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In a recent study published in the Journal of Cardiology, researchers concluded that blood monitoring for patients taking rivaroxaban (Xarelto) could identify those who are at risk of excessive bleeding events.

Yet Xarelto manufacturers advertised their product as being superior to warfarin, the leading anticoagulant, precisely because it didn’t require such monitoring.

Study Suggests Xarelto Blood Monitoring

For the study, researchers from Japan gave 136 patients rivaroxaban to treat non-valvular atrial fibrillation—a treatment the FDA approved in November 2011. The patients had a mean age of 75 years. The researchers performed blood tests at the beginning of the study and two weeks after the patients started taking the drug, to monitor blood-clotting activity.

They found that in some patients, the drug caused a prolonged “thinning” effect, making them more likely to experience serious bleeding events. This effect could be observed in blood tests. The researchers concluded that regular blood monitoring could identify patients at risk for bleeding—a fact that could potentially prevent subsequent bleeding events that could land patients in the hospital.

Manufacturers Advertise Xarelto as More Convenient

Xarelto, a newer generation anticoagulant, was launched onto the market in July 2011, when it was approved to reduce the risk of blood clots after knee and hip replacement surgery. Since then, it has been the subject of adverse event reports regarding excess bleeding. In the Institute for Safe Medication Practices October 2012 QuarterWatch report, the drug was found to have been associated with 158 cases of severe blood clots in only the first quarter of 2012.

Data from the first quarter of 2013 showed that adverse event reports for Xarelto (rivaroxaban) had surpassed those for Pradaxa (dabigatran), mirroring an increase in the number of patients taking the drug. Meanwhile, a number of patients have filed lawsuits against manufacturer Janssen Pharmaceuticals and parent company Johnson & Johnson (J&J), claiming they failed to warn about the dangerous side effects.

Advertising for Xarelto emphasized that it did not require blood monitoring, and thus was a much more convenient option compared to warfarin. As noted in an FDA warning letter to the manufacturers, their materials even stated it explicitly: “Xarelto is the first and only once-a-day prescription blood thinner for patients with AFib not caused by a heart valve problem, that is proven to reduce the risk of stroke—without routine blood monitoring.”

Yet this study suggests that many of the injuries associated with Xarelto may have been prevented had the manufacturers recommended regular blood monitoring, such as that which occurs in patients taking warfarin. The FDA notes in its warning letter that the statement is misleading, for one, because patients with kidney problems may need to be evaluated and the dosage adjusted.

“This overall presentation misleadingly minimizes the risks associated with Xarelto,” the FDA stated, “because it fails to convey this important risk information with a prominence and readability reasonably comparable to the efficacy claims.”

J&J May Have Committed a Grave Error

The conclusions by the researchers of this study may be important evidence in Xarelto lawsuits, as it shows that the manufacturers may have failed to provide not only adequate warnings about their product, but that they may have failed to provide patients and doctors with the proper prescribing information in the first place. If the drug required blood monitoring—even for patients not at risk of renal impairment—that should have been suggested in the beginning, when the drug was first launched.

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