UPDATE 1-Covidien, CombinatoRx painkiller Exalgo gets FDA nod

* CombinatoRx to get $40 mln in milestone from Covidien

* CombinatoRx to also get tired royalties on drug sales

* Covidien sees Exalgo launch in H1, 2010

* CombinatoRx shares soar 44 pct before the bell

March 2 (Reuters) - Covidien Plc COV.N and CombinatoRx Inc CRXX.O said U.S. health regulators approved their once-a-day painkiller tablet Exalgo, triggering a $40 million milestone payment to CombinatoRx from Covidien.

CombinatoRx, which gained access to the drug through its merger with privately held Neuromed Pharmaceuticals Inc late last year, is also eligible to get tiered royalties on Exalgo net sales.

Covidien, which is responsible for all marketing activities for Exalgo in the United States and all post-approval U.S. regulatory filings, expects to launch Exalgo in the first half of 2010.

Exalgo has been indicated for treating moderate to severe pain in opioid-tolerant patients requiring continuous, around-the-clock opioid analgesia for an extended period of time.

Covidien will also own the intellectual property for the product, the companies said in separate statements.

Last year, a U.S. panel of medical experts had said the drug was effective but can be easily misused and Covidien said the drug launch would include a comprehensive risk evaluation and mitigation strategy to ensure the benefits of Exalgo outweigh the potential risks.

CombinatoRx shares soared 44 percent to $1.60 in pre-market trade Tuesday. They closed at $1.11 Monday on Nasdaq.

Covidien shares closed at $49.53 Monday on the New York Stock Exchange. (Reporting by Esha Dey in Bangalore; Editing by Gopakumar Warrier)