January 12, 2015 — Portola Pharmaceuticals may have just discovered an antidote for Xarelto, a blood-thinning medication linked to uncontrollable and sometimes fatal bleeding.
Reuters reported that the intravenous medication, andexanet alfa, met its primary endpoint of “immediately and significantly” reversing Xarelto.
Phase III results of the ANNEXA-R study were based on 41 healthy volunteers aged 50-75 years old. Additional data is expected later this year. In October, the drug was also shown to be effective at reversing Eliquis, a similar blood-thinning medication.
The FDA gave andexanet alfa breakthrough therapy status in 2013, which can help speed up the development and approval of new drugs for life-threatening conditions.
Xarelto belongs to a new generation of blood-thinning medications that work by inhibiting factor Xa, a blood clotting enzyme. When it hit the market, it had no reversal agent to counteract its blood-thinning effects — unlike warfarin, which can be reversed with a simple dose of Vitamin K.
The problem is that about 1-4% of people on Xarelto experience major bleeding, and an additional 1% require emergency surgery. A doctor must de-activate any blood-thinners so a patient’s blood can form life-saving blood clots. Unfortunately, not even dialysis can remove Xarelto from the blood because it binds too tightly to blood plasma.
The manufacturer of Xarelto, Bayer and Janssen Pharmaceuticals, are now facing about 80 lawsuits in a federal Multi-District Litigation (MDL) in Louisiana. The litigation has quadrupled in size since it was created last month, with all plaintiffs accusing drug-makers of downplaying Xarelto’s bleeding risks.