Coumadin gives lesson for new blood thinners
Among blog posts and user forums appearing from May 1999 to September 2010, the authors found 1,223 mentions of either the brand name Coumadin or generic name warfarin, making it the most talked about anticoagulant by patients and physicians. That's not surprising considering that the 60-year-old drug is the most commonly used oral blood thinner in the US.
While warfarin may be the standard of care, determining whether to put patients on it is anything but.
“You would think, theoretically, that after  years, people would understand anticoagulation therapy,” said Michele Bennett, COO of Wool Labs, which issued the report, a follow-up to its analysis showing how social media gave an early warning on Avandia safety issues. “There's still a lot of disagreement between patients and physicians about how to treat and when, and whether to keep patients on it for life.”
A 2009 conversation on Medscape involving a 45-year-old male, who comes to the ER suspecting a deep vein thrombosis or pulmonary embolism, goes on for 45 posts, featuring differing views from hematologists, PCPs and an emergency room physician on what tests to order to determine whether to anticoagulate.
“This just shows me that there is dramatic confusion and disagreement about this issue,” wrote one poster, a family doctor trying to decide whether to allow his daughter to go on long-term warfarin therapy.
Management issues don't help. The drug requires frequent blood tests and dosage adjustments to prevent excessive bleeding, and this can become cumbersome for doctor and patient alike. These issues have prompted many patients to question the wisdom of lifelong treatment, and sentiment is low.
The angst surrounding warfarin is the main reason pharmaceutical companies have been working to come up with a replacement that doesn't require coagulation testing. Now there is one: Boehringer Ingelheim's Pradaxa. An NDA for J&J/Bayer's Xarelto has been filed with FDA.
Neither new drug requires blood monitoring. So, will it be smooth sailing for these new entrants? Not likely, as each has had side effects. In a Pradaxa phase III study, a very small but statistically significant increase in the risk of heart attack was seen. For Xarelto, potential liver issues surfaced during late-stage testing.
Because physicians may have to worry about these other safety issues, the lack of blood monitoring is no guarantee of acceptance among HCPs. “We're not seeing evidence in social media that there will be really fast uptake,” said Bennett. “I see comments from physicians saying, ‘I'll wait and see.'” The potential side effects may defuse the testing issue. “The nice thing about Coumadin is there is no need to monitor other parts of the body when you take it.”
Patients have largely ignored warfarin's adverse interactions to other drugs, including Plavix. A bigger concern is warfarin's food interactions, and this may be where the rubber meets the road for Pradaxa and Xarelto.
The newcomers will no doubt face skeptical managed care organizations reluctant to put a more expensive drug on formulary alongside relatively cheap warfarin therapy. “[Manufacturers] definitely need to talk about how to differentiate themselves from Coumadin in a way that says the cost and effort to figure it out is worth it,” Bennett advised. —Marc Iskowitz