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FDA Panel Rejects Xyrem as Fibromyalgia Treatment

FDA Panel Rejects Xyrem as Fibromyalgia Treatment Advisory Panel Members Worry About Potential for Abuse of Drug That's Similar to GHB WebMD Medical News By Matt McMillen Reviewed by Laura...

Aug. 20, 2010 -- An FDA advisory panel today overwhelmingly rejected the application of Jazz Pharmaceuticals for the approval sodium oxybate (Xyrem) for the treatment of fibromyalgia.

The drug is chemically similar to GHB, widely considered a date-rape drug. Approving it for such a large patient population -- 5 million people are estimated to suffer from fibromyalgia -- would risk flooding the streets with a pharmaceutical-grade version of the highly controlled substance.

"Sodium oxybate and GHB are the same thing," said panelist Lewis Nelson, MD, of the New York University School of Medicine. "This is much better than the stuff you get on the street, and that is the problem."

Currently, the drug is only approved for the treatment of narcolepsy. It has been prescribed for 35,000 people since it was introduced in 2002.

"When drugs like GHB get out there, we wish it hadn't happened," said Thomas Kosten, MD, a Baylor University professor of psychiatry and addiction.

Risks vs. Benefits

Kosten, who vociferously opposed approval, also cited a lack of convincing evidence by the drugmaker that the risks involved in releasing the drug to such a large population were balanced by its effectiveness in treating fibromyalgia-related pain and sleeping problems, the two conditions for which Jazz was seeking approvals.

"Without any data to show that this is better than existing medications, I think we are foolish to consider approving this drug," Kosten said in the discussion immediately preceding the vote.

The panel's vote contrasted with the FDA's view of the data provided by Jazz, which included two studies measuring pain relief, and another study that tested its effectiveness as a sleep aid.

"The agency agrees that there is evidence of efficacy" for treating pain, said FDA statistician David Petullo, MS, who reviewed the studies. The FDA did not, however, accept Jazz's claims that sodium oxybate had a positive effect on sleep.

In the public comment period, the majority of the speakers supported approval of the drug. Many of them had participated in the Jazz-run studies. They explained, often emotionally, how much they had benefited from sodium oxybate after failing to respond to any of the three drugs approved to treat fibromyalgia.

As many as 50% of those with the disease do not respond to available medications, said Jon Russell, MD, director of the University Clinical Research Center at the University of Texas Health Science Center at San Antonio, who spoke on behalf of Jazz.

"We need more options for the care of fibromyalgia patients," said Russell, "and those should have different mechanisms of action."

Concerns About Drug Abuse

The panelists were not convinced that the company had made enough of an effort to prove sodium oxybate's effectiveness, nor did they have confidence in the company's ability to monitor and manage the potential risks associated with the drug.

The panel cited a lack of data concerning drug interactions for patients on multiple medications, as well as risks for patients with multiple conditions; the likelihood of misuse; and doctor and patient confusion over what one FDA official referred to as the drug's "unusual and complex dosing arrangement."

But it was the link to GHB and the potential for abuse in a vastly expanded, difficult-to-monitor market that drove the 20-2 vote. 

Sidney Wolfe, MD, director of Public Citizen's Health Research Group, summed up the panel's position: if a drug needs to get on the market, there needs to be a mechanism in place to mitigate risk, which the panel clearly found lacking.

"The other option," he said, "is to not approve it."

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