US regulators have approved XenoPort Inc's drug Horizant to treat restless legs syndrome (RLS).
Horizant, developed with partner GlaxoSmithKline Plc, is a long-lasting version of gabapentin.
In February 2010, the US Food and Drug Administration declined to approve Horizant, raising concerns about a pancreatic cancer signal seen in rats at very high doses.
The FDA has asked the company to conduct a number of post-marketing studies, focusing mainly on the potential for driving impairment.
Up to 10% of the US population may have RLS, according to the National Institute of Neurological Disorders and Stroke (NINDS).
Some industry analysts believe Horizant will face stiff competition from the products currently being used to treat RLS generic agents Requip and Mirapex, and off-label gabapentin usage.
XenoPort is also developing Horizant for post-herpetic neuralgia and some see a limited market there as well given that gabapentin itself is approved as a cure.
(Reuters Health,Shravya Jain, April 2011)
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