Maybe it's not all that surprising that a medication that doubles as a rat poison isn't very popular with patients.
Warfarin, also known as Coumadin, has been used for five decades as a blood thinner for patients deemed to be at high risk of a stroke because they have atrial fibrillation, or an irregular heart rhythm, which can cause blood clots.
Patients must be closely monitored because the effectiveness of the drug varies over time. Warfarin can cause serious side effects, including internal bleeding. (The high risk of bleeding is what makes it an effective rat killer.) It also interacts with certain foods and medications, complicating the lives of those who are prescribed the anticoagulant. Up to half of the patients who need it simply refused to take it.
However, warfarin is about to face competition from new drugs whose makers say they are easier to tolerate and don't require rigorous monitoring. Boehringer Ingelheim Canada Ltd. recently obtained Health Canada's permission to market a new blood-thinner called Pradax. And Bayer Inc. will soon be seeking regulatory approval for its drug, Xarelto.
But the new offerings will be relatively pricey compared with warfarin which costs just pennies a day. The price of Pradax has been set at $3.20 a day.
Even so, Paul Dorian, a cardiologist at St. Michael's Hospital in Toronto, said the new drugs may be worth the added expense if more patients can be convinced to take a medication that prevents a stroke.