UPDATE 2-Glaxo, Xenoport's drug gets FDA nod for new use

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June 7 (Reuters) - Drugmaker XenoPort Inc and its partner GlaxoSmithKline Plc said the U.S. health regulator approved their drug to treat shingles related nerve pain that may cause disability in some people.

XenoPort will get a milestone payment of $10 million from Glaxo following first sales of the drug, Horizant, to treat post-herpetic neuralgia (PHN) in adults.

Post-herpetic neuralgia follows the healing of an outbreak of herpes zoster, commonly known as shingles.

Around a million people in the United States develop shingles each year and about 10 percent of those develop PHN.

Horizant, co-developed by XenoPort and Glaxo, is already approved to treat restless legs syndrome (RLS) in the United States, but is not recommended for RLS patients who sleep during the day and remain awake at night.

In a 12-week, controlled study on patients with PHN, drowsiness and dizziness were the most frequently reported side effects.

Shares in Xenoport, which has a market capitalization of about $217 million, were up 7 percent premarket on Thursday. They closed at $6.07 on Wednesday on the Nasdaq. (Reporting by Ben Hirschler in London and Balaji Sridharan in Bangalore; Editing by Kate Kelland, Roshni Menon)