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Problematic Findings in New Xarelto Study

Staff Writer

Last updated: November 22, 2016 3:32 pm

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Recently, a study of Xarelto (Rivaroxaban) — an anticoagulant medication developed and manufactured by Bayer and marketed by Janssen Pharmaceutica in the U.S. — was conducted on more than 1,500 people in 16 countries. The study, known as X-VeRT, purported to determine the effects of Xarelto against vitamin K antagonist therapy (another anticoagulant treatment) on patients who underwent cardioversion, a procedure that helps the heart to adopt a consistent rhythm. Such anticoagulant treatments are recommended by the American Heart Association (AHA) for several weeks before and after cardioversion.

Possible Xarelto Study Bias & Size Concern

However, reports indicate that there may be some issues with how the study was conducted. Specifically, X-VeRT was conducted as a randomized, open-label study. The highest trial standard is the double-blind study, which prevents patients and doctors from knowing which treatment is being administered, which can often help minimize intentional or unintended bias on multiple fronts. With an open-label study, both doctors and patients are aware of which drug was being used for treatment, thus potentially skewing the results. The authors acknowledged that potential, noting that the open-label nature of the study “could have introduced a bias in the reporting and/or adjudication of outcome events.” 1

Furthermore, even if the results of the study are accurate, they may not be applicable to the population at large. With only about 1,500 participants, the study size is too small to be statistically significant, and the authors explain that “between 25,000 and 30,000 patients would be required” to show whether Xarelto is as effective as vitamin K antagonist therapy in helping to prevent cardiac arrest before and after cardioversion. The authors go on to state, that “X-VeRT was underpowered to provide statistically rigorous results and was thus exploratory in nature.” Even though the results might point to a generally favorable medical outcome, upon presenting the findings at the European Society of Cardiology, the lead author Ricardo Cappato cautioned that “these data are preliminary.” 2

Although Bayer, Janssen Pharmaceutical and others are praising the results of the study, there is still some concern about the drug in other areas. Xarelto is currently the subject of various lawsuits related to severe side effects, such as hemorrhaging.

13,500 Xarelto Bottles Recalled

Around the same time these study results were published, Johnson & Johnson’s Janssen unit issued a voluntary, nationwide recall of 13,500 bottles of Xarelto (rivaroxaban), a blood thinner developed in part by Bayer that’s administered for preventing blood clots and strokes. According to an FDA Enforcement Report recall notice, samples of the drug originating from a plant in Puerto Rico were inspected and found to contain microbial contamination following a consumer complaint.

Janssen had a similar incident in 2013 when 5,000 virals of the antipsychotic drug Risperdal Consta were recalled for mold contamination.

Johnson & Johnson released Xarelto to the U.S. market three years ago with initial success. However, there have been several recent lawsuits filed by patients experiencing life-threatening, uncontrollable bleeding as a side effect of the drug. There is currently no antidote to stop this fatal bleeding.

In response to the recall, Janssen issued the following statement: “[We are] committed to ensuring the quality of [our] products. We received a complaint involving one bottle of a XARELTO sample, and therefore are recalling the entire lot. All XARELTO dosage strengths remain available for patients and product obtained at a pharmacy is not impacted.”

  1. Cappato, Ricardo, et al. “Rivaroxaban vs. vitamin K antagonists for cardioversion in atrial fibrillation.” European Heart Journal Advance Access. (Sept. 2, 2014) Accessed Oct. 17, 2014. 

  2. European Society of Cardiology. “X-VErT – Pre-treatment with rivaroxaban may expedite cardioversion.” (Sep. 2, 2014) escardio.org. Accessed Oct. 17, 2014.