It appears that warfarin, sold under the brand name Coumadin, may be a safer and cheaper alternative to Pradaxa. A new study, published last Monday, highlights the increasing effectiveness of warfarin, a drug that has been on the market for decades. When it was initially released, Pradaxa appeared to be superior to warfarin, but recent concerns over its irreversible bleeding risks are starting to change that opinion.
Warfarin and Pradaxa are blood thinners that are approved to prevent the occurrence of blood clots and stroke in patients with atrial fibrillation (AF), but warfarin has been available for much longer. Warfarin was approved by the U.S. Food and Drug Administration (FDA) in 1954, while Pradaxa has been on the U.S. market since October 2010. Originally, it appeared that Pradaxa would make warfarin obsolete, since it doesn’t require continual monitoring and has minimal food and drug interactions. However, recent reports of incurable hemorrhaging in Pradaxa patients are proving to be a serious hindrance.
Although warfarin and Pradaxa treat the same condition, they differ in mechanism. Pradaxa is a part of a newer class of drugs known direct thrombin inhibitors, which interfere at the end of a chain of enzymatic reactions that cause clotting. Therefore, bleeding that occurs in these patients cannot be treated with anything other than dialysis. Warfarin, on the other hand, is a vitamin K antagonist. As such, it reduces vitamin K levels in the blood by interfering with its cycle; hemorrhaging in warfarin patients can be immediately remedied with vitamin K and fresh frozen plasma.
The lack of an antidote for Pradaxa-induced bleeding is a serious concern in the medical community, especially after 256 Pradaxa-related deaths were reported in the European Medicines Agency’s database last November. In response to the growing concerns, the FDA launched a safety review of Pradaxa’s bleeding risks in December.
The scope of the bleeding problem became even more evident in January, when the Institute for Safe Medication Practices (ISMP) revealed that over 500 cases of bleeding associated with Pradaxa were reported during the first quarter of 2011, as opposed to the 176 cases of bleeding linked to warfarin.
Now, a study published in the Archives of Internal Medicine may further dampen Pradaxa’s success. In addition to being much less expensive, findings reveal that warfarin is quite successful at preventing stroke in AF patients. Researchers found that patients taking warfarin exhibited an annual incidence stroke or systemic embolism rate as low as 1.66 percent. The study also found that a range of 1.4 to 3.4 percent of warfarin patients experienced major bleeding events per year. Furthermore, the researchers noted that these statistics have been declining, which suggests that the drug is becoming more effective as time goes on. Based on this study, it would appear that a more established, time-tested medication is preferable to a newer, riskier one.