New Blood Thinners Make Life Easier for Many
Here's what you need to know about alternatives to warfarin.
If you have atrial fibrillation, your doctor has probably prescribed warfarin (Coumadin ®) to help prevent a blood clot from forming in your heart. But if you are frustrated by efforts to maintain proper blood levels of warfarin, or have experienced complications from the medication, switching to a novel oral anticoagulant (NOAC) may make your life easier.
“NOACs have been intensely studied in patients with nonvalvular atrial fibrillation. Even in very high-risk patients, they have been shown to be as safe as, or safer than, warfarin for preventing strokes,” says Cleveland Clinic electrophysiologist Thomas Dresing, MD.
This is good news, indeed, especially because women with atrial fibrillation tend to be particularly vulnerable to stroke and complications from warfarin.
What NOACs are
For 50 years, warfarin was the only blood thinner on the market. Because it has been used for so long, physicians are familiar with its properties and quirks and know how to use it in all types of patients.
In the mid- to late-2000s, other compounds that safely and effectively intervened in the development of blood clots were identified and tested in clinical trials. Three NOACs have since been FDA-approved for use in patients with atrial fibrillation not caused by a heart-valve problem: Factor Xa (pronounced like 10a) inhibitors rivaroxaban (Xarelto ®) and apixaban (Eliquis ®), and the direct thrombin inhibitor dabigatran (Pradaxa ®). The two classes of NOACs differ from warfarin and each other by interfering with the process of clot formation in different ways. Yet all achieve the same goal.
Advantages of NOACs
NOACs have many advantages over warfarin:
- NOACs thin the blood immediately. Achieving the desired level of anticoagulation with warfarin can take five to 10 days, or longer.
- NOACs do not interact with foods. Patients taking warfarin must limit intake of foods with vitamin K, such as green leafy vegetables.
- NOACs interfere with fewer medications than warfarin.
- NOACs provide a consistent level of anticoagulation. Blood levels of warfarin vary widely, so that 20 to 40 percent of patients have levels that are too high or too low.
- NOACs are less likely to cause hemorrhagic stroke than warfarin.
- NOACs have been shown to reduce the risk of death. Warfarin does not have this overarching benefit.
Great, but not perfect
While these advantages make NOACs preferable over warfarin, the new drugs are not ideal for everyone, including patients with compromised kidney function. Because kidney function declines with age, doses have to be adjusted accordingly. People with severe kidney disease and those on dialysis cannot use NOACs.
NOACs may cause internal bleeding, so they are not appropriate for anyone with a history of ulcers or other bleeding disorder. However, some NOACs appear to be safer than others, which gives physicians some flexibility. “If a patient suffers from bleeding with one NOAC, I usually switch to another,” says Dr. Dresing.
Potential complications aside, some patients simply can’t afford the new drugs. “They come with a higher price tag, which may mean higher out-of-pocket costs,” says Dr. Dresing. Some insurance carriers, including Medicare, won’t pay for NOACs until the patient has failed a trial of warfarin.
But overall, NOACs have won over many physicians. “No blood thinner has zero risk. But when compared to Coumadin, NOACs provide as good or better protection against stroke,” says Dr. Dresing.
“If I’m starting a patient on blood-thinners, I steer them to NOACs. But if they’ve been well-maintained on Coumadin, I usually don’t recommend switching.”