Warfarin vs. Pradaxa and the Other New Anticoagulants
by Steve S. Ryan, PhD, Update July 2014, June 2015, October 2015
“I’ve read about people bleeding to death in the ER because they are on the new anticoagulant Pradaxa. Doctors can’t stop the bleeding, even from minor cuts. Is that true? Doesn’t Coumadin carry the same risk? What about the other new anticoagulants Xarelto and Eliquis?”
You’re correct about Pradaxa and the reported bleeding deaths (See “Stop Prescribing or Taking Pradaxa: Suspect in 542 deaths.”) None of the new anticoagulants (including Xarelto and Eliquis) has a proven, reliable antidote or reversal mechanism. But, Pradaxa, in particular, has been associated with tragic deaths in the ER where doctors are helpless and can only watch as someone bleeds to death.
Most would agree that the worst thing that can happen to a patient with A-Fib is a life-altering stroke. A stroke often causes death or permanent disability. Thus the importance of anticoagulation therapy for A-Fib patients.
For many years, there was only one proven therapy for stroke prevention in A-Fib patients at high or intermediate risk for stroke: the anticoagulant Coumadin (warfarin). It’s readily available and inexpensive.
But maintaining correct Coumadin levels is difficult especially over the long haul (studies indicate around 30% of people will stop taking Coumadin).
But maintaining correct Coumadin levels is difficult especially over the long haul (studies indicate around 30% of people will stop taking it).
In addition, Coumadin taken over several years may lead in microbleeds in the brain and dementia. (Read about the post-ablation patient on anticoagulation therapy for 10 years who develops cerebral microbleeds and early dementia: The New CHA2DS2-VASc Guidelines and the Risks of Life-Long Anticoagulation Therapy )
For patients at low or intermediate risk of stroke (including younger patients without any additional stroke risk factors) aspirin may be prescribed, or no anticoagulation therapy at all.
Read about the post-ablation patient on anticoagulation therapy for 10 years who develops cerebral microbleeds and early dementia: The New CHA2DS2-VASc Guidelines and the Risks of Life-Long Anticoagulation Therapy
The NOACs Trials
For over 20 years there have been extensive efforts to replace warfarin with other drugs. In the US, we have four new anticoagulants to consider: Pradaxa (dabigatran), Xarelto (rivaroxaban), Eliquis (apixaban), (added January, 2015) and the recently approved (January, 2015) Savaysa (edoxaban)).
The data on the new anticoagulant come from three randomized controlled trials involving more than 50,000 A-Fib patients:
Each study compared one drug against warfarin (not against each other). Taken together, these studies consistently revealed that A-Fib patients who took the non-warfarin blood thinners suffered fewer strokes, intracranial bleeds, and serious bleeds than those who took warfarin.
All of these drugs are at least as good as warfarin for preventing stroke and all are better than warfarin in reducing your risk of serious bleeding in the brain. But none have antidotes or reversal agents (at this time).
Note: Each of these NOAC trials had a questionable bias toward the new drug when compared against warfarin. Warfarin users are notoriously non-compliant, up to 50% are inconsistent in managing their diet, monitoring their INR levels and taking the correct dosage.4 Each of the three trials compared a group of compliant patients against a group of inconsistent warfarin patients. So results should be viewed with a critical eye.
For a more in-depth look at the clinical trials of the new NOACs, see 2013 BAFS: The New Anticoagulants (NOACs).
Three Notable Concerns
The new anticoagulants offer several advantages over warfarin. They are fast acting. And when stopped (i.e., for surgery), they just as quickly clear your body (a short “half-life). There’s a broad therapeutic window (wide range of safe use), and they have minimal drug or dietary interactions. They can be administered in fixed doses without monitoring, making them potentially more convenient to use than warfarin.
Remember: The goal of anticoagulation therapy is to reduce your risk of life-altering stroke.
Enthusiasm for the new anticoagulants, (NOACs), however, must be tempered by three notable concerns in patients taking these drugs:
1. No readily available means for assessing the degree of anticoagulation
2. No readily available reversal strategy
3. Life-threatening bleeding complications can occur after an injury
(Added May, 2015) Dr. Stephen Kimmel of the Un. of Pennsylvania discusses a fourth concern—stomach problems and gastrointestinal bleeding. “If you have a history of stomach problems or gastrointestinal bleeding, you may want to avoid Pradaxa and Xarelto—both medications have the highest risk for those complications.”5
No Way to Measure Effectiveness
One of the problems with the newer anticoagulants (NOACs) is we don’t have a good way to measure how effective they are or how much of an anti-clotting effect there is at a given point in time. (For example, in treating trauma patients, ER doctors can only use the elapsed time from the last dose to estimate the clotting effect.)
With Coumadin (warfarin), on the other hand, we can measure how effective it is by its level in the blood stream measured in INR (International Normalized Ratio). A person not on anticoagulants will have an INR slightly above 1 (the author’s INR is 1.1). Someone with A-Fib on Coumadin should have an INR between 2.0 and 3.0. At this INR level a person will bleed more than someone with an INR of 1.0, but the blood will still clot.
With an INR below 2.0 you are more in danger of having an ischemic (clotting) stroke, the kind that most often occurs in A-Fib. With an INR of 4.0 and above, there is much more risk of blood not clotting and of developing a hemorrhagic stroke.
But the INR blood test doesn’t work with the new anticoagulants which affects only one particular stage in the anticoagulation process. Pradaxa, for example, is a direct thrombin inhibitor, whereas Coumadin affects nearly every stage in the anticoagulation process. (Thrombin is an enzyme that converts soluble fibrinogen into insoluble fibrin. Fibrin is a fibrous protein involved in the clotting of blood. It forms a mesh or clot over a wound.)
The lack of a readily available method to determine the degree or current level of anticoagulation is a major challenge for ER physicians and staff treating trauma patients.
Are the NOACs Too Effective?
Pradaxa, in particular seems to work almost too well.
Pradaxa, in particular seems to work almost too well.
Coumadin on the other hand has several proven, time-tested reversal or antidote strategies.6
Pradaxa (dabigatran) won the FDA sweepstakes by being the first new anticoagulant to get FDA approval and consequently captured a significant share of the anticoagulant market. Pradaxa comes in two doses in the United States, 150 mg twice daily or 75 mg twice daily. It’s large and harder to swallow, comes in a bottle with a 30-day shelf life once opened (or in blister packs which eliminates the shelf-life problem.) And it’s expensive.7 In the RELY trial, Pradaxa was not only equal to warfarin, but it proved to be superior to it in preventing stroke. Bleeding rates in the head were lower with Coumadin. However, bleeding from the stomach or bowels was higher. The most common side effect was stomach pain.
In addition to the bleeding deaths in the ER mentioned above, Pradaxa’s own fact sheet states common side effects of Pradaxa include:8
• Indigestion, Upset Stomach, or Burning
• Stomach Pain
[These statements don’t capture the actual human toll—burning throat, roiling intestines, diarrhea, burning anus, lasting intestinal damage, etc. that Pradaxa can produce in some people.]
Xarelto and Eliquis Test Better
Xarelto (rivaroxaban) was the second drug available in the United States. Xarelto comes in two doses, 20 mg daily or 15 mg daily. In contrast to Pradaxa, it is a small pill taken once-a-day that doesn’t seem to cause a lot of intestinal problems. In the Rocket AF trial, Xarelto also significantly lowered the risk of bleeding in the brain and head compared to Coumadin. Like the other new anticoagulants, Xarelto also doesn’t have a reversal agent; but anecdotally we don’t seem to see a lot of deaths in the ER from Xarelto.
Eliquis (apixaban) was third to be approved, comes in two doses, 5 mg twice daily or 2.5 mg twice daily (the lower for A-Fib patients with kidney dysfunction). Similar to Xarelto, the risk of bleeding in the brain and head was lower versus Coumadin. However, this drug was unique in that bleeding from other sites including the stomach, bowels, and bladder was less. In the Aristotle trial, Eliquis was at least as good and tended to be better than warfarin at preventing stroke. Eliquis is the only drug that can claim that survival improved with its use compared to warfarin.
Xarelto and Eliquis, just like Pradaxa, are also very expensive.
The reported bleeding events tend to occur mainly in elderly patients (median age of 80) which raises a question regarding safe dosing and monitoring in older patients. Elderly patients often have mild to moderate renal impairment, which can cause plasma levels of the NOAC to increase to up to three times those in normal renal function.
“One-size-fits-all” dosage of these new anticoagulants may need to be re-examined for elderly patients. (The FDA rejected the lower 110-mg twice-daily dose of Pradaxa (dabigatran) tested in the RE-LY trial, instead approving a 75-mg twice-daily dose just for patients with severe renal impairment.)
Lack of a proven, reliable antidote or reversal mechanism creates a major challenge for trauma staff.
With a relatively short elimination half-life, for now, time may be the most important antidote for NOACs.
Eliquis Earns Best Safety Score
Through an analysis of data from the FDA Adverse Event Reporting System by AdverseEvents, Inc., Eliquis has received an “RxScore” safety score of 39.45 on a 100 point scale, with 100 representing the highest risk. In comparison, warfarin had a score of 67.57. Pradaxa (dabigatran) had a score of 67.15, Xarelto (rivaroxaban) 67.08.9,10
The FDA’s database comprises all the reports made by doctors, patients and other healthcare providers, which means it’s not a “scientific” finding with the authority of a clinical trial. AdverseEvents applies logic, math and software to the database to sift out the important data.
For Eliquis, “the rate of suspect cases was lower in every type of adverse-event report, from hospitalization to death.” For example, among Eliquis patients reporting side effects, only 21% cited hospitalization, while Pradaxa had 39%, Xarelto 43% and warfarin 50%.
The results all point to the same general conclusion: Eliquis may be a safer choice among the new NOACs.
Update May 2014: Pradaxa
Since it was approved for use in 2010, Pradaxa has been linked to more than 500 patient deaths. More than 1,600 individuals have filed lawsuits in state and federal courts in the United States alleging they suffered bleeding events caused by the drug.
In May 2014, Boehringer-Ingelheim, the privately held German company that makes Pradaxa, settled 4,000 Pradaxa lawsuits and will pay $650 million. The lawsuit states that Pradaxa can cause bleeding events that cannot be controlled and are sometimes fatal.11
Pradaxa has generated $1 Billion in revenue for Boehringer-Ingelheim. So, will this $650 million settlement hurt BI’s bottom line and affect its marketing of Pradaxa? (BI’s revenues in 2012 were $1.5 billion). Probably not.
If you’re conscientious and are pretty good at staying in the proper INR range, stick with Coumadin if you can. It may not be as convenient and easy to use as the newer anticoagulants, but we know Coumadin works if you stay within the proper INR range. And there are proven reversal agents for Coumadin, unlike for the newer anticoagulants. The cost of Coumadin is significantly lower when compared to the new anticoagulants.12
Update June 2015: Instead of the above statement, I suggest you talk with your doctor about switching from warfarin (Coumadin) to the NOAC Eliquis (apixaban). Studies show that warfarin produces arterial calcification and plaque which damage your heart over time. (See Stop Taking Warfarin! Switch to Eliquis.) Eliquis doesn’t block Vitamin K like warfarin, it tested better than the other NOACs and is safer.
If you struggle with staying in the proper INR range13, can’t juggle the diet restrictions or monthly monitoring, you should talk with your doctor about switching to Eliquis. It has no interactions with food (not even spinach) and requires NO monitoring (no more finger stick checks). Though be aware of Eliquis’ much higher monthly price.14 You will need to judge if the benefits outweigh the costs.
When choosing an anticoagulant, you need to consider which is worse: the risk of uncontrolled bleeding or the risk of a debilitating stroke.
Update October 26, 2015: FDA Approves Reversal Agent for Pradaxa (dabigatran)
In a new study of 90 patients who had uncontrolled bleeding with Pradaxa, Praxbind (idarucizumad) stopped this bleeding within minutes. No serious side effects were reported.
We have previously reported on the reversal agent Andexanet Alfa which is on FDA fast track approval as an antidote to the Factor Xa inhibitors Xarelto and Eliquis. FDA approval is pending.15,16
Last updated: Saturday, March 26, 2016
- Connolly SJ, et al. RE-LY Steering Committee and Investigators. Dabigatran versus warfarin in patients with atrial fibrillation. N Engl J Med. 2009;361(12):1139-51. Last accessed July 10, 2014 URL: http://www.ncbi.nlm.nih.gov/pubmed/19717844↵
- Patel MR, et al. ROCKET AF Investigators. Rivaroxaban versus warfarin in nonvalvular atrial fibrillation. N Engl J Med. 2011;365(10):883-91. Last accessed July 10, 2014, http://www.ncbi.nlm.nih.gov/pubmed/2183095↵
- Granger CB, et al. ARISTOTLE Committees and Investigators. Apixaban versus warfarin in patients with atrial fibrillation. N Engl J Med. 2011; 365(11):981-92 Last accessed July 10, 2014↵
- Ansell J, et al. Descriptive analysis of the process and quality of oral anticoagulation management in real-life practice in patients with chronic non-valvular atrial fibrillation: the interactional study of anticoagulation management (ISAM) J Thromb Thrombolysis 2007; 23: 83—91. Last accessed July 10, 2014↵
- Kimmel, Stephen. The Truth About Blood Thinners, Bottom Line/Health, May 2015, p. 11↵
- Coumadin reversal or antidote strategies: Vitamin K antagonist, Fresh Frozen Plasma, Prothrombin Complex Concentrate (PCC), and the newly FDA-approved Kcentra.↵
- Pradaxa costs about $250 a month; By comparison, warfarin (Coumadin) costs about $60-$80/month when you add in INR monitoring once a month. Last accessed July 10, 2014↵
- Pradaxa: Highlights of Prescribing Information. Boehringer-Ingelheim website. Last accessed March 13, 2014 URL: http://tinyurl.com/PraxadaInfo↵
- Examining the Comparative Safety of Blood Thinners: An Analysis Utilizing AdverseEvents Explorer, February 2014, Special Report Download. http://info.adverseevents.com/special-report-blood-thinner Last accessed July 10, 2014↵
- Staton, Tracy. Eliquis earns best safety score in its class in analysis of FDA adverse event reports. FiercePharma, February 26, 2014. Last accessed July 10, 2014, http://www.fiercepharma.com/story/eliquis-earns-best-safety-score-its-class-analysis-fda-adverse-event-report/2014-02-26↵
- Feeley, Jef. Boehringer Pays $650 Million to End Blood-Thinner Cases. May 28, 2014. Bloomberg.com. Last accessed July 10, 2014, URL: http://www.bloomberg.com/news/2014-05-28/boehringer-pays-650-million-to-end-blood-thinner-cases.html↵
- Your insurance provider will have a direct say into which drug you take.↵
- Consider a warfarin sensitivity test. About a third of the people who take warfarin are at a higher risk of bleeding because their genes make them more sensitive to warfarin. If a family member experienced side effects, talk to your doctor about taking a genetic warfarin sensitivity test.↵
- For those in the US and on Medicare with Part D coverage, the monthly cost may range from $30 to $50.↵
- Marzo, Kevin. Blood thinner Antidote. Bottom Line Health, Volume 29, Number 9, September 2015, p. 1.↵
- Mundell, E.J.. Drug May Be Antidote to Bleeding Tied to Blood Thinner Pradaxa. Medline Plus. Monday, June 22, 2015. http://www.nlm.nih.gov/medlineplus/news/fullstory_153206.html↵