One-Size-Fits-All Xarelto Dose Unwise for Many Patients

When manufacturers first released Xarelto on the market in 2011, they advertised it as a more convenient alternative to the leading blood-thinner, warfarin. Approved for reducing the risk of blood clots following knee or hip replacement surgery, as well as to reduce risk of stroke in patients with non-valvular atrial fibrillation, it came in a single dose that did not require blood monitoring.

Patients on warfarin had to continue to test and monitor their blood to be sure the dose they were using was working correctly. In other words, doctors wanted to be sure that the dose they were prescribing was working sufficiently to reduce clotting risk, but wasn’t causing the blood to thin too much, which could cause dangerous bleeding effects. Results of the blood tests were analyzed and the dose of the drug adjusted, as necessary.

Patients taking Xarelto were told they didn’t have to go through this type of monitoring.

Recent research, however, has suggested that monitoring could have helped prevent dangerous bleeding in patients, particularly those with kidney malfunction. A new editorial in the Journal of the American Medical Association (JAMA) also questions the wisdom of a one-size-fits-all dose of Xarelto and other similar blood thinners.

Xarelto Patients Would Benefit from Blood Monitoring

In March 2015, researchers published a study in the Journal of Cardiology that concluded blood monitoring could identify patients at risk of serious bleeding side effects. Researchers examined 136 patients with non-valvular atrial fibrillation who were taking Xarelto (rivaroxaban), and found that in 29 of them, the “peak prothrombin time”—which is an indication of how much the drug is “thinning” the blood or reducing the clotting time—was significantly longer than baseline.

That means that these patients would have been at risk for excessive bleeding. Such testing, the researchers stated, could have helped determine which patients were vulnerable to serious side effects.

The Institute for Safe Medicine Practices reported that by the first quarter of 2013, the number of adverse bleeding events associated with Xarelto had overtaken those with Pradaxa (dabigatran—a similar blood thinner), with nearly 700 cases reported.

Any excessive bleeding with these drugs is much more serious than that linked with warfarin. Doctors can treat excessive warfarin bleeding with injections of vitamin K, but there is no similar antidote to Xarelto or Pradaxa bleeding, making these events much more serious and potentially deadly.

Xarelto Manufacturers Need to Come Up with New Dosing Recommendations

In March 2015, J. Robert Powell, PharmD, published an editorial in JAMA questioning the dosage recommendations for Xarelto and other similar newer anticoagulants.

“The ability to understand how to optimally achieve anticoagulation with warfarin took 60 years since its approval by the U.S. Food and Drug Administration (FDA) in 1954,” he writes. “How long will it take clinicians to understand how to optimally dose the new thrombin and factor Xa inhibitors in all patients?”

He goes on to state that while the newer drugs come in one dose, supposedly without need for monitoring, such “convenience” may sacrifice patient safety, and may have a lot more to do with marketing and sales then what’s actually best for patients. Even in the initial clinical studies used to demonstrate the drugs’ capabilities, patients experienced varying levels of effectiveness with the drug.

Powell concludes that manufacturers should conduct additional clinical trials to come up with new dosing recommendations that would better protect patients from dangerous bleeding side effects.