTEs. In this post we will compare and contrast Eliquis (apixaban) and Coumadin (warfarin).
What is Coumadin (warfarin)?
Warfarin has been safely used around the world for decades. Warfarin treats and prevents blood clots by decreasing the production of several vitamin K-dependent blood clotting proteins, hence the name vitamin K antagonist. Warfarin requires frequent laboratory monitoring and dose adjustment to maintain warfarin levels within a small therapeutic window, as measured by an international normalized ratio (INR) blood test. The INR range is determined by a physician and is specific for the particular medical indication. For most patients, the INR range is 2 to 3. This small therapeutic window can be very difficult to achieve in some patients. It takes about 5-10 days for the blood thinning effect of warfarin to begin and to wear off, so it must be stopped several days before any medical procedure or surgery. During breaks in warfarin treatment, patients may need to “bridge” themselves with other blood thinners to prevent blood clots until the warfarin levels slowly get back into therapeutic range. Most importantly for patients, certain foods that contain vitamin K (e.g. green leafy vegetables, spinach, brussel sprouts, kale, etc.) and certain medications (e.g. antibiotics, blood pressure medications, cholesterol medications, herbal supplements, etc.) can decrease or increase warfarin levels. These food and medication interactions make managing a patient’s warfarin level even more difficult. Warfarin is inexpensive relative to other blood thinning options and a month’s supply can cost $4.00 at almost all pharmacies. The NOACs are indeed more expensive than warfarin and the prices can vary depending on your health insurance coverage. However, the NOACs have been clearly shown to be cost-effective alternatives to warfarin. This is even truer with regards to Eliquis, when compared to the other NOACs, according to the United Kingdom National Health Services (NHS).
What is Eliquis (apixaban)?
Eliquis is a factor Xa inhibitor, all NOACs inhibit individual clotting proteins, thus inhibiting coagulation and making the blood thin. The ARISTOTLE trial showed that treatment with Eliquis prevented more strokes, caused less bleeding, and had an 11% reduction in death compared to warfarin. This “triple” advantage in AFib is true only for Eliquis; no other NOAC can make that statement. The 11% reduction in death was primarily from a reduction in cardiovascular death, particularly stroke deaths, because nonvascular death rates were similar to warfarin. Eliquis is similarly effective in comparison with warfarin for the treatment and long-term prevention of DVT and PTE, but has fewer major bleeding complications. Of note, no NOAC should be used for blood thinning in patients with mechanical heart valves. Warfarin or heparin/LMWH are the only blood thinners that should be used in patients with mechanical heart valves. Overall, there is convincing evidence that Eliquis is consistently superior to warfarin and it is increasingly difficult to view Eliquis simply as an alternative to warfarin.
Eliquis has minimal interaction with foods and other medications, thus there are no dietary restrictions. Eliquis does not require laboratory monitoring or dose adjustment. However, the prothrombin time (PT) or anti-Xa activity can provide a qualitative measurement of the presence of factor Xa inhibitors. Eliquis is shorter-acting than warfarin and the blood thinning effect is quickly gained or lost after about 24 hours. Eliquis rarely requires bridging because it is shorter-acting and can be safely stopped a day or two before any medical procedure or surgery. A major criticism of the NOACs concluded that there was no way to “reverse” the blood thinning effect in patients who were actively bleeding. That particular limitation for Eliquis has now recently changed. Andexanet alfa was designed to reverse the blood thinning effects of factor Xa inhibitors. Recently, the first randomized control trial showed that andexanet alfa reversed the bleeding effects of Eliquis safely and effectively without any evidence of major side effects. Additionally in the future, four-factor prothrombin complex concentrate (4F-PCC or Kcentra) may have potential for reversing the bleeding effects of Eliquis in cases of acute bleeding or prior to emergency surgery.
Eliquis versus Warfarin: Which is the Best Blood Thinner for You?
It should be noted that there are no direct study comparisons between the different NOACs to date. However, for patients at risk for stroke in AFib, Eliquis is the only NOAC that is better than warfarin in the prevention of stroke and results in fewer bleeding complications. Based on the current available evidence it appears that, among the different NOACs, Eliquis has the most favorable risk-to-benefit ratio compared to warfarin. The favorable benefits of Eliquis compared to the other NOACs likely extends to the other indications for blood thinners as well, including DVT and PTE, but this has not yet been proven by any clinical studies.
So what is the verdict for Eliquis versus Warfarin? Eliquis is a very attractive alternative to warfarin, and even to the other NOACs, because of the improved effectiveness and enhanced safety profile for its FDA approved indications. However, the best blood thinner for you and your specific indication should be decided after a thoughtful physician-patient discussion.