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Originally published June 30 2009

FDA Scientists Warn About Bleeding Risk of Bayer's Blood-Thinning Drug

by David Gutierrez, staff writer

(NaturalNews) The FDA has publicly released documents from science reviewers expressing concern over the blood-thinning drug rivaroxaban, marketed by Bayer AG and Johnson & Johnson (J&J) as Xarelto in Canada and Europe. The drug has yet to receive regulatory approval in the United States, but an application is pending.

The pill, introduced as a competitor to Sanofi-Aventis' injectable drug Lovenox (enoxaparin), is indicated for once-a-day short term use in order to prevent blood clots following hip- or knee-replacement surgeries. A series of randomized clinical trials (RECORD) on a total of 6,183 participants found Xarelto to be just effective as Lovenox, if not more so, but also that it was twice as likely to cause bleeding.

"The evidence that administration of rivaroxaban (Xarelto) could lead to bleeding events in significantly more patients relative to enoxaparin amplifies [the] safety concern for rivaroxaban," FDA staff wrote.

Concerns have also been raised over the possibility that Xarelto might increase patients' risk of liver damage. One participant in the RECORD trials died of liver toxicity. FDA staff noted that more long-term studies would be needed to gain understanding of the drug's liver risks.

Two days after the agency released its scientists' concerns, an FDA advisory panel recommended approval of the drug for short-term use, and in Europe and Canada. The panel acknowledged that Xarelto is more likely to cause bleeding than Lovenox.

Approximately 800,000 hip- and knee-replacement surgeries take place in the United States every year, providing only a relatively small market for Xarelto or Lovenox. But analysts expect Bayer and J&J to eventually seek approval for long-term use of the drug for stroke prevention. According to analysts from Morgan Stanley, sales of Xarelto for hip- and knee-replacements will likely peak at $200 million per year, yet Bayer has projected eventual annual sales of $2.6 billion for all uses.

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