Heart Health
The best anti-clotting drug for afib?
Ask the doctor
Q. I have atrial fibrillation and take Xarelto. But I heard about a study that suggests Eliquis is more effective for preventing strokes in people with atrial fibrillation. I'm wondering if I should switch. Your thoughts?
A. Both of these anti-clotting medications, rivaroxaban (Xarelto) and apixaban (Eliquis), are FDA-approved for preventing strokes in people with atrial fibrillation (afib). They both belong to a class of drugs known as direct oral anticoagulants, or DOACs. They work by inhibiting a substance called factor Xa, which plays a key role in blood clot formation. And both drugs have a half-life of about eight hours, which means that the blood level of the drug drops by half over an eight-hour period. But there are some differences between the two.
The standard dose of rivaroxaban for preventing strokes due to afib is a 20-milligram (mg) pill once a day. After you take the pill, blood levels are high over the following hours, but the level drops by half within eight hours. As a result, there's a large difference in the peak level versus the lowest level. In contrast, most people take apixaban as a 5-mg pill twice a day. Compared to rivaroxaban, the peak blood levels are not as high, and the lower level is not as low.
High levels of an anti-clotting drug can lead to bleeding, while lower levels may increase the risk of blood clot formation. As such, it makes sense that the twice-a-day dosing would have a lower risk of bleeding and potentially better clot prevention.
The study you're referring to, which looked at health records of more than 580,000 people who were prescribed either drug, supported that assumption: people taking apixaban experienced lower rates of both bleeding and clotting events. However, this was an observational trial, which means there may have been many differences between the people who were given one drug versus the other, and those differences could explain the results. Only a blinded, randomized clinical trial that controls for those possible differences can provide a more definitive answer.
There is no clinical trial comparing rivaroxaban to apixaban. But both drugs have been pitted against warfarin (Coumadin), an older medication that was the mainstay for clot prevention before DOACs were approved. The findings seem to support the trend shown by the large observational trial; that is, apixaban compared to warfarin had lower rates of bleeding, stroke, and death, whereas rivaroxaban had no significant difference on these events compared to warfarin. With only these indirect comparisons, however, we can't say for sure that apixaban is better than rivaroxaban.
The downside to apixaban is that you have to take it twice a day. People who are likely to forget their second dose may be better off taking rivaroxaban. Talk to your doctor about whether it makes sense for you to switch.
Image: © Artur Plawgo / Science Photo Library/Getty Images
About the Author
Christopher P. Cannon, MD, Editor in Chief, Harvard Heart Letter; Editorial Advisory Board Member, Harvard Health Publishing
Disclaimer:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.