Ever since the drug warfarin was discovered to be a highly effective anti-clotting agent as well as a good rat poison in the early 1950s, it has been the frontline weapon in preventing stroke among those with atrial fibrillation. But its growing use has always raised the specter of dangerously hard-to-stanch bleeding if someone taking it is wounded or bleeds internally from a fall or a car accident.
Roughly six decades after its introduction, Kcentra has been approved by the Food and Drug Administration. It's a new product designed to quickly reverse the effects of warfarin. The prothrombin complex concentrate is made from the pooled plasma of healthy donors, and it joins a cluster of other "reversal agents" capable of restoring coagulation, including vitamin K and fresh-frozen plasma, in people who take warfarin.
But vitamin K takes time to work, and so does frozen plasma, which must be thawed and typed to the recipient's blood group. Kcentra does not need to be typed to the recipient's blood and so can be used more quickly to reverse the effects of warfarin.
The new agent does not, however, work to reverse the effects of two anticoagulants that are new to the market -- dabigatran (marketed as Pradaxa) or rivaroxaban (marketed as Xarelto). Last year, a case study in the Journal of Neurosurgery underscored that physicians still lack reversal agents that can restore coagulation in patients taking these new medications, with sometimes deadly results.
Just over 2 million Americans are thought to have atrial fibrillation, which puts them at much higher risk of stroke, and that number is expected to grow to 5.6 million by 2050 as the population ages. Many taking warfarin are switching to the newer and more effective stroke-preventing medications, and most newly diagnosed atrial fibrillation patients appear to be prescribed them first.
As a result, the Food and Drug Administration is eager to consider therapies that can reverse the anticoagulant effects of these new drugs, as well as products such as Kcentra, which can speed coagulation in those taking warfarin.Copyright © 2014, Los Angeles Times