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Use of Anti-Clotting Drug Should Not Be Expanded to Prevent Strokes, Public Citizen Tells FDA

Oct. 20, 2011 

Use of Anti-Clotting Drug Should Not Be Expanded to Prevent Strokes, Public Citizen Tells FDA

Drug Proposed as Long-Term Therapy for Stroke Prevention Has Questionable Safety and Effectiveness, Clinical Trial Raises Ethical Concerns

WASHINGTON, D.C. – A drug that is used and approved to prevent blood clots following orthopedic surgery should not be additionally approved to prevent strokes and systemic embolism in patients with a common heart rhythm disorder because its safety and effectiveness are uncertain, and two proven drugs already exist to treat this condition, Public Citizen said in a letter sent today to the Food and Drug Administration (FDA).

The drug, rivaroxaban, also known as Xarelto, may cause a rebound occurrence of strokes when the medication is discontinued, and the uncertainty surrounding the clinical trial testing the drug prompted three FDA reviewers to explicitly recommend against approving the drug for this additional use.

Problems with this trial centered on the inadequate use of warfarin, the standard treatment to prevent such strokes, in the control population, thereby falsely making rivaroxaban appear superior. Other concerns included the company’s unjustified decision to test a single, once-daily dose of rivaroxaban, despite evidence from previous studies that a twice-daily regimen was safer. In addition, the failure to provide adequate warfarin therapy during and after the trial exposed patients to life-threatening risks, raising ethical concerns about the conduct of the trial, Public Citizen said.

“With so much uncertainty as to whether rivaroxaban is truly as safe and effective as existing therapy to prevent such strokes, and with two drugs already available to treat this condition, the FDA must not rush to approve rivaroxaban for such a broad use,” said Dr. Sammy Almashat, a researcher with Public Citizen’s Health Research Group and co-author of the letter.

The FDA approved rivaroxaban in July 2011 for short-term use in the prevention of blood clots in patients who undergo surgery of the hip or knee. Now, the company is asking the FDA to approve the drug to treat a different condition: strokes in patients with a relatively common heart disorder called atrial fibrillation. This new proposed use would expand the drug’s market enormously, exposing potentially millions of patients to a medication that has yet to be proven as safe and effective as warfarin, a decades-old drug and the main-stay treatment for this condition.

An FDA advisory committee on Sept. 8 recommended that rivaroxaban be approved for the additional use despite FDA reviewers’ explicit recommendations that it not be because of the flawed clinical trial. Even some advisory committee members voting in favor of approval implicitly acknowledged that rivaroxaban is not as safe and effective as existing therapies. They recommended that the drug be restricted for use as a third-line treatment to be used only when the other two proven therapies fail.

The FDA should follow the recommendations of its expert reviewers and reject the new request to approve rivaroxaban to prevent strokes until the drug’s manufacturers conduct another, better-performed clinical trial, Public Citizen said. Public Citizen also called on the agency to investigate the design and conduct of the clinical trial and the manufacturer’s failure to provide certain patients with the appropriate standard of care.

Public Citizen is a national, nonprofit consumer advocacy organization based in Washington, D.C. For more information, please visit www.citizen.org