The Food and Drug Administration (FDA) released an updated safety review November 2nd on Pradaxa (dabigitran) the novel anticoagulant used to prevent stroke in those with atrial fibrillation. Their release states that Pradaxa does not cause any higher incidence of bleeding than that seen from Coumdain (warfarin), the oldest oral anticoagulant on the market. That’s good to know, assuming it’s true. More specifically, FDA stated in their release “that bleeding rates associated with new use of Pradaxa do not appear to be higher than bleeding rates associated with new use of warfarin”. Key words: “appear” and “new”. When I hear the word “appear” I interpret it to mean, “Our review of limited data don’t really give us a whole lot of confidence in our conclusion.” (Their data were limited to insurance claims and the FDA Mini-Sentinel pilot database.) And when I think of “new” use for either anticoagulant I think that either drug would have the same rate of bleeding when just started due to difficulty finding that optimum dose, unscreened or unknown drug interactions, not accounting for poor kidney function, and other factors. But what about long term or chronic use? Warfarin has routine lab monitoring to detect changes in bleeding risk whereas Pradaxa has none.
In another review of safety data, ISMP released their analysis of FDA data from 3rd and 4th quarters of 2011 in which reports of bleeding from Pradaxa far exceeded those from warfarin, although the authors do caution about reading into those data since there could be more bleeding events reported for Pradaxa due to its new status and popularity. Here’s the ISMP link: http://www.ismp.org/quarterwatch/pdfs/2011Q4.pdf Another perspective from an ER physician, in an article in the NY Times, is the apparent helpless feeling he would have when people came in with hemorrhage from Pradaxa, because there is no antidote and everything tried did not save a life, whereas warfarin has vitamin K as a way to treat it’s toxic effects. And there’s a posted comment on Elder Drugs from a daughter who states her mother died recently due to hemorrhage, in that case suggesting that the MD did not pay attention to signs of internal bleeding and may not have adjusted the dose based on low kidney function. Studies have shown that prescribers would benefit, along with their patients, if they paid closer attention to patient-reported symptoms of adverse drug events and actually did something about them.
When Pradaxa came out I failed to endorse the drug, and still maintain that position. I also recall a retired physician’s perspective on the matter citing his knowledge of the old-old adult and their susceptibility to adverse effects form medications. He predicted that older adults would most likely experience significant harm from this drug. So far his prediction is on course, unfortunately.