The search for an alternative to the pain-in-the-### that is warfarin goes on. There are some promising candidates. The FDA approved dabigatran (Pradaxa™), a direct thrombin inhibitor, back in November of last year. It has its pros and cons. In short, it is more effective than warfarin in preventing stroke in patients with non-valvular atrial fibrillation and is 74% less likely to cause serious bleeding than warfarin. No monitoring needed, either. Rivaroxaban(Xarelto™) is hot on its heels. Yesterday, as reported on theheart.org, Bristol-Myers Squibb reported that their new entry into the anti-coagulant quagmire, apixaban (Eliquis™), a factor Xa inhibitor, is “noninferior” to warfarin in preventing stroke in atrial fibrillation.
This is just a preliminary report and there is no real data to look at right now. If you happen to be in Paris (yes, France) on August 28th, you can catch a detailed report at the European society of Cardiology Congress. The press release goes on to report that not only is apixaban noninferior to warfarin, it is also superior to warfarin in both stroke prevention and bleeding risk. Noninferiority and superiority aren’t the same thing, apparently, and it’s kind of a big deal, or so it appears.
The ARISTOTLE trial (Apixaban for the Prevention of Stroke in Subjects with Atrial Fibrillation) – where do you get ARISTOTLE out of that? – enrolled over 18000 subjects at more than 1000 centers in 40 countries. The subjects received either twice per day apixaban or “dose-adjusted” warfarin. I’m assuming that means a dose of warfarin necessary to achieve an international normalized ratio (INR) of no less than 2.0.
Bristol-Meyers Squibb is working with Pfizer and the companies hope to have FDA approval by the end of this year. The drug is already approved in Europe, but for the prevention of deep vein thrombosis in adults after elective hip or knee arthroplasty rather than stroke prevention in atrial fibrillation.
Beyond recognizing that patients taking these new drugs are at risk for bleeding, the implications in rehabilitation are largely unknown. There is no antidote for these medications, and there is no readily available monitoring that will tell health care providers whether or not the drugs are working. If these drugs are taken, they work. But we know that most people don’t take their meds as prescribed, especially over the long term. We’ll have to wait and see on this one, and on rivaroxaban, and on dabigatran. Keep an eye out right here for more info in the future – once I know something, I’ll make sure you know it, too.