GlaxoSmithKline (NYSE: GSK) and its partner XenoPort (Nasdaq: XNPT) has won approval from the U.S. Food and Drug Administration for its restless legs syndrome drug.

A little over a year ago, the FDA rejected the treatment, which is called Horizant, and required more tests.

“Clinical experience has substantiated that restless legs syndrome, also referred to as Ekbom Disease, is a long-term neurological condition characterized by an urge to move caused by unpleasant sensations in the legs,” said Richard Bogan, a South Carolina-based doctor who served as a clinical trial investigator. “Our experience has shown that patients with moderate-to-severe primary Restless Legs Syndrome can suffer from a range of disruptive symptoms and may benefit from a new treatment option.”
GSK and XenoPort announced the FDA’s decision Wednesday night. XenoPort, which is based in California, developed the drug.
In 2010, the FDA raised questions about tumors in rats that occurred as part of clinical trials. GSK and XenoPort filed the new drug application in January 2009.

Analysts at Wall Street analysis firm Jefferies believe the drug could generate $500 million a year in sales.

For the full GSK announcement and additional details about the drug, read here.

GSK maintains its U.S. headquarters in RTP and employs some 5,000 people in the area.

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