UPDATE 1-US advisers back plan to monitor Covidien pain drug

* FDA panelists concerned about potential for abuse

* Agency expected to decide on approval by Nov. 22

WASHINGTON, Sept 23 (Reuters) - A U.S. panel of medical experts backed Neuromed Pharmaceuticals Inc and Covidien's (COV.N) plan to limit potential abuse with their powerful, once-a-day painkiller Exalgo, saying the drug was very effective but could easily be misused.

Neuromed, which is expected to finalize its merger with CombinatoRx CRXX.O later this year, is seeking U.S. Food and Drug Administration approval of its opioid drug for patients who no longer get relief with other similar medications.

Neuromed sold the drug's U.S. rights to Covidien in June.

Company officials told the FDA advisory panel that they aimed to curb abuse by educating patients and having them sign an agreement. It also would require doctors and pharmacists to register to dispense the drug, among other efforts.

FDA's panelists largely agreed Exalgo could help patients feel better and was more convenient. But they said the company needed to closely watch how the drug was used.

Panel chairman Dr. Jeffrey Kirsch, head of anesthesiology at Oregon Health and Science University, said the panel felt Exalgo was "highly efficacious" but very prone to crushing and other methods of abuse compared to other opioid painkillers.

"On the spectrum of abuse, I think it's toward the top," he said.

The FDA will weigh the panel's comments before making a decision on approval, expected by Nov. 22. (Reporting by Susan Heavey; Editing by Tim Dobbyn)